Annelid

qas: question: What kind of symmetry do annelids have?
answers: text: bilateral

question: What do annelids use to move?
answers: text: parapodia

question: Which subtype of annelids includes most marine worms?
answers: text: polychaetes

question: Which subtype of annelids includes earthworms?
answers: text: oligochaetes

question: Since 1997, what are leeches seen as a subgroup of?
answers: text: oligochaetes

question: What kind of symmetry do annelids lack?

question: What do annelids use to fly?

question: Which subtype of annelids includes most space worms?

question: Which subtype of annelids includes marsworms?

question: What are leeches seen as a subgroup of since 1897?
context: The annelids are bilaterally symmetrical, triploblastic, coelomate, invertebrate organisms. They also have parapodia for locomotion. Most textbooks still use the traditional division into polychaetes (almost all marine), oligochaetes (which include earthworms) and leech-like species. Cladistic research since 1997 has radically changed this scheme, viewing leeches as a sub-group of oligochaetes and oligochaetes as a sub-group of polychaetes. In addition, the Pogonophora, Echiura and Sipuncula, previously regarded as separate phyla, are now regarded as sub-groups of polychaetes. Annelids are considered members of the Lophotrochozoa, a "super-phylum" of protostomes that also includes molluscs, brachiopods, flatworms and nemerteans.

qas: question: What separates many annelids' segments?
answers: text: Septa

question: Which annelids show no segmentation?
answers: text: Echiura and Sipuncula

question: What end of annelids with well-developed segmentation has muscles that act like hearts?
answers: text: front

question: What is movement by ripples called?
answers: text: peristalsis

question: What movement method do some burrowing annelids use?
answers: text: turn their pharynges inside out to drag themselves

question: What integrates many annelids' segments?

question: Which annelids show only segmentation?

question: What end of annelids with well-developed segmentation have muscles that act like brains?

question: What is movement by ripples no longer called?

question: What movement method do some extinct annelids use?
context: The basic annelid form consists of multiple segments. Each segment has the same sets of organs and, in most polychaetes, has a pair of parapodia that many species use for locomotion. Septa separate the segments of many species, but are poorly defined or absent in others, and Echiura and Sipuncula show no obvious signs of segmentation. In species with well-developed septa, the blood circulates entirely within blood vessels, and the vessels in segments near the front ends of these species are often built up with muscles that act as hearts. The septa of such species also enable them to change the shapes of individual segments, which facilitates movement by peristalsis ("ripples" that pass along the body) or by undulations that improve the effectiveness of the parapodia. In species with incomplete septa or none, the blood circulates through the main body cavity without any kind of pump, and there is a wide range of locomotory techniques – some burrowing species turn their pharynges inside out to drag themselves through the sediment.

qas: question: How do annelids normally reproduce?
answers: text: sexual reproduction

question: What can asexual reproduction techniques help annelids do?
answers: text: regenerate after severe injuries

question: What larvae live like plankton?
answers: text: trochophore

question: What annelids are hermaphrodites?
answers: text: Oligochaetes

question: What annelids make a cocoon in a ring around themselves?
answers: text: Oligochaetes

question: How do annelids never reproduce?

question: What can asexual reproduction techniques prevent annelids from doing?

question: What larvae live like whales?

question: What annelids dislike hermaphrodites?

question: What annelids make a cocoon in a pyramid around themselves?
context: Although many species can reproduce asexually and use similar mechanisms to regenerate after severe injuries, sexual reproduction is the normal method in species whose reproduction has been studied. The minority of living polychaetes whose reproduction and lifecycles are known produce trochophore larvae, that live as plankton and then sink and metamorphose into miniature adults. Oligochaetes are full hermaphrodites and produce a ring-like cocoon around their bodies, in which the eggs and hatchlings are nourished until they are ready to emerge.

qas: question: How do earthworms help the soil they live in?
answers: text: aeration and enriching

question: How much of near-shore marine annelids are burrowing?
answers: text: up to a third

question: How do burrowing marine annelids help ocean ecosystems?
answers: text: enabling water and oxygen to penetrate the sea floor

question: What annelids' jaws are being studied by engineers?
answers: text: Ragworms

question: Why are some leeches endangered?
answers: text: they have been over-harvested

question: How do earthworms ruin the soil they live in?

question: How much of near-shore aerial annelids are burrowing?

question: How do burrowing marine annelids remove ocean ecosystems?

question: What annelids' ears are being studied by engineers?

question: Why are no leeches endangered?
context: Earthworms are Oligochaetes that support terrestrial food chains both as prey and in some regions are important in aeration and enriching of soil. The burrowing of marine polychaetes, which may constitute up to a third of all species in near-shore environments, encourages the development of ecosystems by enabling water and oxygen to penetrate the sea floor. In addition to improving soil fertility, annelids serve humans as food and as bait. Scientists observe annelids to monitor the quality of marine and fresh water. Although blood-letting is no longer in favor with doctors, some leech species are regarded as endangered species because they have been over-harvested for this purpose in the last few centuries. Ragworms' jaws are now being studied by engineers as they offer an exceptional combination of lightness and strength.

qas: question: Why are annelid fossils rare?
answers: text: annelids are soft-bodied

question: What fossil signs of annelids are found?
answers: text: jaws and the mineralized tubes that some of the species secreted

question: How old is the earliest annelid fossil?
answers: text: 518 million years ago

question: What types of annelids appeared 299 million years ago?
answers: text: modern mobile polychaete groups

question: What period started around 472 million years ago?
answers: text: the mid Ordovician

question: Why are annelid fossils common?

question: What fossil signs of annelids can no longer be found?

question: How old is the oldest living annelid?

question: What types of annelids disappeared 299 million years ago?

question: What period started around 372 million years ago?
context: Since annelids are soft-bodied, their fossils are rare – mostly jaws and the mineralized tubes that some of the species secreted. Although some late Ediacaran fossils may represent annelids, the oldest known fossil that is identified with confidence comes from about 518 million years ago in the early Cambrian period. Fossils of most modern mobile polychaete groups appeared by the end of the Carboniferous, about 299 million years ago. Palaeontologists disagree about whether some body fossils from the mid Ordovician, about 472 to 461 million years ago, are the remains of oligochaetes, and the earliest indisputable fossils of the group appear in the Tertiary period, which began 65 million years ago.

qas: question: What externally divides annelids' segments?
answers: text: shallow ring-like constrictions called annuli

question: What divides annelids' segments internally?
answers: text: septa ("partitions")

question: What do the segments of an annelid share?
answers: text: a common gut, circulatory system and nervous system

question: What covers an annelid's exterior?
answers: text: a cuticle

question: What is an annelid's cuticle made of?
answers: text: collagen

question: What externally combines annelids' segments?

question: What combines annelids' segments internally?

question: What do the segments of an annelid lack?

question: What conceals an annelid's exterior?

question: What is an annelid's cuticle made into?
context: No single feature distinguishes Annelids from other invertebrate phyla, but they have a distinctive combination of features. Their bodies are long, with segments that are divided externally by shallow ring-like constrictions called annuli and internally by septa ("partitions") at the same points, although in some species the septa are incomplete and in a few cases missing. Most of the segments contain the same sets of organs, although sharing a common gut, circulatory system and nervous system makes them inter-dependent. Their bodies are covered by a cuticle (outer covering) that does not contain cells but is secreted by cells in the skin underneath, is made of tough but flexible collagen and does not molt – on the other hand arthropods' cuticles are made of the more rigid α-chitin, and molt until the arthropods reach their full size. Most annelids have closed circulatory systems, where the blood makes its entire circuit via blood vessels.

qas: question: What language does the term 'chaetae' come from?
answers: text: Greek

question: What does 'chaetae' mean?
answers: text: hair

question: Which parts of annelids are different from true segments?
answers: text: the frontmost and rearmost sections

question: What language does 'prostomium' come from?
answers: text: Greek

question: What does 'pygidium' mean?
answers: text: little tail

question: What language is the term 'chaetae' banned in?

question: What does 'chaetae' no longer mean?

question: Which parts of annelids are different from fake segments?

question: What kind of annelid has four true segments?
context: Most of an annelid's body consists of segments that are practically identical, having the same sets of internal organs and external chaetae (Greek χαιτη, meaning "hair") and, in some species, appendages. However, the frontmost and rearmost sections are not regarded as true segments as they do not contain the standard sets of organs and do not develop in the same way as the true segments. The frontmost section, called the prostomium (Greek προ- meaning "in front of" and στομα meaning "mouth") contains the brain and sense organs, while the rearmost, called the pygidium (Greek πυγιδιον, meaning "little tail") or periproct contains the anus, generally on the underside. The first section behind the prostomium, called the peristomium (Greek περι- meaning "around" and στομα meaning "mouth"), is regarded by some zoologists as not a true segment, but in some polychaetes the peristomium has chetae and appendages like those of other segments.

qas: question: How are the layers arranged in annelids' cuticles?
answers: text: spiral in alternating directions

question: What are annelids' cuticles made out of?
answers: text: collagen fibers

question: What do non-cuticle annelids use to protect their skin?
answers: text: mucus-secreting glands in the epidermis

question: What layer is under the epidermis?
answers: text: the dermis

question: What does 'coelom' mean?
answers: text: (body cavity

question: How are the eyes arranged in annelids' cuticles?

question: What are annelids' brain made out of?

question: What do non-cuticle annelids use to protect their offspring?

question: What annelid is under the epidermis?
context: Annelids' cuticles are made of collagen fibers, usually in layers that spiral in alternating directions so that the fibers cross each other. These are secreted by the one-cell deep epidermis (outermost skin layer). A few marine annelids that live in tubes lack cuticles, but their tubes have a similar structure, and mucus-secreting glands in the epidermis protect their skins. Under the epidermis is the dermis, which is made of connective tissue, in other words a combination of cells and non-cellular materials such as collagen. Below this are two layers of muscles, which develop from the lining of the coelom (body cavity): circular muscles make a segment longer and slimmer when they contract, while under them are longitudinal muscles, usually four distinct strips, whose contractions make the segment shorter and fatter. Some annelids also have oblique internal muscles that connect the underside of the body to each side.

qas: question: What do chetoblast cells do?
answers: text: hair-forming

question: What hair-like extensions do chetoblasts make?
answers: text: microvilli

question: What are setae?
answers: text: bristles

question: What are parapodia against?

question: What do chetoblast cells destroy?

question: What hair-like extensions do chetoblasts eat?

question: What are setae never considered?
context: The setae ("hairs") of annelids project out from the epidermis to provide traction and other capabilities. The simplest are unjointed and form paired bundles near the top and bottom of each side of each segment. The parapodia ("limbs") of annelids that have them often bear more complex chetae at their tips – for example jointed, comb-like or hooked. Chetae are made of moderately flexible β-chitin and are formed by follicles, each of which has a chetoblast ("hair-forming") cell at the bottom and muscles that can extend or retract the cheta. The chetoblasts produce chetae by forming microvilli, fine hair-like extensions that increase the area available for secreting the cheta. When the cheta is complete, the microvilli withdraw into the chetoblast, leaving parallel tunnels that run almost the full length of the cheta. Hence annelids' chetae are structurally different from the setae ("bristles") of arthropods, which are made of the more rigid α-chitin, have a single internal cavity, and are mounted on flexible joints in shallow pits in the cuticle.

qas: question: What are cirri?
answers: text: fused bundles of cilia

question: What kind of parapodia do burrowing annelids often have?
answers: text: ridges whose tips bear hooked chetae

question: What type of annelids have limb-like parapodia?
answers: text: polychaetes

question: What are parapodia?
answers: text: unjointed paired extensions of the body wall

question: Where are cirri never found?

question: What kind of parapodia do aerial annelids often have?

question: What type of annelids have dream-like parapodia?

question: What are parapodia no longer considered?
context: Nearly all polychaetes have parapodia that function as limbs, while other major annelid groups lack them. Parapodia are unjointed paired extensions of the body wall, and their muscles are derived from the circular muscles of the body. They are often supported internally by one or more large, thick chetae. The parapodia of burrowing and tube-dwelling polychaetes are often just ridges whose tips bear hooked chetae. In active crawlers and swimmers the parapodia are often divided into large upper and lower paddles on a very short trunk, and the paddles are generally fringed with chetae and sometimes with cirri (fused bundles of cilia) and gills.

qas: question: What are ganglia?
answers: text: local control centers

question: What is an annelid's brain in a ring around?
answers: text: the pharynx

question: What is a pharynx?
answers: text: throat

question: Where are clitellates' brains?
answers: text: in the peristomium or sometimes the first segment behind the peristomium

question: Where are polychaetes' brains?
answers: text: in the prostomium

question: What is an annelid's brain in a sphere around?

question: Where are clitellates' teeth?

question: Where are polychaetes' bodies?

question: What is rarely "ladder-like"?

question: What nerve cords are never fused in polychaetes?
context: The brain generally forms a ring round the pharynx (throat), consisting of a pair of ganglia (local control centers) above and in front of the pharynx, linked by nerve cords either side of the pharynx to another pair of ganglia just below and behind it. The brains of polychaetes are generally in the prostomium, while those of clitellates are in the peristomium or sometimes the first segment behind the peristomium. In some very mobile and active polychaetes the brain is enlarged and more complex, with visible hindbrain, midbrain and forebrain sections. The rest of the central nervous system is generally "ladder-like", consisting of a pair of nerve cords that run through the bottom part of the body and have in each segment paired ganglia linked by a transverse connection. From each segmental ganglion a branching system of local nerves runs into the body wall and then encircles the body. However, in most polychaetes the two main nerve cords are fused, and in the tube-dwelling genus Owenia the single nerve chord has no ganglia and is located in the epidermis.

qas: question: What species group are annelids' muscle control similar to?
answers: text: arthropods

question: What are giant axons?
answers: text: the output signal lines of nerve cells

question: How do annelids withdraw from danger?
answers: text: shortening their bodies

question: What species group are annelids' mind control similar to?

question: What do giant axons destroy?

question: How do annelids increase danger?

question: What worms are very slow to retreat from danger?
context: As in arthropods, each muscle fiber (cell) is controlled by more than one neuron, and the speed and power of the fiber's contractions depends on the combined effects of all its neurons. Vertebrates have a different system, in which one neuron controls a group of muscle fibers. Most annelids' longitudinal nerve trunks include giant axons (the output signal lines of nerve cells). Their large diameter decreases their resistance, which allows them to transmit signals exceptionally fast. This enables these worms to withdraw rapidly from danger by shortening their bodies. Experiments have shown that cutting the giant axons prevents this escape response but does not affect normal movement.

qas: question: What kind of things can annelids' sensors detect?
answers: text: light, chemicals, pressure waves and contact

question: What does 'nuchal' mean?
answers: text: on the neck

question: What type of annelids have nuchal organs?
answers: text: polychaetes

question: What are the nuchal organs thought to do?
answers: text: chemosensors

question: What term means 'little eyes'?
answers: text: ocelli

question: What kind of things can annelids' sensors remove?

question: What type of annelids have human organs?

question: What are nuchal organs thought to kill?

question: What term means 'massive eyes'?
context: The sensors are primarily single cells that detect light, chemicals, pressure waves and contact, and are present on the head, appendages (if any) and other parts of the body. Nuchal ("on the neck") organs are paired, ciliated structures found only in polychaetes, and are thought to be chemosensors. Some polychaetes also have various combinations of ocelli ("little eyes") that detect the direction from which light is coming and camera eyes or compound eyes that can probably form images. The compound eyes probably evolved independently of arthropods' eyes. Some tube-worms use ocelli widely spread over their bodies to detect the shadows of fish, so that they can quickly withdraw into their tubes. Some burrowing and tube-dwelling polychaetes have statocysts (tilt and balance sensors) that tell them which way is down. A few polychaete genera have on the undersides of their heads palps that are used both in feeding and as "feelers", and some of these also have antennae that are structurally similar but probably are used mainly as "feelers".

qas: question: What are coelomata?
answers: text: body cavities

question: What are annelids' body cavities separated from other segments by?
answers: text: septa

question: What are annelids' body cavities separated from each other by?
answers: text: vertical mesenteries

question: What is the mesothelium made of?
answers: text: modified epitheliomuscular cells

question: What are coelomata removed from?

question: What are annelids' body cavities combined with other segments by?

question: What are annelids' body cavities separated from eyes by?

question: What is the mesothelium never made of?
context: Most annelids have a pair of coelomata (body cavities) in each segment, separated from other segments by septa and from each other by vertical mesenteries. Each septum forms a sandwich with connective tissue in the middle and mesothelium (membrane that serves as a lining) from the preceding and following segments on either side. Each mesentery is similar except that the mesothelium is the lining of each of the pair of coelomata, and the blood vessels and, in polychaetes, the main nerve cords are embedded in it. The mesothelium is made of modified epitheliomuscular cells; in other words, their bodies form part of the epithelium but their bases extend to form muscle fibers in the body wall. The mesothelium may also form radial and circular muscles on the septa, and circular muscles around the blood vessels and gut. Parts of the mesothelium, especially on the outside of the gut, may also form chloragogen cells that perform similar functions to the livers of vertebrates: producing and storing glycogen and fat; producing the oxygen-carrier hemoglobin; breaking down proteins; and turning nitrogenous waste products into ammonia and urea to be excreted.

qas: question: How does peristalsis work?
answers: text: waves of contraction and expansion that sweep along the body

question: Why are annelids' segments like water-balloons?
answers: text: the septa enable the circular and longitudinal muscles to change the shape of individual segments

question: What are phrynges?
answers: text: throats

question: What are cilia?
answers: text: fine muscle-powered hairs

question: How does peristalsis stop working?

question: Why are annelids' segments like helium-balloons?

question: What are often complete in annelids?

question: What do not have throats?
context: Many annelids move by peristalsis (waves of contraction and expansion that sweep along the body), or flex the body while using parapodia to crawl or swim. In these animals the septa enable the circular and longitudinal muscles to change the shape of individual segments, by making each segment a separate fluid-filled "balloon". However, the septa are often incomplete in annelids that are semi-sessile or that do not move by peristalsis or by movements of parapodia – for example some move by whipping movements of the body, some small marine species move by means of cilia (fine muscle-powered hairs) and some burrowers turn their pharynges (throats) inside out to penetrate the sea-floor and drag themselves into it.

qas: question: What can coelomocyte cells defend against?
answers: text: parasites and infections

question: What type of pigment is dissolved in annelids' blood?
answers: text: Respiratory

question: What runs the length of annelids' bodies with well-developed septa?
answers: text: blood vessels

question: What do annelids without septa have to use for circulation?
answers: text: circulation within the coelom

question: What can coelomocyte cells heal?

question: What type of pigment is created in annelids' blood?

question: What runs the length of annelids' brains with well-developed septa?

question: What do annelids with septa have to use for blood?
context: The fluid in the coelomata contains coelomocyte cells that defend the animals against parasites and infections. In some species coelomocytes may also contain a respiratory pigment – red hemoglobin in some species, green chlorocruorin in others (dissolved in the plasma) – and provide oxygen transport within their segments. Respiratory pigment is also dissolved in the blood plasma. Species with well-developed septa generally also have blood vessels running all long their bodies above and below the gut, the upper one carrying blood forwards while the lower one carries it backwards. Networks of capillaries in the body wall and around the gut transfer blood between the main blood vessels and to parts of the segment that need oxygen and nutrients. Both of the major vessels, especially the upper one, can pump blood by contracting. In some annelids the forward end of the upper blood vessel is enlarged with muscles to form a heart, while in the forward ends of many earthworms some of the vessels that connect the upper and lower main vessels function as hearts. Species with poorly developed or no septa generally have no blood vessels and rely on the circulation within the coelom for delivering nutrients and oxygen.

qas: question: What type of annelids are very different from others?
answers: text: leeches and their closest relatives

question: What type of tissue takes up most of the body of a leech?
answers: text: connective tissue layer of the body wall

question: How many coelomata do leeches have?
answers: text: two

question: What lines the coelomata of leeches?
answers: text: mesothelium

question: What do leeches use to move?
answers: text: suckers at their front and rear ends

question: What type of annelids are very identical to others?

question: What type of tissue eats most of the body of a leech?

question: How many brains do leeches have?

question: What lines the bones of leeches?

question: What do leeches use to fly?
context: However, leeches and their closest relatives have a body structure that is very uniform within the group but significantly different from that of other annelids, including other members of the Clitellata. In leeches there are no septa, the connective tissue layer of the body wall is so thick that it occupies much of the body, and the two coelomata are widely separated and run the length of the body. They function as the main blood vessels, although they are side-by-side rather than upper and lower. However, they are lined with mesothelium, like the coelomata and unlike the blood vessels of other annelids. Leeches generally use suckers at their front and rear ends to move like inchworms. The anus is on the upper surface of the pygidium.

qas: question: What does 'everted' mean?
answers: text: turned inside out to extend

question: What part of a polychaete can be everted?
answers: text: pharynx

question: What types of annelids have evolved jaws?
answers: text: Eunicidae and Phyllodocidae

question: What do annelids use jaws for?
answers: text: seizing prey, biting off pieces of vegetation, or grasping dead and decaying matter

question: What do some annelids have 'crowns' of?
answers: text: palps covered in cilia

question: What part of a polychaete can be inverted?

question: What types of annelids are missing jaws?

question: What do annelids use robots for?

question: What do some annelids have 'trophies' of?
context: Feeding structures in the mouth region vary widely, and have little correlation with the animals' diets. Many polychaetes have a muscular pharynx that can be everted (turned inside out to extend it). In these animals the foremost few segments often lack septa so that, when the muscles in these segments contract, the sharp increase in fluid pressure from all these segments everts the pharynx very quickly. Two families, the Eunicidae and Phyllodocidae, have evolved jaws, which can be used for seizing prey, biting off pieces of vegetation, or grasping dead and decaying matter. On the other hand, some predatory polychaetes have neither jaws nor eversible pharynges. Selective deposit feeders generally live in tubes on the sea-floor and use palps to find food particles in the sediment and then wipe them into their mouths. Filter feeders use "crowns" of palps covered in cilia that wash food particles towards their mouths. Non-selective deposit feeders ingest soil or marine sediments via mouths that are generally unspecialized. Some clitellates have sticky pads in the roofs of their mouths, and some of these can evert the pads to capture prey. Leeches often have an eversible proboscis, or a muscular pharynx with two or three teeth.

qas: question: What type of annelids are tube-dwelling?
answers: text: Siboglinidae

question: What blocks the Siboglinidae's gut?
answers: text: a swollen lining

question: How much of a Siboglinidae's weight is symbiotic bacteria?
answers: text: 15%

question: What gases come from hydrothermal vents?
answers: text: hydrogen sulfide and carbon dioxide

question: What gases come from seeps?
answers: text: methane

question: What type of annelids are brain-dwelling?

question: What blocks the Siboglinidae's blood?

question: How much of a Siboglinidae's consciousness is symbiotic bacteria?

question: What liquids come from hydrothermal bottles?

question: What foods come from seeps?
context: The gut is generally an almost straight tube supported by the mesenteries (vertical partitions within segments), and ends with the anus on the underside of the pygidium. However, in members of the tube-dwelling family Siboglinidae the gut is blocked by a swollen lining that houses symbiotic bacteria, which can make up 15% of the worms' total weight. The bacteria convert inorganic matter – such as hydrogen sulfide and carbon dioxide from hydrothermal vents, or methane from seeps – to organic matter that feeds themselves and their hosts, while the worms extend their palps into the gas flows to absorb the gases needed by the bacteria.

qas: question: What do metanephridia remove?
answers: text: soluble waste products

question: What do annelids without blood vessels do to remove waste?
answers: text: protonephridia

question: How many stages are there in annelids' waste filtration?
answers: text: two

question: What annelid system combines both filtration states in one organ?
answers: text: protonephridia

question: What do metanephridia produce?

question: What do annelids without blood vessels do to increase waste?

question: How many stages are there in annelids' water filtration?

question: What annelid system combines both filtration states in eight organs?
context: Annelids with blood vessels use metanephridia to remove soluble waste products, while those without use protonephridia. Both of these systems use a two-stage filtration process, in which fluid and waste products are first extracted and these are filtered again to re-absorb any re-usable materials while dumping toxic and spent materials as urine. The difference is that protonephridia combine both filtration stages in the same organ, while metanephridia perform only the second filtration and rely on other mechanisms for the first – in annelids special filter cells in the walls of the blood vessels let fluids and other small molecules pass into the coelomic fluid, where it circulates to the metanephridia. In annelids the points at which fluid enters the protonephridia or metanephridia are on the forward side of a septum while the second-stage filter and the nephridiopore (exit opening in the body wall) are in the following segment. As a result, the hindmost segment (before the growth zone and pygidium) has no structure that extracts its wastes, as there is no following segment to filter and discharge them, while the first segment contains an extraction structure that passes wastes to the second, but does not contain the structures that re-filter and discharge urine.

qas: question: How many sexes of annelids were there originally?
answers: text: two

question: What releases sperm from annelids?
answers: text: nephridia

question: What do annelid eggs become?
answers: text: trochophore larvae

question: What do annelids' larvae live like?
answers: text: plankton

question: What does the trochophore become when annelids mature?
answers: text: the prostomium (head)

question: What releases sperm from annelids eyes?

question: What do annelid eggs explode inside?

question: What do annelids' larvae like to eat?

question: What does the trochophore become when annelids die?
context: It is thought that annelids were originally animals with two separate sexes, which released ova and sperm into the water via their nephridia. The fertilized eggs develop into trochophore larvae, which live as plankton. Later they sink to the sea-floor and metamorphose into miniature adults: the part of the trochophore between the apical tuft and the prototroch becomes the prostomium (head); a small area round the trochophore's anus becomes the pygidium (tail-piece); a narrow band immediately in front of that becomes the growth zone that produces new segments; and the rest of the trochophore becomes the peristomium (the segment that contains the mouth).

qas: question: How many species of polychaetes have known lifecycles?
answers: text: about 25%

question: What percent of polychaetes produce yolk-rich eggs?
answers: text: 14%

question: What is the benefit of yolk-rich eggs?
answers: text: reduce the time the larva needs to spend among the plankton

question: What are most polychaetes' eggs covered in?
answers: text: jelly

question: How many species of polychaetes have impossible lifecycles?

question: What percent of polychaetes produce milk?

question: What is the benefit of rotten eggs?

question: What are all polychaetes' eggs covered in?
context: However, the lifecycles of most living polychaetes, which are almost all marine animals, are unknown, and only about 25% of the 300+ species whose lifecycles are known follow this pattern. About 14% use a similar external fertilization but produce yolk-rich eggs, which reduce the time the larva needs to spend among the plankton, or eggs from which miniature adults emerge rather than larvae. The rest care for the fertilized eggs until they hatch – some by producing jelly-covered masses of eggs which they tend, some by attaching the eggs to their bodies and a few species by keeping the eggs within their bodies until they hatch. These species use a variety of methods for sperm transfer; for example, in some the females collect sperm released into the water, while in others the males have a penis that inject sperm into the female. There is no guarantee that this is a representative sample of polychaetes' reproductive patterns, and it simply reflects scientists' current knowledge.

qas: question: What do some non-single-sex polychaetes do?
answers: text: change sex

question: What are most polychaetes lacking for reproduction?
answers: text: permanent gonads

question: How do some annelids get a one-time chance at a better spawning spot?
answers: text: the rear of the body splits off and becomes a separate individual

question: What do all non-single-sex polychaetes do?

question: What are no polychaetes lacking for reproduction?

question: How do some annelids get a three-time chance at a better spawning spot?

question: How many polychaetes breed an infinite amount of times?
context: Some polychaetes breed only once in their lives, while others breed almost continuously or through several breeding seasons. While most polychaetes remain of one sex all their lives, a significant percentage of species are full hermaphrodites or change sex during their lives. Most polychaetes whose reproduction has been studied lack permanent gonads, and it is uncertain how they produce ova and sperm. In a few species the rear of the body splits off and becomes a separate individual that lives just long enough to swim to a suitable environment, usually near the surface, and spawn.

qas: question: What annelid group includes leeches and earthworms?
answers: text: clitellates

question: What type of sex are most earthworms?
answers: text: hermaphrodites

question: Where are leeches' eggs fertilized?
answers: text: in the ovaries

question: Where do leeches move their eggs to?
answers: text: the cocoon

question: What type of annelids hatch as miniature adults?
answers: text: clitellates

question: What annelid group dislikes leeches and earthworms?

question: What type of creature are most earthworms?

question: Where are leeches' gardens fertilized?

question: Where do leeches eat their eggs?

question: What type of annelids hatch as giant adults?
context: Most mature clitellates (the group that includes earthworms and leeches) are full hermaphrodites, although in a few leech species younger adults function as males and become female at maturity. All have well-developed gonads, and all copulate. Earthworms store their partners' sperm in spermathecae ("sperm stores") and then the clitellum produces a cocoon that collects ova from the ovaries and then sperm from the spermathecae. Fertilization and development of earthworm eggs takes place in the cocoon. Leeches' eggs are fertilized in the ovaries, and then transferred to the cocoon. In all clitellates the cocoon also either produces yolk when the eggs are fertilized or nutrients while they are developing. All clitellates hatch as miniature adults rather than larvae.

qas: question: Who published a book about worms in 1881?
answers: text: Charles Darwin

question: What was the first scientific study of how earthworms help soil?
answers: text: The Formation of Vegetable Mould through the Action of Worms

question: Where do earthworms prefer to live on the surface?
answers: text: generally in moist leaf litter

question: How does burrowers' loosening help the soil?
answers: text: oxygen and water can penetrate it

question: What is the largest bird that eats earthworms?
answers: text: storks

question: Who published a book about worms in 1781?

question: What was the only scientific study of how earthworms help soil?

question: Where do earthworms prefer to live in space?

question: How does burrowers' tightening help the soil?

question: What is the only bird that can eat earthworms?
context: Charles Darwin's book The Formation of Vegetable Mould through the Action of Worms (1881) presented the first scientific analysis of earthworms' contributions to soil fertility. Some burrow while others live entirely on the surface, generally in moist leaf litter. The burrowers loosen the soil so that oxygen and water can penetrate it, and both surface and burrowing worms help to produce soil by mixing organic and mineral matter, by accelerating the decomposition of organic matter and thus making it more quickly available to other organisms, and by concentrating minerals and converting them to forms that plants can use more easily. Earthworms are also important prey for birds ranging in size from robins to storks, and for mammals ranging from shrews to badgers, and in some cases conserving earthworms may be essential for conserving endangered birds.

qas: question: Where were native earthworms killed by glaciers?
answers: text: glaciated areas of North America

question: Where did most of the current earthworms in glacial areas come from?
answers: text: Europe

question: What type of forests can be hurt by invasive worms?
answers: text: Northern hardwood forests

question: Where were asian earthworms killed by glaciers?

question: Where did all of the current earthworms in glacial areas come from?

question: What type of forests are immune to invasive worms?

question: What are no longer considered an invasive species?
context: Terrestrial annelids can be invasive in some situations. In the glaciated areas of North America, for example, almost all native earthworms are thought to have been killed by the glaciers and the worms currently found in those areas are all introduced from other areas, primarily from Europe, and, more recently, from Asia. Northern hardwood forests are especially negatively impacted by invasive worms through the loss of leaf duff, soil fertility, changes in soil chemistry and the loss of ecological diversity. Especially of concern is Amynthas agrestis and at least one state (Wisconsin) has listed it as a prohibited species.

qas: question: What type of annelid tunnels through coral?
answers: text: Palolo worm

question: What annelid's rear end do Samoans like to eat?
answers: text: Palolo worm

question: What type of bait do experienced anglers prefer?
answers: text: spawning modules

question: What do some polychaetes eat that has been causing problems?
answers: text: molluscs

question: What type of worm have there been proposals to farm?
answers: text: Ragworms

question: What type of annelid tunnels through gold?

question: What annelid's rear end do Samoans like to drink?

question: What type of bait do experienced anglers dislike?

question: What do some polychaetes eat that is harmless?

question: What type of worm have there been proposals to kill?
context: Earthworms make a significant contribution to soil fertility. The rear end of the Palolo worm, a marine polychaete that tunnels through coral, detaches in order to spawn at the surface, and the people of Samoa regard these spawning modules as a delicacy. Anglers sometimes find that worms are more effective bait than artificial flies, and worms can be kept for several days in a tin lined with damp moss. Ragworms are commercially important as bait and as food sources for aquaculture, and there have been proposals to farm them in order to reduce over-fishing of their natural populations. Some marine polychaetes' predation on molluscs causes serious losses to fishery and aquaculture operations.

qas: question: When did leeches begin being used for blood-letting?
answers: text: 30 AD

question: Where did leeches begin being used for blood-letting?
answers: text: China

question: When did Rome begin using leeches?
answers: text: 50 AD

question: When did India begin using leeches?
answers: text: 200 AD

question: Which organizations list Hirudo medicinalis as endangered?
answers: text: IUCN and CITES

question: Where did leeches begin being used for blood transfusions?

question: When did Russia begin using leeches?

question: Which organizations list Hirudo medicinalis as extinct?

question: When did India stop using leeches?
context: Accounts of the use of leeches for the medically dubious practise of blood-letting have come from China around 30 AD, India around 200 AD, ancient Rome around 50 AD and later throughout Europe. In the 19th century medical demand for leeches was so high that some areas' stocks were exhausted and other regions imposed restrictions or bans on exports, and Hirudo medicinalis is treated as an endangered species by both IUCN and CITES. More recently leeches have been used to assist in microsurgery, and their saliva has provided anti-inflammatory compounds and several important anticoagulants, one of which also prevents tumors from spreading.

qas: question: When did Cloudina exist?
answers: text: 549 to 542 million years ago

question: What do some people think Cloudina should be called instead of an annelid?
answers: text: cnidarian

question: How old were the fossils of Canadia and Burgessochaeta found in Canada?
answers: text: 505 million years

question: What era was underway 505 million years ago?
answers: text: early Cambrian

question: Where was Myoscolex found?
answers: text: Australia

question: When did Cloudina disappear?

question: What do all people think Cloudina should be called instead of an annelid?

question: How old were the fossils of Canadia and Burgessochaeta found in Australia?

question: Where was Myoscolex unknown?
context: Since annelids are soft-bodied, their fossils are rare. Polychaetes' fossil record consists mainly of the jaws that some species had and the mineralized tubes that some secreted. Some Ediacaran fossils such as Dickinsonia in some ways resemble polychaetes, but the similarities are too vague for these fossils to be classified with confidence. The small shelly fossil Cloudina, from 549 to 542 million years ago, has been classified by some authors as an annelid, but by others as a cnidarian (i.e. in the phylum to which jellyfish and sea anemones belong). Until 2008 the earliest fossils widely accepted as annelids were the polychaetes Canadia and Burgessochaeta, both from Canada's Burgess Shale, formed about 505 million years ago in the early Cambrian. Myoscolex, found in Australia and a little older than the Burgess Shale, was possibly an annelid. However, it lacks some typical annelid features and has features which are not usually found in annelids and some of which are associated with other phyla. Then Simon Conway Morris and John Peel reported Phragmochaeta from Sirius Passet, about 518 million years old, and concluded that it was the oldest annelid known to date. There has been vigorous debate about whether the Burgess Shale fossil Wiwaxia was a mollusc or an annelid. Polychaetes diversified in the early Ordovician, about 488 to 474 million years ago. It is not until the early Ordovician that the first annelid jaws are found, thus the crown-group cannot have appeared before this date and probably appeared somewhat later. By the end of the Carboniferous, about 299 million years ago, fossils of most of the modern mobile polychaete groups had appeared. Many fossil tubes look like those made by modern sessile polychaetes  , but the first tubes clearly produced by polychaetes date from the Jurassic, less than 199 million years ago.

qas: question: When did the Tertiary period begin?
answers: text: 65 million years ago

question: What era did oligochaetes evolve in?
answers: text: early Cretaceous

question: What type of annelid fossils have been found from the mid Ordovician period?
answers: text: oligochaetes

question: When were the earliest annelid fossils found?
answers: text: 472 to 461 million years ago

question: When did the Tertiary period stop existing?

question: What era did oligochaetes devolve in?

question: What type of annelid fossils have been lost during the mid Ordovician period?

question: When were the only annelid fossils found?
context: The earliest good evidence for oligochaetes occurs in the Tertiary period, which began 65 million years ago, and it has been suggested that these animals evolved around the same time as flowering plants in the early Cretaceous, from 130 to 90 million years ago. A trace fossil consisting of a convoluted burrow partly filled with small fecal pellets may be evidence that earthworms were present in the early Triassic period from 251 to 245 million years ago. Body fossils going back to the mid Ordovician, from 472 to 461 million years ago, have been tentatively classified as oligochaetes, but these identifications are uncertain and some have been disputed.

qas: question: What two groups are annelids traditionally divided among?
answers: text: polychaetes and clitellates

question: What subtype of clitellates contains earthworms?
answers: text: oligochaetes

question: What subtype of clitellates contains leeches?
answers: text: hirudinomorphs

question: How many polychaete families are there?
answers: text: approximately 80

question: When did Greg Rouse begin trying to categorize polychaetes?
answers: text: 1997

question: What three groups are annelids traditionally divided among?

question: What subtype of clitellates contains spaceworms?

question: What subtype of clitellates contains lemurs?

question: How many polychaete political parties are there?

question: When did Greg Rouse begin trying to categorize planets?
context: Traditionally the annelids have been divided into two major groups, the polychaetes and clitellates. In turn the clitellates were divided into oligochaetes, which include earthworms, and hirudinomorphs, whose best-known members are leeches. For many years there was no clear arrangement of the approximately 80 polychaete families into higher-level groups. In 1997 Greg Rouse and Kristian Fauchald attempted a "first heuristic step in terms of bringing polychaete systematics to an acceptable level of rigour", based on anatomical structures, and divided polychaetes into:

qas: question: Who compared annelid genes in 2007?
answers: text: Torsten Struck and colleagues

question: How many annelid genes did Torsten Struck first compare?
answers: text: 3

question: How many annelid genes did Torsten Struck compare for a cross-check?
answers: text: 11

question: What subtypes of polychaetes were useless classifications, according to the 2007 study?
answers: text: Scolecida, Canalipalpata and Aciculata

question: What did Rouse decide leeches were a subgroup of?
answers: text: oligochaetes

question: Who compared annelid genes in 1807?

question: How many annelid genes did Torsten Struck first discover?

question: How many annelid genes did Torsten Struck never compare for a cross-check?

question: What subtypes of polychaetes were useless classifications, according to the 1997 study?

question: What did Rouse decide leeches were a supergroup of?
context: In 2007 Torsten Struck and colleagues compared 3 genes in 81 taxa, of which 9 were outgroups, in other words not considered closely related to annelids but included to give an indication of where the organisms under study are placed on the larger tree of life. For a cross-check the study used an analysis of 11 genes (including the original 3) in 10 taxa. This analysis agreed that clitellates, pogonophorans and echiurans were on various branches of the polychaete family tree. It also concluded that the classification of polychaetes into Scolecida, Canalipalpata and Aciculata was useless, as the members of these alleged groups were scattered all over the family tree derived from comparing the 81 taxa. In addition, it also placed sipunculans, generally regarded at the time as a separate phylum, on another branch of the polychaete tree, and concluded that leeches were a sub-group of oligochaetes rather than their sister-group among the clitellates. Rouse accepted the analyses based on molecular phylogenetics, and their main conclusions are now the scientific consensus, although the details of the annelid family tree remain uncertain.

qas: question: How many previously-separate phyla did the 2007 study reclassify?
answers: text: 3

question: What did the 2007 study decide was the parent group for annelids?
answers: text: Polychaetes

question: What offshoots of polychaetes are unsegmented?
answers: text: echiurans and sipunculan

question: What offshoots of polychaetes are only segmented in the rear?
answers: text: pogonophores

question: What nervous system structure is less univeral among annelids than was thought before 2007?
answers: text: ladder-like

question: How many previously-separate phyla did the 1837 study reclassify?

question: What did the 2007 study decide was the slave group for annelids?

question: What offshoots of polychaetes are immortal?

question: What offshoots of polychaetes are only segmented in the head?

question: What nervous system structure is less universal among annelids than was thought before 1907?
context: In addition to re-writing the classification of annelids and 3 previously independent phyla, the molecular phylogenetics analyses undermine the emphasis that decades of previous writings placed on the importance of segmentation in the classification of invertebrates. Polychaetes, which these analyses found to be the parent group, have completely segmented bodies, while polychaetes' echiurans and sipunculan offshoots are not segmented and pogonophores are segmented only in the rear parts of their bodies. It now seems that segmentation can appear and disappear much more easily in the course of evolution than was previously thought. The 2007 study also noted that the ladder-like nervous system, which is associated with segmentation, is less universal previously thought in both annelids and arthropods.[n 2]

qas: question: What superphylum are annelids in?
answers: text: protostomes

question: What is the other superphylum besides protostomes?
answers: text: deuterostomes

question: What superphylum are vertebrates in?
answers: text: deuterostomes

question: What does 'Articulata' mean?
answers: text: jointed animals

question: What are lophophores?
answers: text: fan-like feeding structures

question: What superphylum are annelids now excluded from?

question: What is one of many superphylums besides protostomes?

question: What superpower are vertebrates in?

question: What are lophosmores?
context: Annelids are members of the protostomes, one of the two major superphyla of bilaterian animals – the other is the deuterostomes, which includes vertebrates. Within the protostomes, annelids used to be grouped with arthropods under the super-group Articulata ("jointed animals"), as segmentation is obvious in most members of both phyla. However, the genes that drive segmentation in arthropods do not appear to do the same in annelids. Arthropods and annelids both have close relatives that are unsegmented. It is at least as easy to assume that they evolved segmented bodies independently as it is to assume that the ancestral protostome or bilaterian was segmented and that segmentation disappeared in many descendant phyla. The current view is that annelids are grouped with molluscs, brachiopods and several other phyla that have lophophores (fan-like feeding structures) and/or trochophore larvae as members of Lophotrochozoa. Bryzoa may be the most basal phylum (the one that first became distinctive) within the Lophotrochozoa, and the relationships between the other members are not yet known. Arthropods are now regarded as members of the Ecdysozoa ("animals that molt"), along with some phyla that are unsegmented.

qas: question: Which Lophotrochozoa phyla have similar egg development?
answers: text: annelids, molluscs, nemerteans and flatworms

question: How do the cells of Lophotrochozoa eggs arrange themselves?
answers: text: after the 4-cell stage, descendants of these 4 cells form a spiral pattern

question: What is the Lophotrochozoa spiral egg-cell pattern sometimes called?
answers: text: spiral determinate cleavage

question: Which Lophotrochozoa phyla have no egg development?

question: How do the cells of Lophotrochozoa eggs destroy themselves?

question: What is the Lophotrochozoa spiral egg-cell pattern required to be called?

question: What animal contains no cells?

question: What phyla is no longer able to make eggs?
context: The "Lophotrochozoa" hypothesis is also supported by the fact that many phyla within this group, including annelids, molluscs, nemerteans and flatworms, follow a similar pattern in the fertilized egg's development. When their cells divide after the 4-cell stage, descendants of these 4 cells form a spiral pattern. In these phyla the "fates" of the embryo's cells, in other words the roles their descendants will play in the adult animal, are the same and can be predicted from a very early stage. Hence this development pattern is often described as "spiral determinate cleavage".