the unionidae are a family of freshwater mussels , the largest in the order unionoida , the bivalve mollusks sometimes known as river mussels , or simply as unionids .

the range of distribution for this family is world-wide .

it is at its most diverse in north america , with about 297 recognised taxa , but china and southeast asia also support very diverse faunas .

freshwater mussels occupy a wide range of habitats , but most often occupy lotic waters , i.e. flowing water such as rivers , streams and creeks .

unionidae

water quality guidance for protection of freshwater mussels ( unionidae ) from ammonia exposure .
matteson , m . 1955 . studies on the natural history of the unionidae .
water quality guidance for protection of freshwater mussels ( unionidae ) from ammonia exposure . - pubmed - ncbi
phylogenetic analysis of prisodontopsis tomlin , 1928 and mweruella haas , 1936 ( bivalvia : unionidae ) . . .
early life - history and conservation status of venustaconcha ellipsiformis ( bivalvia , unionidae ) in minnesota
by daniel c . allen
allen , w . 1921 . studies of the biology of freshwater mussels : experimental studies of the food relations of certain unionidae .
what made you want to look up unionidae ? please tell us where you read or heard it ( including the quote , if possible ) .
kohl , m . 2000 .
unionidae
( on - line ) . freshwater molluscan shells . accessed august 31 , 2003 at urltoken .
to cite this page : winhold , l . 2004 .
unionidae
( on - line ) , animal diversity web . accessed july 09 , 2018 at urltoken
strayer , d . 1983 . the effects of surface geology and stream size on freshwater mussel ( bivalvia : unionidae ) distribution in southeastern michigan , u . s . a . .
in previous molecular phylogenetic analyses of the freshwater mussel family unionidae ( bivalvia : unionoida ) , the afrotropical genus coelatura had been recovered in various positions , generally indicating a paraphyletic unionidae . however that result was typically poorly supported and in conflict with morphology - based analyses . we set out to test the phylogenetic position of coelatura by . . . [ show full abstract ]
zebra mussel infestation of unionid bivalves ( unionidae ) in north america . dw schlosser , tf nalepa , and gl mackie . amer . zool . , 36 : 300 - 310 ( 1996 )
…and two important families , the unionidae and corbiculidae , are predominantly freshwater with complicated reproductive cycles . there are no terrestrial bivalves , although some high - intertidal and freshwater species can withstand drought conditions .
graf , d . 2002 . molecular phylogenetic analysis of two problematic freshwater mussel genera ( unio and gonoidea ) and a re - evaluation of the classification of nearctic unionidae ( bivalvia : palaeoheterodonta : unionoida ) .
daniel c . allen , bernard e . sietman , daniel e . kelner , mark c . hove , et al . .
early life - history and conservation status of venustaconcha ellipsiformis ( bivalvia , unionidae ) in minnesota
this key covers the 3 subfamilies of unionidae that we have collected in north dakota rivers and streams . this key will aid you by providing simple features you can look for to identify your specimen . after using the key , confirm the identity of you specimen by reading the genera page .
in the freshwater unionidae the released larva , called a glochidium , often has sharp spines projecting inward from each valve . the larva attaches to either the gills or fins of passing fish and becomes a temporary parasite . eventually , it leaves the fish , falls to the lake floor , and metamorphoses…
…of the bivalve mollusk families unionidae and margaritiferidae . of these , 21 have become extinct in the past century , and another 120 species are in danger of extinction . during this same period , engineers have extensively dammed and channeled north america’s rivers . the tennessee river , for example , is dammed along its entire…
the unionidae , of worldwide distribution , are most diverse in eastern and central north america , and secondarily in china and southeast asia . these include north america ' s most abundant , interesting , and economically valuable shells . because of their long association with activities of leisure , livelihood and trade , many have acquired colorful common names .
a refuge for native freshwater mussels ( bivalvia : unionidae ) from impacts of the exotic zebra mussel ( dreissena polymorpha ) in lake st . clair . dt zanatta , gl mackie , jl metcalfe - smith , and da woolnough . j . great lakes res . 28 ( 3 ) : 479 - 489 internat . assoc . great lakes res . , 2002
zhou et al . ( 2007 , acta zoologica sinica , 53 : 1024–1030 ) reported the eastern asian freshwater mussel genus lamproula sensu lato simpson , 1900 ( unionidae ) to be polyphyletic and advocated a revision of the genus - and family - level classifications . however , their taxon sampling and analyses were insufficient to infer accurately the systematic placement of the resultant clades . we . . . [ show full abstract ]
ty - jour ti - life history of the endangered fine rayed pigtoe fusconaia cuneolus ( bivalvia , unionidae ) in the clinch river , virginia t2 - american malacological bulletin . vl - 10 ur - urltoken pb - [ american malacological union ] , cy - [ hattiesburg , miss . ? ] : py - 1993 sp - 83 ep - 91 sn - 0740 - 2783 au - bruenderman , s a au - neves , r j er -
. . . although the statistical biogeographic models assume that the crown group of the family was widely distributed across the east laurasia ( east asia + mediterranean ) , the fossil evidence shows an east asian origin for both the stem and the crown group ( e . g . , chen , 1984 ; jingshan et al . , 1993 ; ma , 1994ma , , 1996jiang et al . , 2005 ; pan and sha , 2009 ; fang et al . , 2009 ; yao et al . , 2011 china ( fang et al . , 2009 ) is here proposed as a fossil member of the crown group of margaritiferidae + unionidae , most likely re - presenting a separate ancestral family ( supplementary tables 3 and 4 ) . this agrees with graf et al . ( 2015 ) and skawina and dzik ( 2011 ) , who suggested that pre - jurassic freshwater bivalves may represent the stem - groups of modern unionoid clades . bolotov et al . ( 2017a ) showed that the unionidae most likely originated in east and southeast asia , which is consistent with the hypothesis of an asian origin for both families . . . .
@ article { bhlpart143222 , title = { life history of the endangered fine rayed pigtoe fusconaia cuneolus ( bivalvia , unionidae ) in the clinch river , virginia } , journal = { american malacological bulletin . } , volume = { 10 } , copyright = { in copyright . digitized with the permission of the rights holder } , url = urltoken publisher = { [ hattiesburg , miss . ? ] : [ american malacological union ] , 1983 - } , author = { bruenderman , s a and neves , r j } , year = { 1993 } , pages = { 83 - - 91 } , }
the shell morphology and population dynamics of the five british unionidae are compared within a sympatric population . pseudanodonta complanata is distinguished from anodonta anatina and a . cygnea by the hinge length–shell length relationship ; this morphological distinction may serve as a useful tool in the identification of this threatened species . the shell length at a given annulus was remarkably similar for all five species , although the asymptotic length is reached most quickly in p . complanata and unio pictorum . p . complanata is relatively short - lived and attains the lowest maximum length , while a . cygnea lives more than twice as long and attains almost double the length of p . complanata . unio spp . have a short gravid season over the summer , while anodonta spp . have a long gravid period , lasting from autumn through to spring . unlike other members of the anodontinae , p . complanata has a short breeding season , overlapping with that of the unio spp .
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» genus amphinaias crosse & p . fischer , 1894 accepted as cyclonaias pilsbry in ortmann & walker , 1922
» genus amygdalonaias crosse & p . fischer , 1894 accepted as truncilla rafinesque , 1819
» genus amygdalonajas crosse & p . fischer , 1894 accepted as truncilla rafinesque , 1819
» genus cokeria w . b . marshall , 1916 accepted as amblema rafinesque , 1820
» genus corunculina simpson in f . c . baker , 1898 accepted as toxolasma rafinesque , 1831
» genus lapidosus simpson , 1900 accepted as disconaias crosse & p . fischer , 1894
» genus mesonaias crosse & p . fischer , 1894 accepted as cyrtonaias crosse & p . fischer , 1894
» genus anadontoides simpson in f . c . baker , 1898 accepted as anodontoides simpson in f . c . baker , 1898
» genus anodontopsis simpson in f . c . baker , 1898 accepted as anodontoides simpson in f . c . baker , 1898
» genus brachyanodon crosse & p . fischer , 1894 accepted as anodonta lamarck , 1799
» genus flexiplis rafinesque , 1831 accepted as pyganodon crosse & p . fischer , 1894
» genus flexiptis rafinesque , 1831 accepted as pyganodon crosse & p . fischer , 1894
» genus mesanodon crosse & p . fischer , 1894 accepted as anodonta lamarck , 1799
» genus nayadina de gregorio , 1914 accepted as utterbackia f . c . baker , 1927
» genus utterbachia f . c . baker , 1927 accepted as utterbackia f . c . baker , 1927 ( original misspelling )
genus nodularidia cockerell , 1901 accepted as nodularia conrad , 1853 ( unnecessary nom . nov . pro nodularia conrad , 1853 )
bieler r . , carter j . g . & coan e . v . ( 2010 ) . classification of bivalve families . pp . 113 - 133 , in : bouchet p . & rocroi j . - p . ( 2010 ) , nomenclator of bivalve families . malacologia 52 ( 2 ) : 1 - 184 . [ details ]
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graf , d . l . & k . s . cummings . 2013 . the freshwater mussels ( unionoida ) of the world ( and other less consequential bivalves ) , updated 8 august 2013 . mussel project web site , urltoken
turgeon , d . d . , j . f . quinn , jr . , a . e . bogan , e . v . coan , f . g . hochberg , w . g . lyons , et al .
common and scientific names of aquatic invertebrates from the united states and canada : mollusks , 2nd ed .
disclaimer : itis taxonomy is based on the latest scientific consensus available , and is provided as a general reference source for interested parties . however , it is not a legal authority for statutory or regulatory purposes . while every effort has been made to provide the most reliable and up - to - date information available , ultimate legal requirements with respect to species are contained in provisions of treaties to which the united states is a party , wildlife statutes , regulations , and any applicable notices that have been published in the federal register . for further information on u . s . legal requirements with respect to protected taxa , please contact the u . s . fish and wildlife service .
lampsilis cardium rafinesque , 1820 , in a very shallow creek in southwest missouri . the gray mantle flaps have black and white
eyespots
and undulate back and forth rhythmically . click here for animated sketch .
the anodontinae ( subfamily status for anodontini used by banarescu in his worldwide synthesis ) and the genus anodonta have wide distribution in the northern hemisphere . 11 genera have been listed for east and southeast asia , and two in western asia .
twenty north american genera further grouped into five subtribes by burch . names in parenthesis are older synonyms in common use ;
acuticostinae : east and southeast asia , eight genera . lamellidentina : one genus in india and afghanistan . psilunioninae : one genus in southern europe , northern africa . unioninae s . s . ( not equivalent to the north american unioninae , above ) six genera in europe , east asia and africa , including unio itself .
this is a directory page . britannica does not currently have an article on this topic .
dog , ( canis lupus familiaris ) , domestic mammal of the family canidae ( order carnivora ) . it is a subspecies…
more than 40 species of freshwater mussels are native to the great lakes . all are filter feeders . most are considered endangered and / or restricted to protected areas . exotic dreissenid mussels are largely to blame - - faster - growing dreissenids settle on the shells of the native species effectively smothering them . adults are male and female , fertilization usually takes place internal to the female with young brooded in the mother ' s gills until they reach a glochidia stage . the juvenile glochidia stages of unionids are usually parasitic on fish - often confined to a single host species .
* * reported locations based on a limited literature search . codes indicate presence reported but absence of a code should not be interpreted as a species absence .
abundance , biomass , and species composition of benthic macroinvertebrate populations in saginaw bay , lake huron , 1987 - 96 . thomas nalepa , david fanslow , margaret lansing , gregory lang , mark ford , gerald gostenik , and david hartson . noaa technical memorandum glerl - 122 .
relationships among zoobenthos , sediments , and organic matter in littoral zones of western lake erie and saginaw bay . 1983 . richard a . cole and diana l . weigmann . jglr 9 ( 4 ) 568 - 581 .
wave - zone macrobenthos of the exposed canadian shores of the st . lawrence great lakes . 1978 . d . r . barton and b . n . hynes . jglr 4 ( 1 ) 27 - 45 .
benthic community structure and composition among rocky habitats in the great lakes and keuka lake , ny . 1987 . michael h . winnell and david j . jude . jglr 13 ( 1 ) 3 - 17 .
changes in the biodiversity of freshwater mussels in the canadian waters of the lower great lakes drainage basin over the past 140 years jl metcalfe - smith , sk staton , gl mackie , and nm lane . j . great lakes res . 24 ( 4 ) : 845 - 858 , 1998 .
changes to the deepwater benthos of eastern lake erie since the invasion of dreissena 1979 - 1993 . 1997 . r dermott and d kerec . cjfas 54 : 922 - 930 .
w ( wave zone = 0 - 2m ) based on : wave - zone macrobenthos of the exposed canadian shores of the st . lawrence great lakes . 1978 . d . r . barton and b . n . hynes . jglr 4 ( 1 ) 27 - 45 .
r ( rocky habitats ) based on : benthic community structure and composition among rocky habitats in the great lakes and keuka lake , ny . 1987 . michael h . winnell and david j . jude . jglr 13 ( 1 ) 3 - 17 .
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fm ( u ) otw ( aolcb ) is the web version of the mussel project database . follow the links to browse the data or use the search fields . either way , you win !
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published 2015 , zoological journal of the linnean society 175 : 307 - 318 . click here for electronic access .
by daniel l . graf , hugh jones , anthony j . geneva , john . m . pfeiffer iii & michael w . klunzinger
published 2015 , molecular phylogenetics & evolution 85 : 1 - 9 . click here for electronic access .
invited presentation at the second international meeting on biology and conservation of freshwater bivalves , 4 - 8 october 2015 , buffalo , ny .
this slide shows the distributions of two species in the magdalena basin , colombia .
presented at the 81st annual meeting of the american malacological society , 28 - 31 august 2015 , university of michigan biological station , pellston , mi .
by kevin s . cummings , jeremy tiemann , daniel l . graf , maria cristina dreher mansur & mark h . sabaj - perez
presented at the 53rd annual meeting of the american fisheries society – illinois chapter , pere marquette state park , 3 - 5 march 2015 . also presented at the 9th biennial freshwater mollusk conservation society symposium , st . charles , missouri , 22 - 26 march 2015 .
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. . . in this classification , hyrioidea ( represented only by hyriidae ) occupy an intermediate position between the two other groups , etherioidea and unionoidea , reflecting the conflicting data from other authors concerning the position of hyriidae ( , hoeh et al . 2001 , graf & cummins 2006 ) . graf et al . ( 2015 ) presented hyriidae as sister to all other freshwater mussel families , in a position quite different from the previously one ( graf & cummings 2006 ) , however similar ( regarding to hyriidae position ) to topology presented by hoeh et al . ( 2009 ) . . . .
. . . there are around 80 species of hyriidae , occurring throughout oceania and south america , with only two or three species west of the andes ( bonetto et al . 1986 ; parada & peredo , 2002 ; graf & cummings , 2007 ; bogan , 2008 ) . hyriidae is monophyletic ( graf et al . 2015 ) and usually divided in two groups ( sub - families ) , the hyriinae , which comprises south american species , except by hyridella swainson , 1840 and some related australian species ; and velesunioninae , that comprises most australian species ( graf & cummings , 2006bieler et al . 2010 ; graf et al . 2015 ) . among hyriidae seven genera are recognized to south america : prisodon schumacher , 1817 ; paxyodon schumacher , 1817 ; callonaia simpson , 1900 ; castalia lamarck , 1819 ; castaliella simpson , 1900 ; diplodon spix in wagner , 1827 and rhipidodonta mörch , 1893 ( simone , 2006 ) ; and , nine genera to australia : hyridella ; cucumerunio iredale , 1934 ; echyridella mcmichael & hiscock , 1958 ; virgus ; velesunio iredale , 1934 ; alathyria iredale , 1934 ; lortilella iredale , 1934 ; microdontia tapparone canefri , 1883 ; westralunio iredale , 1934 ( graf & cummings , 2007 ) . . . .
. . . there are around 80 species of hyriidae , occurring throughout oceania and south america , with only two or three species west of the andes ( bonetto et al . 1986 ; parada & peredo , 2002 ; graf & cummings , 2007 ; bogan , 2008 ) . hyriidae is monophyletic ( graf et al . 2015 ) and usually divided in two groups ( sub - families ) , the hyriinae , which comprises south american species , except by hyridella swainson , 1840 and some related australian species ; and velesunioninae , that comprises most australian species ( graf & cummings , 2006bieler et al . 2010 ; graf et al . 2015 ) . among hyriidae seven genera are recognized to south america : prisodon schumacher , 1817 ; paxyodon schumacher , 1817 ; callonaia simpson , 1900 ; castalia lamarck , 1819 ; castaliella simpson , 1900 ; diplodon spix in wagner , 1827 and rhipidodonta mörch , 1893 ( simone , 2006 ) ; and , nine genera to australia : hyridella ; cucumerunio iredale , 1934 ; echyridella mcmichael & hiscock , 1958 ; virgus ; velesunio iredale , 1934 ; alathyria iredale , 1934 ; lortilella iredale , 1934 ; microdontia tapparone canefri , 1883 ; westralunio iredale , 1934 ( graf & cummings , 2007 ) . . . .
. . . 257 ma in the permian . however , the genesis of extant margaritiferids traces back to ca . 88 ma in the late an early jurassic ( mean age = 194 ma ) origin of the crown - group hyriidae was estimated previously ( graf et al . , 2015 ) , but a relatively younger age is shown in our study ( 178 ma ) . even though fewer hyriidae species were sampled and no calibration point inside this family was used in present study , the major reason contributes to the difference is the incongruence on relationships between hyriidae with the other five families of unionoida . . . .
reclassification of lamprotula rochechouartii as margaritifera rochechouartii comb . nov . ( bivalvia : margaritiferidae ) revealed by time - calibrated multi - locus phylogenetic analyses and mitochondrial phylogenomics of unionoida
. . . we focus on echyridella menziesii , the most abundant of three freshwater mussel species found in new zealand and a species that is widely distributed in streams , rivers and lakes ( marshall , fenwick , & ritchie , 2014 ) . echyridella menziesii belongs to a family of freshwater mussels ( hyriidae ) only found in the southern hemisphere ( new zealand , australia , new guinea , south america ; graf , jones , geneva , pfeiffeer , & klunzinger , 2015 ) . . . .
. . . bonetto , 1967 ; haas , 1969 ; mansur & valer , 1992 ; pimpão et al . , 2012 ) . genetic studies , based on molecular data have been carried out on freshwater bivalves from australia , north america , europe and africa , mainly to clarify systematic classifications ( graf et al . , 2014 graf et al . , , 2015 santos - neto et al . , 2016 ; lopes - lima et al . , 2017 ) , but also to evaluate their population structure , variability and demography ( hughes et al . , 2004 ; mock et al . , 2010 ; jones et al . , 2015 ; froufe et al . , 2014froufe et al . , , 2016ainoue & berg , 2017 ) . only a few genetic studies ( whelan et al . , 2011 ; graf et al . , 2015 ; santos - neto et al . , 2016 ; combosch et al . 2017 ) have included hyriidae from the amazon region , all of which were used to establish phylogenetic relationships . . . .
. . . genetic studies , based on molecular data have been carried out on freshwater bivalves from australia , north america , europe and africa , mainly to clarify systematic classifications ( graf et al . , 2014graf et al . , , 2015santos - neto et al . , 2016 ; lopes - lima et al . , 2017 ) , but also to evaluate their population structure , variability and demography ( hughes et al . , 2004 ; mock et al . , 2010 ; jones et al . , 2015 ; froufe et al . , 2014froufe et al . , , 2016ainoue & berg , 2017 ) . only a few genetic studies ( whelan et al . , 2011 ; graf et al . , 2015 ; santos - neto et al . , 2016 ; combosch et al . 2017 ) have included hyriidae from the amazon region , all of which were used to establish phylogenetic relationships . . . .
. . . whereas , molecular phylogenetics has dramatically improved our understanding of the higher level classification of the hyriidae ( graf et al . , 2015 ; santos - neto et al . , 2016 ) , our understanding of hyriid diversity at , and below , the species level , remains poor . cytochrome c oxidase subunit i ( coi ) sequences have revealed interesting patterns of freshwater bivalve population structure , both within and among distinct basins , raising awareness of the conservation needs of specific populations ( hughes et al . , 2004 ; elderkin et al . , 2007elderkin et al . , , 2008playford & walker 2008 ; mock et al . , 2010 ; froufe et al . , 2014 ) . . . .
. . . as a response , taxonomic and systematic studies of unionids that integrate conchological and anatomical analyses with molecular phylogenies have increased over the last two decades . most studies have dealt with american , european and australasian taxa ( rosenberg et al . 1994rosenberg et al . , 1997 ; graf and ófoighil 2000 ; hoeh et al . 2001 ; graf and cummings 2011 ; graf 2013 ; lopes - lima et al . 2014 ; prié and puillandre 2014 ; graf et al . 2015 ) , whereas asian taxa have largely been neglected . the monographs by haas ( 1969 ) and brandt ( 1974 ) have reported taxonomic surveys of thai species . . . .
. . . tests of phylogenetic hypotheses on the basis of other data sources , such as those derived from molecules and chromosomes , are therefore likely to be informative . however , such approaches have as yet been attempted only on a limited number of taxa and there are still very few studies in asian and african regions ( lopes - lima et al . 2014 ; marshall et al . 2014 ; graf et al . 2015 ) . several sympatric species have been recorded in numerous thai localities ( brandt 1974 ; panha 1990 ) , raising many interesting taxonomic and ecological questions . . . .
. . . taxon 28s coi 16s source locality larval type mytilidae mytilus edulis linnaeus , 1758 * z29550 gu570521 af317054 littlewood ( 1994 ) , lesser et al . ( 2010 ) , direct submission marine veliger veneridae mercenaria mercenaria ( linnaeus , 1758 ) * af131019 dq184836 dq184737 park & ó foighil ( 2000 ) , mikkelsen et al . ( 2006 ) marine veliger trigoniidae neotrigonia margaritacea ( lamarck , 1804 ) * af400695 nmu56850 dq280034 graf ( 2002 ) , hoeh et al . ( 1998 ) , giribet et al . ( 2006 ) marine veliger etheriidae etheria elliptica lamarck , 1807 kp184873 kp184897 kp184847 graf et al . ( 2015 ) zambia lasidium mycetopodidae lamproscapha ensiformis ( spix & wagner , 1827 ) kp795004 kp795021 kp795039 ansp416342 peru lasidium iridinidae chambardia wahlbergi ( krauss , 1848 ) * jn243864 jn243886 kp795040 whelan et al . ( 2011 ) , fmnh 343928 zambia lasidium hyriidae hyridella australis ( lamarck , 1819 ) kp184883 kp184907 kp184859 graf et al . ( 2015 ) . . .
. . . australia s - shaped hooked velesunio ambiguous ( philippi , 1847 ) kp184892 kp184915 kf011257 graf et al . ( 2015 ) , pfeiffer & graf ( 2013 ) australia s - shaped hooked triplodon corrugatus ( lamarck , 1819 ) kp184876 kp184900 kp184852 graf et al . ( 2015 ) peru s - shaped hooked castalia ambigua lamarck , 1819 jn243867 jn243889 kp184848 graf et al . ( 2015 ) . . .
. . . owing to their relatively limited migration and dispersal abilities , their sensitivity to changes in the environment has become evident through heavy declines in recent decades ; freshwater mussels are among the most threatened group of fauna globally ( seddon et al . 2012 ; lopes - lima et al . 2014 ) . australia ' s freshwater mussels belong to six genera , all from the hyriidae , believed to have arisen between the jurassic and cretaceous periods , with westralunio carteri as perhaps the most ancient ( graf et al . 2015 ) and the sole representative of the genus in australia ( mcmichael and hiscock 1958 ) . the taxon was described as a subspecies ( w . . . .
as members of the iucn red list mollusc specialist committee , we aim to work with collaborators to update the conservation status of freshwater mussels across australia .
we wish to determine the origin of helicoidea and sagdoidea within eupulmonata as well as family - level relationship within the superfamilies .
molecular phylogenetic analysis of tropical freshwater mussels ( mollusca : bivalvia : unionoida ) resol . . .
the freshwater mussels prisodontopsis aviculaeformis ( f . r . woodward , 1991 ) and mweruella mweruensis ( e . a . smith , 1908 ) are endemic to lake mweru and confluent rivers in zambia and the democratic republic of congo in southcentral africa . each species has traditionally been regarded as monotypic at the genus - level or above . we assessed the phylogenetic relationships of these two species together . . . [ show full abstract ]
bilaterally asymmetrical glochidia ( i . e . bivalved parasitic larvae bearing a large marginal appendage on a single valve ) have been reported from five asian freshwater mussel genera belonging to two separate subfamilies , the gonideinae ( i . e . pseudodon , solenaia , and physunio ) and rectidentinae ( i . e . contradens and trapezoideus ) . this classification requires that the bilaterally asymmetrical . . . [ show full abstract ]
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is commonly referred to as pearly mussels , naiads , or unionids . although no full accounts for the family
includes around 1 , 000 species worldwide ( bauer 2001a ) . charles torrey simpson described 1 , 172 species in 1900 and 1 , 337 in 1914 . a more recent account by fritz haas ( 1969 ) combined over 4 , 000 names into just 837 recognized species ( graf & cummings 2002 ) .
are acephalic ( no head ) , bivalved mollusks usually with the beak ( the elevated portion of the dorsal margin ) slightly anterior . when present , the pseudocardinal teeth are generally anterior to the beak . the lateral teeth , generally posterior to the beak , are parallel to the hinge line . the species in this family have a foot rather than a byssus , fibrous structures found in other mussel families . along with
does not have true siphons ( true siphons are formed when tissues between the inhalent and exhalent openings are fused and mantle aperatures are elongated ) . unlike the family
has unbranched papillae ( bumps ) . individuals vary in shape , size and coloration . adult individuals can range from 30 to 250 mm .
occur in north america , europe , asia , africa , and the indonesian archipelago ( graf and cummings , 2002 ) and can thrive in tropical to temperate climates . the most diversity is in north america , where there are approximately 286 species ( turgeon et al . , 1998 ) , mainly east of the rocky mountains ( jennings , 2000 ) . the nearly 300 species in north america are grouped into 49 genera , which make up two subfamilies :
is an example of this broad diversity . only two species are found in the interior united states ( mississippi river basin ) , and the majority of the species ( 36 currently recognized ) are found in the rivers of the southeastern atlantic coastal plain ( watters , 2001a ) . historical documentation describes mussels paving the beds of the ohio and wabash rivers ( warren , 2000 ) .
( cummings and mayer , 1992 ; graf and cummings , 2008 ; graf , 2002 ; jennings , 2000 ; turgeon , et al . , 1998 ; warren , 2000 ; watters , 2001a )
unionids are found in various permanent freshwater sources such as lakes , streams , and rivers . the family
is not found in high mountain lakes , probably due to a lack of proper fish hosts for the glochidia or poor nutrient supply ( smith 2001 ) . most species are generally found where there are coarse substrates like sand or gravel ( smith 2001 ) however , the predictive value of substrate has been questioned ( strayer and ralley , 1993 ) . in michigan , different mussel distributions may more strongly tied to surface geology in the streams ( strayer , 1983 ) . constantly shifting substrates or stream basins composed of solid rock have few mussels . rivers tend to have a more abundant food supply and higher dissolved oxygen content than bodies of water with little or no current . large rivers tend to contain a wider diversity of mussel species and larger populations than smaller streams ( cummings & mayer 1992 ) . watters ( 1992 ) found as the area of a drainage basin increases , so does the fish diversity . this relationship is likely due to the increased diversity in habitat for fish . watters ( 1992 ) also found a linear correlation between fish diversity and mussel diversity , likely due to the increase number of host fish species available .
because the shell is primarily composed of calcium carbonate , mussels prefer an aquatic habitat with an alkaline ph , an abundance of calcium , a bound carbon dioxide content of more than 15 mg / l , and a potassium level less than 7 mg / l . some species are able to tolerate an acidic ph for a short time , but eventually the acid will dissolve the shell and alter the internal chemistry of the visceral mass . calcium and carbon dioxide are important for the development of the shell , and potassium appears to be toxic .
unionids are most abundant in depths less than 2 m , but will populate waters as deep as 7 m ( smith 2001 ) . the record depth for a
specimens ranging between 7 and 14 years old and less than 53 mm long were collected from lake michigan ( reigle 1967 ) .
called
valves
( bivalved ) attached at the hinge by an elastic ligament . they have an
( beak ) along the dorsal margin and slightly anterior to the hinge and are bilaterally symmetrical along a plane running between the two valves . individuals do not have true siphons . instead , they have two to three openings in the mantle along the posterior margin that act as the inhalant and exhalant apertures ( smith 2001 ) . these openings are either papillated ( bumpy ) or crenulated ( grooved ) along the external margin . under each mantle is a gill made up of two demibranchs . each demibranch is composed of two
fused at the ventral surface but open at the dorsal surface forming a “w . ” each lamella is lined vertically with compact
, which are closed at the bottom but open into a larger , shared cavity at the top called the suprabranchial chamber . these water tubes are characteristic of
is found on the anterior end of the organism and between the demibranchs in the two valves . the majority of the median visceral mass in the posterior portion of the organism is primarily dorsal and not as confined in the anterior portion ( smith 2001 ) . unionids have a simple sensory system . their
is comprised of three pairs of ganglia : cerebropleural , pedal , and visceral . with one on each side of the esophagus , the cerebropleural ganglia are located on the posterior side of the anterior adductor muscle and are connected by a short commissure . in the foot and fused is the pair of pedal ganglia and anterior to the posterior adductor muscle is the partially fused visceral ganglia . the ganglia are connected by long commissures and each pair is the source of the nerve fibers for the surrounding organs ( smith 2001 ) . near the pedal ganglia is a pair of
, which are ovid or spherical . these statocysts are filled with fluid and lined with sensory cells . they also contain a solid sphere called a statolith ( smith 2001 ) . these mussels generally have closed statocysts and a single statolith ( meglitsch & schram 1991 ) . osphradia are specialized epithelium concentrated in two small regions on the roof of the cloacal chamber ( the posterior end of the suprabranchial chamber in the gills where it is fused ) ( smith 2001 ) . in some species , there is a spot of pigmentation near the inhalant aperture that may be photoactive ( smith 2001 ) .
adult unionids can range anywhere from 30 to 250 mm ( smith 2001 ) in length , and are just as variable in shape and color . among the common shapes are triangular , circular , rhomboidal , quadrate , trapezoidal , and elliptical ( burch 1975 ) . shape is a general description ; it cannot be heavily relied upon in the identification of species because it can vary among individuals of the same species . it is not uncommon to have a more inflated , rounded form of a species found in large rivers , while the larger , more compressed form of the same species is found in smaller streams and lakes where currents are not as strong . many genera in the subfamily
exhibit sexual dimorphism . in these species , the males are usually bluntly pointed or squared along the posterior - ventral margin , while females are broadly truncated . periostracum colors vary from yellow or tan to shades of green to dark brown or black . some have solid rays , broken rays , wavy rays , rays composed of chevrons , or even a combination of rays and spots . external shell sculpturing can also vary from one species to another and can be used to distinguish some taxa . sculptures can be one of several combinations of ridges and bumps called
nodules
or
pustules .
not all mussel species have sculpturing . nearly the entire
subfamily has smooth surfaces with the exception of ridges formed from the concentric growth rings . another exterior sculpturing that is relied upon in identification is beak sculpture . beak sculptures range from numerous fine concentric ridges to a few distinctive bars to double - looped or v - shaped ridges . in some cases , the difference in beak sculpture is the best way to distinguish between two species . other exterior shell characteristics may include a prominent posterior ridge extending from beak to posterior - ventral margin , a unique texture to the periostracum , or a wing - like structure extending from the dorsal margin .
are the parasitic stage of the larvae and are generally dependent on a host to survive . mature glochidia range from 0 . 05 to 0 . 5 mm in diameter . they are bivalves , which vary in shape from triangular , circular , oblong , or ( in
only ) ax head shaped and are typically attached by a single adductor muscle . most glochidia have sensory hairs lining their mantle and a larval thread protruding from the open valves , which may allow them to attach to the host . many species have hook - like structures to allow them to attach to the fins or skin of the fish . those species without hooks usually attach to the gills .
measurements are generally taken of the length , height , and width . the length is the distance from the anterior to the posterior margin . the height is the distance from dorsal to ventral margin , usually at the beak . width is the widest point when the mussel valves are together , which is usually below the beaks . in addition , some identification keys will use the length to height ratio as a way to distinguish some species .
embryonic unionids develop within the marsupia , or specialized portions of the gills , of the female . once fully developed , they are
from the female and must attach to the gills or fins of a fish host within a few days or they will die .
are the only two species capable of direct development without a host ( watters 1994c ) . only one species ,
. many unionids are species - specific , requiring one or a narrow range of species . if attached to the wrong species , the glochidia will die as a result of the fish ' s immune system response ( watters 1998 ) . within a couple of days , the hosts’ dermal tissue will encapsulate each glochidium forming a nodular cyst . while encysted , the glochidia will metamorphose , allowing the organs to develop more like an adult’s organs ( meglitsch & schram 1991 ) . there is a mortality rate of over 99 . 99 % from the time the glochidia are released from the mother to the time in which the metamorphosed juveniles settle in the sediments ( jansen et al 2001 ) .
( jansen , et al . , 2001 ; meglitsch and schram , 1991 ; watters , 1994c ; watters , 1998 )
after an average of 10 - 30 days ( the record is 190 days ) , the metamorphosis will be complete and the glochidia will break from the cysts and drop from the host . the third and final stage of development occurs in the sediments of the stream or lake and may last anywhere from one to eight years before the juvenile is sexually mature . in this juvenile stage , the young mussel will complete its internal development , create the adult shell , and begin to live independently in the stream or lake .
as in most bivalves , the shell is composed of three layers : the periostracum , the prismatic layer , and the nacre . the periostracum is the outermost layer and is composed of an organic material . the prismatic layer is the middle layer and is composed of thin blocks of a prism - like calcium carbonate , which are oriented perpendicular to the mantle and the other two layers . the nacre , or mother of pearl , is the innermost layer , which is composed of thin , alternating , laminae ( flakes or sheets ) of calcium carbonate and an organic material ( smith 2001 ) . the mantle is responsible for generating new shell as the mussel ages . a mantle flap is pressed against the interior of each valve and ends in three folds . the periostracum forms at the outer margin and the prismatic layer forms at the outer border . the nacre forms along the entire surface of the mantle .
form where the muscle attaches to the shell , disrupting the formation of the nacre . instead of the shell forming along the dorsal edge where the hinge is located , an elastic hinge ligament composed of conchiolin ( a protein - rich substance ) forms , binding the two valves together ( meglitsch & schram 1991 ) .
. because new shell is added along the entire edge of the mantle , concentric rings form around the beak . in some species , these rings may be grouped closer together in some areas than others , forming ridges . these ridges indicate the period of diapause during the winter or unfavorable environmental conditions , such as lower water level or lack of food . the period of growth in northern populations is typically from april to september . the growth rate depends mostly on environmental conditions such as water temperature , food supply , and the chemical composition of the water . many mussel species are capable of growing 30 to 80 mm every two growing seasons .
a few species are occasionally or permanently simultaneous hermaphrodites ( bauer 1987 ) , but in most cases , unionid sexes are separate . bauer ( 1987 ) suggested that hermaphroditism occurs when the population density is low or gene flow is limited . in these cases , the female is the only one of the two sexes that can become hermaphroditic . despite the dioecious nature of most mussels , males and females do not make contact with each other . males produce sperm year round and
during the time of year when females ovulate ( matteson 1948 ) . this simultaneous release of gametes may be triggered by a change in the water temperature and the intensity of light in the environment . the male’s sperm leaves the suprabranchial chamber of each demibranch and exits the organism through the exhalant aperture to be carried by the water current to a nearby female . because sperm cannot swim against the current , the receiving female must be downstream ( watters 1994a ) . the sperm enters the female through the inhalant aperture and fertilizes the eggs stored in the water tubes of the demibranch’s lamellae ( smith 2001 ) .
depending on the species , sexual maturity is reached between one and eight years ( smith 2001 ) . gamete production is initiated by a change in the water temperature surrounding the mussel ( watters 1998 ) . annual gametogenesis and gravidity may occur throughout the year or during certain seasons depending on latitude . the more northern populations tend to be gravid for a few months or all winter long and release the glochidia in the spring . there are a few species that release the glochidia in the fall . in many cases , southern populations are not restricted to reproducing during certain seasons . the number of larvae developing in one female at a time may range from several thousand in some of the smaller
genera to possibly over 1 million . the maximum amount of glochidia in one female is unknown , but tankersley and dimock ( 1992 ) recorded nearly 1 million in a
, contains species which have produced more than 3 million per individual ( smith 2001 ) . bradytictic ( long term ) breeders will maintain the glochidia within the marsupia , the specialized portions of the gills , until the following spring or summer before
. tachytictic ( short term ) breeders will release the glochidia in the same year , usually by july or august ( watters 1998 ) . matteson ( 1948 ) was convinced that the membrane surrounding the developing embryos provides all of the necessary nutrients , rather than the female transferring food to the developing young . his conclusion was based on a lack of connective structure from the gills to the young and that the fertilization membrane surrounding each embryo , which prevents the passing of any materials , remains until development is complete .
unionid embryos spend the first stage of development in the marsupial portion of the female unionid ' s gills , where they develop into glochidia , the parasitic stage . once the first stage is complete , usually in the spring , the female will
into the water to begin the second stage as a parasite . because glochidial mortality is high , many unionids have developed specialized methods of attracting fish to the mother before the glochidia are released , increasing the chances the larvae can attach to a host . some of these species extend the glochidia encapsulated in conglutinates ( chamberlain 1934 ) . these conglutinates ( sacs ) are attached to the parent organism and move in the current like worms . this encapsulated appendage acts as a lure to attract the host fish , which then eats the glochidia freeing them from the capsule and allowing them to attach to the gills of the fish . other species use a modified mantle flap to attract the fish . this flap mimics the prey of the potential host fish . the glochidia are sensitive enough to attach themselves to the fish as soon as contact is made .
for small organisms , unionids are long - lived , living an average of 10 or more years ( cummings & mayer 1992 ) . some genera live only 8 to 9 years , while others can live up to 10 to 15 years ( smith 2001 ) . given the proper conditions , many species can live up to 20 or 30 years ( watters 1998 ) . bauer ( 2001b ) suggested life span is dependent upon metabolic rate . mussels with a higher metabolic rate tend to have a shorter life span . those unionids in larger rivers or streams would have a higher metabolic rate due to the abundance of food , and would be expected to have a short life . unionids that thrive further upstream may have a longer lifespan because they would have adapted to a limited food supply by decreasing their metabolic rate . although metabolic rate is a key factor affecting longevity in some species , it is not a universal constant . some species with similar metabolic rates may have very different lifespans .
for the most part , mussels are sedentary , but they are capable of a restricted form of locomotion . they move around by a series of muscular motions of the
located at the anterior end of each individual . the foot is thrust forward first . it then swells and shortens at the same time , causing the body and shell to pull forward slightly . this process is repeated until the mussel has reached its destination . some species have been recorded to move up to several feet within an hour . researchers are still unsure what causes this migration , but they suspect the movement is caused by a drop in water level or some other unfavorable change in the surrounding environment .
unionids are solitary organisms . the only intra - or inter - species interactions occur during reproduction . once they drop from the host , the mussel becomes a solitary individual and live partially buried in the sediments . as juveniles , mussels burrow into the sediments along the bottom of the stream or lake , which protects them from predators . once mature , more of the organism must protrude from the substrate in order for the inhalant and exhalant apertures to bring in and expel water . because more of the shell is visible , they are more susceptible to predation .
during winter months and aestivation periods ( matteson 1955 ; van der schalie 1940 ) , mussels will burrow into the substrate until only the apertures are protruding . they then go into a state of dormancy where the apertures only open on occasion . some genera are able to survive in this dormant state among the dry to moist sediments for months at a time ( smith 2001 ) .


elimia tenera , formerly known as goniobasis tenera , is an extinct species of freshwater snail with an operculum , in the aquatic gastropod mollusk family pleuroceridae .

this species flourished during the eocene and is now known only from the fossil record .

the genus name elimia was restored to this species in 1975 ; formerly it was placed in goniobasis .

elimia tenera

aquamarine | elimia tenera fossil | raw aquamarine & elimia tenera mismatched earring studs . mermaid earrings . boho jewelry .
turritella agate slab , elimia agate slice for cabbing or display , fossilized elimia tenera , 91x64x6 . 7mm
paleo & geo topics : comments by r . l . squires : elimia tenera : a commonly misidentified eocene freshwater snail
elimia tenera , green river formation , usa , eocene era ( 45 mya ) - 18 . 8g | fossils | pinterest | green river
elimia tenera , green river formation , usa , eocene era ( 45 mya ) - 15 . 4g | fossils | pinterest | green river
click the button below to add the turritella ( elimia tenera ) fossil - 34 to 56 mya - actual authentic fossil to your wish list .
this rock ( 77 mm width ) is fully packed with specimens of e . tenera .
elimia tenera : specimen on the left ( 19 mm height ) shows the spiral ribs , and the specimen on the right ( 14 mm height ) shows both spiral and radial ribs .
turritella agate , elimia tenera fossil shell , 6mm ( 6 . 4mm ) round beads , 16 inch , full strand , approx 65 beads , hole 1mm , a + quality ( 421054002 )
named
turritella
in error decades ago . the correct name is
elimia agate .
this polished slab ( 37 mm width ) shows only the cross section of shells of e . tenera .
so , next time you visit your favorite rock and fossil shop or show , ask for an agatized elimia tenera cabechon . it is very likely no one will know what you are talking about . but you will !
rather , the green river formation fresh water snail species is elimia tenera , and is a member of the pleuroteridae family of gastropods . the best preserved specimens are found in the laney member of the green river formation in sweetwater county , wyoming . elimia tenera are prolifically preserved in regions of southern wyoming , northern colorado and northeastern utah where near shore lake beds were silicified during burial . intermittent volcanic eruptions likely provided the hot silica - rich ground waters responsible for shallow formation of chalcedony in a subtropical environment where the gastropods thrived .
elimia tenera , which used to be ( and incorrectly ) called goniobasis tenera , is a freshwater snail that lived in shallow subtropical lakes with intermittent volcanic eruptions nearby . this gastropod is of eocene age and is commonly found in the laney member of the green river formation in utah . this is the same formation that famously has many very well preserved fish , insect , leaf , and other fossils .
over the years , as i have viewed various collections of fossils , i have come across specimens of a small fossil gastropod that occur in great abundance . rocks containing these shells can be found for sale in rock shops or online , and the shells are commonly and incorrectly called “ turritella agate . ” these rocks do not consist of turritella ; rather they consists of specimens of the freshwater gastropod elimia tenera ( hall , 1845 ) , which have been preserved in chalcedony . actual specimens of turritella can be much larger , possess only spiral ribs , and are known only from shallow - marine deposits . elimia tenera has both radial and spiral ribs , and the aperture of elimia is quite unlike that of turritella .
abundant plants and algae grew on the margins of these lakes , providing a perfect habitat and food source for elimia tenera , the freshwater snail . when the snails died , their shells sank to the bottom of the lake . the snails were so prolific that entire lenses of sediment were composed almost entirely of their shells .
this organic gem material was incorrectly named decades ago when the christener thought that the spectacular spiral - shaped gastropod ( snail ) fossils entombed within the stone were members of the marine turritella genus . that was a mistake . instead , the fossils are of the freshwater snail , elimia tenera , a member of the pleuroceridae family .
if you want to learn more about elimia tenera and the best name for turritella agate , we recommend a visit to the paleontological research institution - people who know what they are talking about when it comes to fossils . their article on turritella agate was authored by dr . warren d . allmon , director of the institution .
the rock shown above is lacustrine fossiliferous chert packed with fossil snails . this material is popular with rockhounds and lapidarists , who call it
turritella agate
. well , it ' s not agate - it ' s fossiliferous chert . and the snails aren ' t turritella , they are elimia tenera ( animalia , mollusca , gastropoda , cerithioidea , pleuroceridae ) .
turritella agate is a type of chalcedony rich sedimentary rock from wyoming usa . it is characterized by the distinct snail shell - like creamy coloured markings within a mainly dark brown / black base . the creamy patterns are created by , and composed of , the silicated fossilized remains of an extinct type of freshwater snail , namely elimia tenera , from the turritella genus .
these three specimens of e . tenera are internal casts ( i . e . , each one shows only the interior of a shell , which was filled with chalcedony ) . the largest specimen is 14 mm height .
there has been considerable disagreement in blogs and websites as to whether or not the e . tenera specimens , found in rock shops , have been replaced by chalcedony or agate . technically speaking , chalcedony is the “culprit . ” it is a microcrystalline form of silica , and chalcedony has many varieties , including agate , which commonly has multi - colored curved or angular banding . the specimens of e . tenera that i have seen were replaced by a fairly uniform brown or gray color of “ordinary” chalcedony and not replaced by the more eye - catching , beautiful colors typically associated with agate .
turritella agate / elimia agate : a close - up photo of a sawn surface of turritella agate showing numerous spiral - shaped snail shells . this type of view shows how the internal cavities of the shells and the voids between the shells have all been infilled with the translucent - to - transparent agate . this view is about two inches across .
if you go into a rock shop or a gem , mineral , and fossil show and ask for
elimia agate ,
a lot of people will say that they have never heard of it . but , if you ask for turritella , almost everyone around you will know what it is . the incorrect name is that well - entrenched in the lapidary trade .
before the correct name was realized and widely published , the gem material became quite popular and the name
turritella
went wild in lapidary magazines , gem , mineral , and fossil books , catalogs , and exhibits . today it is typically seen without corrective note in all of those sources , along with websites , online auctions , and computer software . only a fraction of the people who have collected the material , cut it into cabochons , sold it , bought it , or worn it in jewelry have any knowledge that elimia is a more appropriate name .
molluscan taxa and their paleoecological associations appear to remain uniform throughout deposition of the formation , except for the large planorbid biomphalaria pseudoammonius , which occurs only in the bridgerian - aged rocks of the formation . living forms of the most common freshwater taxa elimia , viviparus , and the unionids ) do not now naturally occur in the rocky mountains , but occur in two separated regions : one in the eastern mississippi river drainages , the other in the pacific northwest . this distribution reflects the shift from perennial warm waters in the eocene to cooler , largely intermittent waters in the post - eocene .
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i thought you might be interested in this item at urltoken title : north american freshwater snails author : j b burch publisher : hamburg , mich . : malacological publications , ©1989 . oclc : 20559611
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online version : burch , j . b . ( john bayard ) , 1929 - north american freshwater snails . hamburg , mich . : malacological publications , ©1989 ( ocolc ) 767787615
preface v i . introduction 1 ii . systematics , nomenclature , indentification and morphology 7 - systematics 7 - nomenclature 18 - identification and morphology 25 iii . habitats and distribution 74 - habitats 74 - distribution 76 iv . species list , ranges and illustrations 81 - family neritinidae [ neritidae ] 81 - family valvatidae 81 - family viviparidae 84 - family ampullariidae [ pilidae ] 90 - family bithyniidae 92 - family micromelaniidae 92 - family hydrobiidae 92 - family pomatiopsidae 130 - family thiaridae 130 - family pleuroceridae 131 - family acroloxidae 170 - family lymnaeidae 170 - family physidae 182 - family planorbidae 194 - family ancylidae 212 v . identification keys to the freshwater gastropods of north america 217 - families and higher taxa 217 - family neritidae [ neritinidae ] 223 - family valvatidae 223 - family viviparidae 227 - family ampullariidae [ pilidae ] 230 - family bithyniidae 230 - family micromelaniidae 231 - family hydrobiidae 231 - family pomatiopsidae 239 - family thiaridae 240 - family pleuroceridae 241 - family acroloxidae 247 - family lymnaeidae 247 - family physidae 253 - family planorbidae 254 - family ancylidae 261 vi . generic synonymy 264 vii . supplemental notes 268 viii . glossary 285 ix . references 77 , 293 x . index 338 corrigenda 80 , 283
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north american freshwater snails / j b burch ; hamburg , mich . : malacological publications , ©1989 .
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author : hobart m . king , ph . d . , gia graduate gemologist
turritella agate is the popular name used for a brown , translucent , fossiliferous agate found in the green river formation of wyoming . it is very easy to recognize because it contains large fossil snails that stand out in a white - to - tan color that contrasts with the brownish agate .
it is possible that the misnamed turritella is the best - known fossil from the green river formation .
turritella agate cabochon : a cabochon cut from turritella agate that features one of the spiral - shaped snail shells . this cab is about 1 1 / 2 by 1 inch in size .
about 50 million years ago , during the eocene epoch , the young rocky mountains were almost finished growing , and the landscape of what is now parts of colorado , utah , and wyoming consisted of rugged mountains separated by broad intermountain basins . rains falling on the slopes of these mountains ran off of the land and collected into streams that carried sand , silt , mud , and dissolved materials down into the lakes that occupied the intermountain basins . over time , these sediments began filling the lakes , and many types of fossils were preserved within them .
after these layers were buried , groundwater moved through the sediments . small amounts of dissolved microcrystalline silica in the groundwater began to precipitate , possibly in the form of a gel , within the cavities of the snail shells and the empty spaces between them . over time , the entire mass of fossils was silicified , forming the brown fossiliferous agate ( also known as chalcedony ) that we know today as turritella agate .
the green river formation is one of the best - known rock units in the world for its fossils . some geologists call it a
lagerst├ątte ,
a name given to a rock unit that is exceptionally rich in fossils . spectacular fish , plant , insect , and animal fossils have been found in the green river formation .
turritella slab : a slab of turritella agate about six inches in width and 3 / 8 inch thick . slabs like this are used to cut cabochons . the lapidary selects a nice scene in the slab , saws a rough outline , and grinds the material into a cab .
for at least the past fifty years , turritella agate has been prized as a unique and beautiful gem material . when it is completely silicified , it can be sawn into slabs that are polished and used for bookends , desk sets , clock faces , and other lapidary craft items .
many lapidaries mark ovals , circles , squares and other shapes on the slabs and cut them into cabochons . these make great pendants , belt buckles , bolos , ring stones , and earrings . scraps and pieces too small to slab or make other items with can be placed in a rock tumbler to produce some of the most interesting tumbled stones .
people who see these beautiful projects marvel that so many spectacular fossils are preserved in the rock . they are also surprised by the cross - sections of the fossils that are visible in great detail on the slabs , cabs , and tumbled stones . turritella is one of the most fascinating gem materials and a lesson in snail anatomy .
the rock material that contains the fossil snails ranges from a shale to a sandstone . some of it has been silicified into a dense agate that is free of voids and serves as an excellent gem material . however , most of the material is only somewhat silicified , or unsilicified .
when purchasing or collecting material for lapidary work , it must be carefully inspected to be sure that it is fully silicified and that the fossils are firmly cemented into the rock . some of the vendors who sell it do not know the qualities that are needed for lapidary work . incompletely silicified material is a waste of money and time . it is frustrating to cut , yields a low - quality product , and doesn ' t even make nice tumbled stones .
turritella agate rough : another close - up photo of turritella agate . the width of this view is about two inches .
images , code , and content on this website are property of urltoken and are protected by copyright law .
dr . squires shares his enthusiasm for interesting paleontologic and geologic topics with the general public .
today is confined entirely to north american fresh waters : the eastern united states and into texas and from southern canada to florida . pleurocerids might be relicts ( “living fossils” ) from earlier geologic times ( paleozoic ? ) in eastern north america .
i taught paleontology for 40 years at california state university northridge . my on - going research concerns fossil mollusks ( i . e . , snails and clams ) that can be found in cretaceous and cenozoic rocks along the west coast of north america .
all images and text are copyrighted by r . squires , unless otherwise noted . . simple theme . powered by blogger .
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turritella agate pendant . turritella necklace . fossil necklace . fossil jewelry . protection stone . gift for him .
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, department of geology and geological engineering , univ of north dakota , box 8358 , grand forks , nd 58202 , joseph _ hartman @ und . nodak . edu , hanley , john h , u . s . geol survey , denver federal center , box 25046 , denver , co 80225 , good , steven c . , department of geology & astronomy , west chester univ , west chester , pa 19383 , and evanoff , emmett , university of colorado museum , univ colorado - boulder , campus box 265 , boulder , co 80309 - 0265
the shells of freshwater and terrestrial mollusks occur in all facies of the wasatchian and bridgerian - age green river formation and can be so abundant as to form coquinas . fossil assemblages include freshwater gastropods , terrestrial ( subaerial ) gastropods , freshwater mussels , and fingernail clams .
. these two gill - bearing snails are most abundant in the high - energy shore facies of the formation . other gastropods include species of
( heterostropha ) . the latter are typically the only gastropods that occur in the sublittoral oil shales . freshwater pulmonate gastropods are numerically rare in the formation but include species of
. the pulmonate gastropods typically occur in near - shore facies and in pond deposits in the wasatch and bridger formations lateral to the green river formation .
is most abundant in the near - shore facies . the highly alkaline chemistries of the green river lakes allowed for the preservation of the glochidium on adult shells of
is most abundant in the sublittoral facies and can occur in the oil shales .
© copyright 2002 the geological society of america ( gsa ) , all rights reserved . permission is hereby granted to the author ( s ) of this abstract to reproduce and distribute it freely , for noncommercial purposes . permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education , including classroom use , providing all reproductions include the complete content shown here , including the author information . all other forms of reproduction and / or transmittal are prohibited without written permission from gsa copyright permissions .
we interpret the lower laclede bed to record deposition in a balanced - fill lake basin , in which lakes of varying salinity expanded and contracted across a low - relief basin floor . the preservation of shoreline and alluvial facies in the northeastern part of the transect suggest maximum lake depths of ~ 50 m or less , based on analogy to the modern bear river delta in utah . we interpret the upper laclede bed to record deposition in an overfilled lake basin , that was continuously occupied by a relatively stable , freshwater lake with an outlet to the south .
previous studies concluded that the transition to overfilled conditions resulted from capture of the idaho river . the results of this study suggest a more complex process of continuous watershed expansion that occurred throughout laney member deposition . based on 87s r / 86 sr ratios , the base of the laney member in the bridger basin appears to be slightly older than in the washakie basin . capture of the idaho river did trigger the shift to overfilled conditions however , and southward spillage of lake gosiute caused lakes in the piceance creek and uinta basins to merge and deposit the highly organic - rich mahogany zone . detritus from the challis volcanic field eventually filled in lake gosiute , and was then carried downstream to partly fill lake uinta .
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we thank b . l . beard , k . m . bohacs , h . p . buchheim , g . grabowski , c . m . johnson , j . t . pietras , and m . e . smith for their helpful assistance , advice , and discussions concerning the laney member . e . drew , e . parcher - wartes , and j . van alstine served as tireless field assistants during this project , and a . devaughn assisted with laboratory analyses . we are grateful for funding received from conoco , texaco , the u . s . national science foundation ( ear - 9406684 and ear - 9628549 to c . m . johnson ) , the donors of the petroleum research fund of the american chemical society , the j . david love wyoming field geology fellowship , and the university of wisconsin - madison department of geoscience , and the morgridge distinguished graduate fellowship . we also thank m . e . smith for thoughtfully reviewing the manuscript .
aswasereelert w , meyers sr , carroll ar , peters se , smith me , feigl kl ( 2013 ) basin - scale cyclostratigraphy of the green river formation , wyoming . geol soc am bull 125 : 216–228
baker pa , kastner m ( 1981 ) constraints on the formation of sedimentary dolomite . science 213 : 214–216
behr h ( 2002 ) magaiite and magadi chert ; a critical analysis of the silica sediments in the lake magadi basin , kenya . in : renaut rw , ashley g ( eds ) sedimentation in continental rifts , vol 73 , society for sedimentary geology ( sepm ) special publication . sepm ( society for sedimentary geology ) , tulsa , pp 257–273
bohacs km ( 1998 ) contrasting expressions of depositional sequences in mudrocks from marine to nonmarine environs . in : schieber j , zimmerlie w , sethi p ( eds ) mudstones and shales , v . 1 , characteristics at the basin scale . schweizerbart’sche verlagsbuchhandlung , stuttgart , pp 32–77
bohacs km , carroll ar , neal je , mankiewicz pj ( 2000 ) lake - basin type , source potential , and hydrocarbon character : an integrated sequence - stratigraphic - geochemical framework . in : gierlowski - kordesch eh , kelts kr ( eds ) lake basins through space and time , vol 46 , american association of petroleum geologists studies in geology . american association of petroleum geologists , tulsa , pp 3–34
bradley wh ( 1929 ) the varves and climate of the green river epoch . u . s . geological survey professional paper 158 - e .
bradley wh ( 1964 ) the geology of the green river formation and associated eocene rocks in southwestern wyoming and adjacent parts of colorado and utah . u . s . geological survey professional paper 496 - a .
braunagel lh , stanley ko ( 1977 ) origin of variegated redbeds in the cathedral bluffs tongue of the wasatch formation ( eocene ) , wyoming . j sediment petrol 47 : 1201–1219
buchheim hp ( 1978 ) paleolimnology of the laney member of the eocene green river formation . phd thesis , university of wyoming , laramie , 101 p
buchheim hp , surdam rc ( 1977 ) fossil catfish and the depositional environment of the green river formation , wyoming . geology 5 : 196–198
carroll ar , bohacs km ( 1999 ) stratigraphic classification of ancient lakes : balancing tectonic and climatic controls . geology 27 : 99–102
carroll ar , doebbert ac , booth al , chamberlain cp , rhodes - carson mk , smith me , johnson cm , beard bl ( 2008 ) capture of high - altitude precipitation by a low - altitude eocene lake , western u . s . geology 36 : 791–794
casanova j , hillaire - marcel c ( 1992 ) late holocene hydrological history of lake tanganyika , east africa , from isotopic data on fossil stromatolites . palaeogeogr palaeoclimatol palaeoecol 91 : 35–48
chetel lm , carroll ar ( 2010 ) terminal infill of eocene lake gosiute , wyoming , usa . j sediment res 80 : 492–514
chetel l , janecke su , carroll ar , beard bl , johnson cm , singer bs ( 2011 ) paleographic reconstruction of the eocene idaho river , north american cordillera . geol soc am bull 123 : 71–88
cohen as , thouin c ( 1987 ) near - shore carbonate deposits in lake tanganyika . geology 15 : 414–418
demaison dj , moore gt ( 1980 ) anoxic environments and oil source bed genesis . aapg bull 64 : 1179–1209
desborough ga ( 1978 ) a biogenic - chemical stratified lake model for the origin of oil shale of the green river formation : an alternative to the playa - lake model . geol soc am bull 89 : 961–971
dickinson wr , klute ma , hayes mj , janecke su , lundin er , mckittrick ma , olivares md ( 1988 ) paleogeographic and paleotectonic setting of laramide sedimentary basins in the central rocky mountain region . geol soc am bull 100 : 1023–1039
doebbert ac , carroll ar , mulch a , chetel lm , chamberlain cp ( 2010 ) geomorphic controls on lacustrine isotopic compositions : evidence from the laney member , green river formation , wyoming . geol soc am bull 122 : 236–252
doebbert ac , johnson cm , carroll ar , beard bl , pietras jt , rhodes - carson mk , norsted b , throckmorton la ( 2014 ) controls on sr isotopic evolution in lacustrine systems : eocene green river formation , wyoming . chem geol 380 : 172–179
eggleston jr , dean we ( 1976 ) freshwater stromatolitic biotherms in green lake , new york . in : walker mr ( ed ) stromatolites . elsevier , amsterdam , pp 479–488
eugster hp ( 1967 ) hydrous sodium silicates from lake magadi , kenya ; precursors of bedded chert . science 157 : 1177–1180
eugster hp ( 1969 ) inorganic bedded cherts from the magadi area . contrib mineral petrol 22 : 2–31
fischer ag , roberts lt ( 1991 ) cyclicity in the green river formation ( lacustrine eocene ) of wyoming . j sediment petrol 61 : 1146–1154
halley rb ( 1976 ) textural variation within great salt lake algal mounds . in : walker mr ( ed ) stromotolites . elsevier , amsterdam , pp 435–445
horsfield b , curry dj , bohacs km , littke r , rullkötter j , schenk hj , radke m , schaefer rg , carroll ar , isaksen g , witte eg ( 1994 ) organic geochemistry of freshwater and alkaline lacustrine sediments in the green river formation of the washakie basin , wyoming , u . s . a . org geochem 22 : 415–440
kelts kr , hsü kj ( 1978 ) freshwater carbonate sedimentation . in : lerman a ( ed ) lakes : chemistry , geology , and physics . springer , berlin , pp 295–323
kornegay gl , surdam rc ( 1980 ) the laney member of the green river formation , sand wash basin , colorado , and its relationship to wyoming . in : hollis s ( ed ) stratigraphy of wyoming . wyoming geological association 31st annual field conference guidebook , pp 191–204
ludlam sd ( 1969 ) fayetteville green lake , new york ; 3 . the laminated sediments . limnol oceanogr 14 : 848–857
ma l ( 2006 ) origin of dolomite in the green river formation . university of houston ph . d . dissertation , 336 p
machlus ml , olsen pe , christie - blick n , hemming sr ( 2008 ) spectral analysis of the lower eocene wilkins peak member , green river formation , wyoming : support for milankovitch cyclicity . earth planet sci lett 268 : 64–75
machlus ml , ramezani j , bowring sa , hemming sr , tsukui k , clyde wc ( 2015 ) a strategy for cross - calibrating u–pb chronology and astrochronology of sedimentary sequences : an example from the green river formation , wyoming , usa . earth planet sci lett 413 : 70–78
meyers sr ( 2008 ) resolving milankovitchian controversies : the triassic latemar limestone and the eocene green river formation . geology 36 : 319–322
murphy jt , lowenstein tk , pietras jt ( 2014 ) preservation of primary lake signatures in alkaline earth carbonates of the eocene green river wilkins peak - laney member transition zone . sediment geol 314 : 75–91
platt nh , wright vp ( 1991 ) lacustrine carbonates : facies models , facies distributions and hydrocarbon aspects . in : anadón p , cabrera l , kelts k ( eds ) lacustrine facies analysis , vol 13 , international association of sedimentologists special publication . blackwell scientific publications , oxford / boston , pp 57–74
rhodes mk , carroll ar , pietras jt , beard bl , johnson cm ( 2002 ) strontium isotope record of paleohydrology and continental weathering , eocene green river formation , wyoming . geology 30 ( 2 ) : 167–170
roehler hw ( 1973 ) stratigraphic divisions and geologic history of the laney member of the green river formation in the washakie basin in southwestern wyoming . u . s . geological survey bulletin 1372 - e .
roehler hw ( 1992 ) correlation , composition , areal distribution , and thickness of eocene stratigraphic units , greater green river basin , wyoming , utah , and colorado . u . s . geological survey professional paper 1506 - e .
roehler hw ( 1993 ) eocene climates , depositional environments , and geography , greater green river basin , wyoming , utah , and colorado . u . s . geological survey professional paper 1506 - f .
schultz c , buchheim hp , awramik s ( 2004 ) a high resolution archive of lake dynamics preserved in the stromatolites of the laney member of the green river formation ( eocene ) . geol soc am abstr progr 36 : 285
ar geochronology of the eocene green river formation , wyoming . geol soc am bull 115 : 549–565
smith me , carroll ar , singer bs ( 2008 ) synoptic reconstruction of a major ancient lake system : eocene green river formation , western united states . geol soc am bull 120 : 54–84
ar , u - pb , and astronomical ages from the green river formation . geology 38 : 527–530
smith me , jicha br , carroll ar , cassel ej , scott jj ( 2014 ) paleogeographic record of eocene farallon slab rollback beneath western north america . geology 42 : 1039–1042
stanley ko , surdam rc ( 1978 ) sedimentation on the front of eocene gilbert - type deltas , washakie basin , wyoming . j sediment petrol 48 : 557–573
surdam rc , stanley ko ( 1979 ) lacustrine sedimentation during the culminating phase of eocene lake gosiute , wyoming ( green river formation ) . geol soc am bull 90 : 93–110
surdam rc , stanley ko ( 1980 ) effects of changes in drainage - basin boundaries on sedimentation in eocene lakes gosiute and uinta of wyoming , utah , and colorado . geology 8 : 135–139
talbot mr , allen pa ( 1996 ) lakes , 3 . in : reading hg ( ed ) sedimentary environments ; processes , facies and stratigraphy . blackwell , oxford , pp 83–124
van wagoner jc , posamentier hw , mitchum rm , vail pr , sarg jf , loutit ts , hardenbol j ( 1988 ) an overview of sequence stratigraphy and key definitions . in : wilgus cw et al ( eds ) sea level changes : an integrated approach , vol 42 , sepm special publication . society of economic paleontologists and mineralogists , tulsa , pp 39–45
winland hd , matthews rk ( 1974 ) origin and significance of grapestone , bahama islands . j sediment petrol 44 : 921–927
wolfbauer ca , surdam rc ( 1974 ) origin of nonmarine dolomite in eocene lake gosiute , green river basin , wyoming . geol soc am bull 85 : 1733–1740
rhodes m . k . , carroll a . r . ( 2015 ) lake type transition from balanced - fill to overfilled : laney member , green river formation , washakie basin , wyoming . in : smith m . , carroll a . ( eds ) stratigraphy and paleolimnology of the green river formation , western usa . syntheses in limnogeology , vol 1 . springer , dordrecht
green river fossil bat : this 5 . 5 inch long bat is the most primitive bat known . claws on each finger of its wings indicate it was probably an agile climber and crawled along and under tree branches searching for insects . national park service photo . enlarge image .
the green river formation has yielded some of the best - preserved and oldest fossil bats ever found . it has also produced a variety of other unusual fossils such as turtles , crayfish , and horses . the photos shown below are by the national park service - fossil butte national monument .
green river fossil turtle : this 1 . 7 meter ( 5 foot 6 inch ) softshell turtle is one of the largest turtles from fossil lake . during the eocene , trionychid turtles reached maximum size . today , north america ' s largest softshell turtles reach 51 cm ( 20 inches ) in length . national park service photo . enlarge image .
green river fossil turtle : this ten - inch - long turtle belongs to the baenidae family , an extinct north american group . shell characteristics , a very long tail and recurved claws suggest they were strong bottom - walking turtles . national park service photo . enlarge image .
green river fossil horse : most mammal fossils consist of teeth and bone fragments . this fully - articulated early horse is an extremely rare find and to date , the only horse found in the green river formation . national park service photo . enlarge image .
green river fossil crayfish : crayfish lived in the shallow , near - shore water of fossil lake . procambarus is known only from the eocene deposits of fossil lake . its closest living relative , austrocambarus , is found in mexico . national park service photo . enlarge image .
green river fossil stingray : heliobatis radians had small teeth for crushing snails and other mollusks and barbed spines on the tail for defense . national park service photo . enlarge image .
dacite - a light - colored extrusive igneous rock intermediate between rhyolite and andesite .
kick ' em jenny is a submarine volcano and one of the most active on the caribbean plate .
ash plume at kilauea caused by explosions in the summit crater rise high into the atmosphere .
minerals : information about ore minerals , gem materials and rock - forming minerals .
plate tectonics - articles and maps about plate tectonics and the interior of earth .
cleoniceras ammonite fossil , middle cretaceous ( 110 mya ) , tulear , madagascar - 13 . 8g | fossils | pinterest | ammonite
polished horn coral fossil , western sahara , morocco , devonian ( 380 mya ) - 7 . 1g | fossils | pinterest | western sahara
turritella agate
from the eocene of wyoming , usa . ( 5 . 7 cm across along the base )
of all the molluscs , the gastropods ( snails ) have made the most ecological adaptations . they can be found in almost all fundamental environments : marine , freshwater , terrestrial . most gastropods live in the ocean , and have a single , asymmetrically coiled , external shell of calcium carbonate ( caco3 - usually aragonite ) . the hard calcareous shell is the most easily fossilized part of the gastropod . the soft parts of a snail ( the “slug” portion ) include a well developed head having eyes , tentacles , and a mouth , and a well developed , strong , muscular foot used principally for locomotion . the shell is carried upright on the snail’s back , or is partially dragged behind . when threatened by a predator , many snails can retract their soft parts into the shell’s interior for protection .
many fossil snails in the paleozoic rock record are often not well preserved , or are preserved as internal molds . the original aragonite of many gastropod shells is not stable on geologic time scales , and often recrystallizes or dissolves completely away . fossil snail shells in mesozoic and cenozoic rocks are usually better preserved .
sometimes things get named too fast and once labeled incorrect associations are very difficult to rectify . have you ever seen “ turritella agate” at your favorite fossil dealer’s table ? it has often been polished into cabochons designed to display the whorls of the spiral shaped shell and the agate that has filled the apertures . raw specimens are attractive as well .
the cabachon on the left is 1 . 5” high and is from utah . the raw hand sample on the left is from south central wyoming . both are incorrectly labeled turritella agate in their internet source .
the pieces will probably come with the label “green river formation” and it might be from wyoming , utah or colorado . the location is likely correct , but the fossil identification is not .
have lived since the cretaceous period , thriving during the upper paleocene epoch ( 56 - 60 million years ago ) , just a few million years before “turritella agate” from the green river formation was deposited . however , they were not living in the
this is a fossil turritella mortoni from the paleocene epoch . it was found in the silty shales of the marine aquia formation in king george county , virginia .
the stamps depicted above both correctly depict recent turritella species that are clearly of marine origin . the el salvador stamp issued in 1980 depicts a turritella leucostoma , a species found along the pacific coast from mexico to peru . the 2008 stamp from bosnia and herzegovina features a turritella turris fossil common in the marine miocene rocks of southeast europe .
wonderful article ! we will be linking to this particularly great post on our website . keep up the good writing .
the frequency of turritella agate connects to the base chakra , so that one feels supported , safe , secure and protected in the third dimensional reality , and that one actually creates one’ own reality .
turritella agate can help to opens one’s consciousness so that one is able to connect to the natural spirits of plant and mineral forms and to aid in earth healing .
we have two very comprehensive search facilities , crystals a to z and search for crystals . please explore . . .
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p. tihoni has a body plan that is intermediate to the generalized , fusiform ( torpedo-shaped ) type such as clarias species and the anguilliform ( eel-shaped ) type such as gymnallabes .

this species is known to grow up to 52.8 centimetres ( 20.8 in ) tl .

platyallabes tihoni

platyallabes tihoni is the only species in the genus platyallabes of catfishes of the family clariidae .
platyallabes tihoni is the only species in the genus platyallabes of catfishes ( order siluriformes ) of the family clariidae . this species is found in the malebo pool . p . more
platyallabes tihoni ( poll , 1944 ) - add this species to your
my cats
page . common name ( s ) none type locality kinshasa , zaire . more
food and agriculture organization of the united nations . fishstat . platyallabes tihoni ( dimensionmember ) . ( latest update : 27 nov 2013 ) accessed ( 9 jul 2018 ) . uri : urltoken
clariids , it is not as large as in platyallabes tihoni , where it is one of the diagnostic features for the genus and species ( devaere et al . , 2005a ) . although , figs 3 & 4 show two clear groups , which were tested significantly different , no new species is currently recognized . more
greek , platys = flat + greek , allabes , - etos = a fish of the nile , a kind of lamprey ( ref . 45335 )
africa : lower congo river basin and pool malebo ( stanley - pool ) ( ref . 78218 ) .
maturity : l m ? range ? - ? cm max length : 52 . 8 cm tl male / unsexed ; ( ref . 3820 )
no real information available on the biology of this species . apparently live in crevices between stones and rocks where they burry themselves in the substrate ( ref . 78218 ) .
teugels , g . g . , 1986 . clariidae . p . 66 - 101 . in j . daget , j . - p . gosse and d . f . e . thys van den audenaerde ( eds . ) check - list of the freshwater fishes of africa ( cloffa ) . isnb , brussels , mrac , tervuren ; and orstom , paris . vol . 2 . ( ref . 3820 )
phylogenetic diversity index ( ref . 82805 ) : pd 50 = 1 . 0000 [ uniqueness , from 0 . 5 = low to 2 . 0 = high ] .
bayesian length - weight : a = 0 . 01000 ( 0 . 00244 - 0 . 04107 ) , b = 3 . 04 ( 2 . 81 - 3 . 27 ) , in cm total length , based on all lwr estimates for this body shape ( ref . 93245 ) .
trophic level ( ref . 69278 ) : 3 . 5 ±0 . 5 se ; based on size and trophs of closest relatives
resilience ( ref . 69278 ) : medium , minimum population doubling time 1 . 4 - 4 . 4 years ( preliminary k or fecundity . ) .
vulnerability ( ref . 59153 ) : moderate vulnerability ( 35 of 100 ) .
528mm or 20 . 8
sl . find near , nearer or same sized spp .
unpaired fins continuous , head very broad , paired fins well developed . color is blackish olve - grey , noticeably lighter and sometimes pink on the belly . the caudal fin is light red in color .
in ventral view especially , females are much broader in the body than males of equal age and rearing practices .
revue de zoologie et de botanique africaines v . 38 ( no . 1 ) , p 79 .
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disclaimer : itis taxonomy is based on the latest scientific consensus available , and is provided as a general reference source for interested parties . however , it is not a legal authority for statutory or regulatory purposes . while every effort has been made to provide the most reliable and up - to - date information available , ultimate legal requirements with respect to species are contained in provisions of treaties to which the united states is a party , wildlife statutes , regulations , and any applicable notices that have been published in the federal register . for further information on u . s . legal requirements with respect to protected taxa , please contact the u . s . fish and wildlife service .
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thank you for taking the time to provide feedback on the iucn red list of threatened species website , we are grateful for your input .
brummett , r . , mbe tawe , a . n . , dening touokong , c . , reid , g . m . , snoeks , j . staissny , m . , moelants , t . , mamonekene , v . , ndodet , b . , ifuta , s . n . b . , chilala , a . , monsembula , r . , ibala zamba , a . , opoye itoua , o . , pouomogne , v . , darwall , w . & smith , k .
justification : there are currently no threats to the species known , and it is assessed as least concern . if the construction of inga 3 and grand inga , and the luozi mining project will be executed , the status of this species needs to be reassessed .
there are currently no threats to the species known . inga 1 and 2 are existing dams with a minimal impact . the possible future elaboration of the dam complex with inga 3 and later possibly grand inga will pose a great threat to the species that has a limited distribution to this region . given the restricted mainstream habitat and mainstream impacts such as pollution , it can be threatened in the future by mining in the luozi region . the key component of concrete is found in this region , and there is potential for mining in the area .
to make use of this information , please check the < terms of use > .
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the urltoken website brings together statistics , maps , pictures , and documents on food and agriculture from throughout the fao organization in one convenient location . this means that instead of searching multiple sites and sources , you will be able to go to one central place in order to collect or view the data that interests you . to assist in data retrieval , the site provides an efficient search engine as well as easy - to - use navigation menus .
heads up ! we will have a convenient download format available for this resource soon .
food and agriculture organization of the united nations . ( 2012 ) . fishstat . rome , italy : fao .
food and agriculture organization of the united nations . 2012 . fishstat . rome , italy : fao .
food and agriculture organization of the united nations . ( 2012 ) . fishstat . rome , italy , fao .