NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
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Scientific Memoirs by
the body—this enormous appendage being used, at least in one species, as a love
-signal, as a war-club, and also as a buckler.
The Indian species of Gelasimus are ten in number, but the only one that I
have had opportunities of observing in a state of nature is Gelasimus annulipes.
This species, which has an extensive range over the Indo-Pacific region, from the
shores of East Africa to the Sandwich Islands, is to be found in vast warrens, in
which the males far outnumber the females, on the extensive tidal mud-flats of the
Godavari and Kistna deltas. If one lands here in the early months of the year,
one becomes aware of a multitude of bright twinkling objects which, when one
advances to examine them, suddenly disappear : these objects are the brandished
chelipeds of Gelasimus annulipes, and their disappearance is caused by the crabs
retreating in alarm into their burrows.
If one remains perfectly quiet the crabs in time cautiously come out again and
resume their occupation. The males, being so vastly more numerous than the
females, attract attention first, and their behaviour is something quite grotesque.
They dance round the mouths of their respective burrows, keeping up a continual
beckoning motion with the big chela, which is of a beautiful cherry-red and rose-
pink colour. Here and there a little dingy female may be seen picking at the mud
near her burrow, and at last it becomes evident that the singular demonstrations
of the males are intended for the female in their vicinity ; for if the female should
approach one of the males the excitement of that favoured individual becomes
almost frantic. lf, on the other hand, one male should skirmish near another, a
fight takes place, the little creatures making savage backhanded sweeps at one
another. No doubt they claw each other too, for on going over the field of action
dismembered chelipeds are seen lying about.
There can be little doubt that in Gelasimus annulipes the courtship of the
female by the male and the consequent rivalry between the males, is as sustained
and as complicated a piece of work as it is among many higher animals, and that
to this fact the cheliped of the male probably owes its brilliant colouring (to attract
the female) and its enormous size (for giving and warding-off blows).
My only opportunities of observing Gelasimus have been at the courting
season, during the cold-weather months ; but the ordinary habits of the American
Fiddler-crabs have been graphically described by McNair Wright in the American
Naturalist for May 1887 (Volume XXI, pages 415-418), and by Kingsley in the
same serial for 1888 (Volume XXII, pages 889-893).
4. On the Habits of some Indian species of Ocypode Crabs.
The crabs of the genus Ocypoda resemble their near relatives of the genus
Gelasimus, both in their suggestive geographical distribution and in their manner
of life.
Medical Officer of the Army of India.
69
They are gregarious and amphibious, living in warrens, each individual hav-
ing a burrow of its own. Though, as a rule, they do not wander far from their
burrows into which, when alarmed, they fly with wonderful speed, they may some-
times be seen marching together in large companies across the sand.
As has been pointed out by many observers, both sexes are alike in having
one of the chelipeds greatly enlarged, and in all the species but one there is, on
the " palm " of the longer cheliped, a series of fine teeth forming a sort of file
which can be scraped across another more or less distinct ridge on the ischiopodite
of that cheliped. The whole organ has a general resemblance to the stridu-
lating apparatus of certain insects, and indeed it is usually spoken of as the
" stridulating-ridge " or " musical organ." So far as I know, however, the
sound that this stridulating organ is capable of producing has been actually
heard only by Dr. Ortmann, Captain A. R. S. Anderson and myself. I shall
refer to it again in the section on Sounds produced by certain Marine Animals.
Five species of Ocypoda occur on the shores of India and its islands. I
here wish to mention only Ocypoda rotundata, which is found in the neighbour-
hood of Karachi, and O . ceratophthalma, which occurs throughout the Pacific
from the east coast of Africa to the Sandwich Islands. These two species, so
far as our observations on the " Investigator " go, are peculiar in not always
digging deep burrows, but sometimes only partially burying themselves in hollows.
O . ceratophthalma when thus crouching part-buried, looks like a stone embed-
ded in the sand, a fact which appears to be of interest as suggesting that the
habit of seeking protection by burrowing deeply may have been the outcome of
a habit of scratching a hollow in which to crouch in a lifeless attitude.
5. Some Protective Disguises among the Higher Crustacea.
The last paragraph leads us on naturally to this subject, which is so large
a one that, if it were to be fully treated, nearly half the higher Crustacea of
these seas might be mentioned. Moreover the subject has no particular novelty,
so that I shall confine myself to the statement of a few specific instances in
which I myself have observed the efficacy of protective colouration, sculpture,
and attitude.
Of the small feeble and defenceless crabs that live among coral shingle
off certain rocky parts of the coasts of India and Ceylon, there are many species
which, at first sight, look exactly like little bits of dead coral : they have the
same mottled colouration, the same worm-eaten appearance, and often also they
are encrusted with foraminiferal growths of some species of Polytrema. When
the multifarious contents of the trawl are turned out on deck these little crabs.
lie motionless in unlife-like attitudes, and might easily escape notice among the
bits of shingle.
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Among Oxystome crabs that have this singularly effectual disguise are
Oreophorus reticulatus and alcicornis, Actœomorpha morum and lapillulus,
Tlos petrceus and patella, and Heterolithadia fallax.
Among Oxyrhynch crabs, Parthenope horrida and investigatoris, all the
species of the sub-genus Parthenolambrus and several of the species of the
subgenera Rhinolambrus and Platylambrus.
Even among the Cyclometopes, which, as a group are fierce and active
crabs, there are some that have this protective resemblance to the inanimate
objects among which they shelter themselves : such are several of the species of
Carpilodes (notably C. cariosus), of Lophactœa, of Leptocius and of Actœa (not-
ably A. f l o s c u l a t a ,
A .
e c h i n u s ,
A .
n o d u l o s a , A . f o s s u l a t a ) .
Among Catometopes, I only know of one genus that leads a retiring life
among coral-shingle at the bottom of the sea, and that is the aberrant P a l i c u
(Cymopolia): two, at least, of the Indian species of this genus might easily be
mistaken for flakes of eroded coral-rock.
Others of these small shingle-haunting crabs have a striking resemblance to
another common constituent of the shingle of tropical seas, namely, broken shells,
discoloured and encrusted. I have noticed this form of protective disguise in
several species of the Oxystome genera Nursia and Nursilia, and in the
Oxyrhynchs Cryptopodia, Heterocrypta and Micippa.
In all the foregoing cases the disguise may be supposed to be the passive
results of sculpture and colouration coming out on a torpid organism. In other
cases—too well-known and too numerous to refer to—weak and inoffensive crabs
of a sluggish habit take steps, as if by design, to conceal themselves, The
Oxyrhynch crab Camposcia retusa, which covers itself with a patchwork coat
of scraps of sea-weed, is one of the best known illustrations of this apparently
deliberate method.
Every naturalist must have observed instances for himself : I may mention
the two best cases that have come to my notice, namely, the two Oxyrhynchs
Chlorinoides longispinis and Macrocœlonma nummifer. Both these species make
great use of the shells of Orbitolites in constructing their protective mantle.
But in Chlorinoides longispinis the carapace is also armed with long slender
spines, each of which ends in an elegant knob, and when the crab is covered with
Orbitolite shells and pieces of sea-weed, these curious spines stick out, as from an
encrusted rock, like a group of Hydroid polyps with their tentacles retracted.
The singular form of the carapace of the female of the Oxyrhynch crab
Huenia proteus, is undoubtedly a protective disguise of a similar kind. The
carapace is flat and depressed, and its angles are produced to form rather rag-
ged crinkled lobes, which both in form and colour resemble fronds of fucus.
Medical Officers of the Army of India. 7 1
The "Investigator" has, so far, dredged only one female specimen of Huenia
proteus, and on the carapace of that specimen a small fucus, with fronds just
like these lobes, was growing.
Possibly some of the cases previously mentioned as doubtful instances of
commensalism,—those cases, namely, in which small crustacea sheltering among
Zoophytes and Echinoderms are coloured almost exactly like their hosts—might
more rightly be classed as illustrations of protective disguise.
Among the macrurous decapod Crustacea simple protective colouration is
well known to be extremely common, especially in those that live on a sandy or
shingly sea-bottom. My own experience is limited, but I have noticed that in
Sicyonia, Scyllarus, Pontocaris, and even in some of the smaller species of
Peneus, which are dredged on shingle and broken shells, sculpture and attitude
largely aid colouration in forming a suitable disguise.
6. On the Geographical Distribution of Varuna literata, Plagusia squamosa,
and Carcinus mœnas.
The wide distribution of these two species of Grapsoid crabs, over the whole
Indo-Pacific in the case of Varuna literata, and over the whole Indo-Pacific
and tropical Atlantic in the case of Plagusia squamosa, is well known to all
carcinologists. When serving on the "Investigator" I made a point of examin-
ing drift timber, and I do not think that I ever saw a drift log that was not ten-
anted by one or both of these crabs, sometimes in a swarm. On the ship herself,
which is of wood, we generally carried one or two individuals of Plagusia squa-
mosa, adhering to the side near the water-line.
Such logs would be often encrusted with barnacles and with tenacious sheets
of fish-spawn, upon which the crabs may perhaps have fed: on the other
hand they were sometimes shadowed by shoals of fish, which may have been
dangerous for the crabs. I think therefore that the wide range of these two
species is due to the dispersal of drift timber by ocean currents and perhaps also
to ships of trade.
The remarkable distribution of the Portunoid crab Carcinas mœnas, how-
ever, a species that haunts rocks and sea-weed and does not take to the open
sea, cannot be explained in this way.
Carcinas mœnas has been found at various places on the Atlantic coast of
America from New England to Pernambuco ; it is the common shore-crab of the
British Islands, and is found in the North Sea, the Baltic, and on the Atlantic
coasts of Europe ; it is common in the Mediterranean, and has been found in the
Black and Red Seas ; it has been found on the Ceylon coast, and it has been
T
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reported from the Sandwich Islands and the Bay of Panama. Its occurrence in
Australia is doubtful.
This wide geographical range, considered as an isolated fact, is so strange
as almost to suggest some mistaken identifications, but as I have compared the
Indian specimen with specimens from the Mediterranean and the North Sea,
there is no doubt about its occurrence in these seas. Moreover, it is not an
isolated fact. In the Summary published in these Memoirs in 1899, as well as
in the Account of the Investigator Deep Sea Madreporaria, and in still more
detail in the Account of the Investigator Deep Sea Fishes, I have collected a
number of instances of fishes and Marine Invertebrates that have a somewhat
similar distribution, and have shown the bearing of the whole mass of evidence
upon Suess theory of the wide-spreading Mediterranean Sea of Tertiary times.
V.—Some Instances of Protective and Warning Colouration.
I have already, under the headings of Commensalism and Miscellaneous
Notes on stalk-eyed Crustacea, mentioned some remarkable cases of protective
colouration and sculpture that have come to my notice. Many more could be
mentioned, if only the marine fauna of India were individually identified and
named. However, tropical seas are so full of such cases and they are so
accessible to any observant traveller, that—since every one admits the valid-
ity of the theory of protective colouration, and few doubt that warning colour-
ation is one of Nature's approved means to an end—it is hardly necessary
to record all that one observes.
The two following cases of chameleonic colour change for protective
disguise appear to be worthy of record.
The young file-fish Balistes maculatus, as seen swimming in clear water, is
blue black with numerous light blue spots. Three that I once found sheltered in
a piece of dark, discoloured drift-wood were quite invisible, as they had tempo-
rarily occluded their spots and assimilated their colour to that of their refuge.
At first thought it seems little profitable to a fish to be able to change its
colour to that of drift timber. But drift timber is no rare thing in tropical seas,
and Balistes maculatus is one of the species of fishes that always haunts it, being
attracted, I think, by the barnacles that grow on it. But everyone knows that
in seas where sharks abound, the neighbourhood of floating objects is dangerous,
so that this chameleonic faculty of the species must often be useful.
The Scorpaenoid fish Pterois volitans is one of those that gets its living
among rocks encrusted with zoophytes and algæ. Hugging such a rock, its
body mottled like the surface against which it rests, and the filaments of its
Medical Officers of the Army of India.
73
long fin-rays waving like fronds, it does, as I know from experience, often escape
the notice even of those whose business it is to ransack rocks for specimens.
On one occasion I chanced to drive a Pterois volitans from its retreat among
the rocks into the open blue water of a deep pool, whereupon its numerous
cross-bands, which ordinarily show no trace of that colour, immediately became
blue in alternate streaks of dark and light hue.
The Siluroid fish Plotosus arab is able with its stout reversely-serrated
dorsal spine (whether its similar pectoral spines are equally dangerous, or not, I
cannot say) to inflict a wound that, even if promptly treated, can disable a man
for several days, as I know from personal experience. According to Day, the
wound from this spine is said to cause "phlegmonous inflammation, or even
tetanus". The colours of this objectionable fish are usually described as chestnut
brown with two bluish-white longitudinal bands. As a matter of fact, all the
living specimens that I have seen have a most startling uniform of deep purple
brown with two bright yellow bands along the body, suggesting the idea of a
longitudinally-striped hornet. Though I do not know that any experiments have
been made, I am prepared to assert, from my own experience, that this singularly
conspicuous colouration has a warning value. I may mention here that I decalci-
fied and sectioned several specimens, but could find no trace of any special
poison-gland, so that, as is generally stated, it must be the ordinary mucus of
the skin that is poisonous.
The Nudibranch Gastropod Mollusks of the reefs of these seas furnish
many excellent instances of protective colouration, some of those species that
are found on encrusting sponges and soft corals being invisible while on their
hosts. One can also observe on these reefs cases of warning colouration among
Nudibranch Mollusks, more than one showy species having a disagreeable aroma-
tic smell.
The observations of Professor W. A. Herdman on protective and warningly-
coloured Mollusks are so conclusive, that I need not regret my inability to
name the Indian species that I have noticed to be thus protected.
A little species of, I think, the genus Bulla, that is found in tidal pools on
some of the Andaman shores must, however, be specially recorded, as to a
most brilliant colouration of emerald green with bright orange spots, it unites a
most disagreeable and persistent pungent musky odour—an odour so strong
that a little of it will taint a large jar of spirit. The singularly conspicuous
colouration of this species must certainly, I think, be a warning-signal: to a
human being the combination of bright orange and emerald green suggests
danger, at first sight. Its habits are particularly open: whenever I found it,
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it was lying exposed in clear shallow pools, a most conspicuous object in spite
of its small size.
VI.—On the Phosphorescence of Certain Marine Invertebrates.
I do not propose to add anything to the enormous mass of literature that
has accumulated about the luminosity of the sea, but merely to mention certain
specific instances of the production of light.
One of the common Pennatulids of these seas— Cavernularia obesa —emits
brilliant coruscations, as has been observed in several European zoophytes, and
it is quite possible to believe that the light may be useful to attract prey.
The deep-sea Pycnogonoid, Colossendeis gigas, is another animal that I have
observed to be luminous. This is remarkable, since the species is blind and
appears to feed on oceanic mud, so that it probably has no need to capture prey
either by sight or by the use of an alluring light. The specimen that displayed
the light had a span of nearly twenty inches, and was dredged near the Andamans
in 922 fathoms. When placed, ventral surface upwards, in a dark cabin, it shone
like a star, the body and all the legs except the ovigerous pair showing as lines
of persistent blue-green light. This gradually died away, but remained for a long
time illuminating the long fifth and sixth segments of all but the first pair of legs.
Three species of Macrurous crustacea, dredged off the Andamans in 561
fathoms, were observed to be phosphorescent—namely Aristœus coruscans,
Heterocarpus alphonsi, and Pentacheles phosphorus. The light of Aristæus and
Heterocarpus appeared to come as a secretion from somewhere near the openings
of the green glands. The Heterocarpus when handled, as it floated in a bucket
of sea-water in a dark cabin, emitted pale clouds of light which at last lit up the
bucket so that all its contents were visible in the clearest detail, but the luminous
secretion of Aristaeus was neither so bright nor so lasting. In Pentacheles the
light was confined to two points near the openings of the genital ducts.
In Heterocarpus both males and females were luminous : with Aristæus and
Pentacheles we had only females to observe.
The literature on the subject of animal-light is so large that I have given
up the idea of listing it. In the classical paper of Quatrefages ( Annales des
Sciences Naturelles, Zool. (3) XIV, 1850) a list of luminous Invertebrates is given.
VII.—Notes on peculiarities of Food.
The two following cases seem to me worthy of record in a "biological"
paper.
Medical Officers of the Army of India.
75
The file-fish Balistes maculatus, which one often meets far from land, has
been taken by us in the open sea with its, stomach full of P teropods. In its
habit of shadowing drift timber this fish shows decided pelagic proclivities, to
which the Pteropods in the stomach seem also to bear witness.
The most curious feeding that I have ever noticed was in a case of the little
boring sea-urchin Echinostrephus molare, an individual of which species, that I
once dug out of a hole in coral rock in the neighbourhood of a temporary an-
chorage of the "Investigator," was eating boiled rice that had been thrown over-
board. Not only was it eating it, but it had stored up a supply in its burrow.
It will, of course, be said that, the rice must have been accidentally washed
into the burrow during the absence of the sea-urchin, but I satisfied myself that it
would have been difficult for this to take place, and that no other rice was strewn
about in the neighbourhood. As a matter of fact, the discovery of boiled rice in
such a situation was so strange and unexpected that I had to resort to the iodine
test to solve the puzzle.
To discover food, and then to lay up a store of it, perhaps implies the posses
sion of more sensation, activity, and intelligence than most people are willing to
accede to a sea-urchin. But the experiments of Romanes ( Journ. Linn. Soc.
Zool., XVII, 1884) seem to show that star-fishes are guided to food by some
sense akin to smell, a conclusion supported by Prouho ( Archives de Zool. Ex
-perim (2) VIII. 1890, page xxxvi) who localizes this sense in the tube-feet at
the end of the rays. Prouho ( Arch. Zool. Exper. v. 1887, page 229) had pre
viously noticed that the sea-urchin Dorocidaris papillata is omnivorous, and
exercises some intelligence in the search for food. Sluiter (v. Natuurkund.
Tijdschr. Nederland-Ind. XLVIII, 1889, page 285) mentions a sea-urchin that
showed considerable activity in an aquarium, and a star-fish that displayed a
certain amount of dexterity. Nagel ( Biologisches Centralblatt, 1894, page. 543)
maintains that Echinoderms, like many other marine animals, can taste and smell
.
VII.—Stray Notes on Sauropsida.
Among the few observations that I had an opportunity of making, perhaps
the following are worthy of record.
In April 1889 I was fortunate enough, when looking for Birgus latro on
South Sentinel Island, to witness the actual hatching out of a brood of young
green-turtles. I was attracted by a violent commotion in the loose sand above
ordinary high water-mark, which was presently explained by the emergence of a
swarm of young turtles, who all with one consent made for the sea, with an
unerring instinct. If one of the little creatures was turned head to land, it imme-
diately righted itself again.
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