The Zoologist/4th series, vol 2 (1898)/Issue 683/Notes on the Habits of some of the Australian Malacostracous Crustacea

by David George Stead

 

NOTES on the HABITS of some of the AUSTRALIAN
MALACOSTRACOUS CRUSTACEA.

By David G. Stead.

 

Of the habits of these animals hitherto very little has been known. In descriptions of any animals it always seems to me that an insight into their habits and mode of living is quite, or very nearly, as valuable as the scientific diagnosis; but this is the part that is almost invariably neglected. Indeed, many species have been named from old and faded specimens whose proper habitat was not known. Though this is not intended as a "descriptive" paper, I have thought it advisable to place the species in systematic order. Of course, the species enumerated form but a very small portion of those known, there being about 550 recorded species of the Malacostraca in Australia.

 

Order Podophthalmata.
Sub-order Brachyura.
Tribe Oxyrhyncha.

1. Halimus tumidus (Dana).—This species lives at a depth of from one to three feet below low-tide mark, where it is to be found on or under stones that are covered with seaweed. It is hardly possible to distinguish it unless it is in motion, as the carapace and ambulatory limbs are covered with seaweed of the same kind as that which surrounds it. The seaweed is held on to the Crab by means of the hooked hairs which cover it. Rather common in Port Jackson.

 

Tribe Cyclometopa.

2. Ozius truncatus (M.-Edw.).—This is a species which, as will be at once observed by its conformation, is adapted to living amongst loose stones in rocky situations. There are three wellmarked varieties; one, the commonest, being an uniform deep red, with black fingers; another a bluish-grey mottled variety; and the other white, which is only found of a small size.

3. Pseudocarcinus gigas (M.-Edw.). "The Giant Crab."—As its specific name implies, this is a giant amongst crustaceans, the carapace sometimes reaching a breadth of two feet. On account of the enormous size of the chelæ, it can give a tremendous crush—we cannot call it a "nip"—with those weapons. Its habitat is Bass's Strait, between Tasmania and Victoria, where it lives amongst stones, for which it is well adapted, as, if it kept perfectly still, there would be some difficulty in discriminating between the stones and the Crab. The colour varies from red to yellow, with black fingers.

4. Pilumnus fissifrons (Stimps.).—This small species frequents stones, &c. (just below low-tide mark), which are covered with mud and algae, and is common around the shores of Port Jackson. The carapace being very setose, catches and holds sediment, thus giving the Crab the appearance of a small round protuberance on the stone which it frequents.

5. Pilumnopeus serratifrons (Kin.).—Common on rocky shores of Port Jackson and other inlets along the coast of New South Wales, especially in those parts that are covered with small stones, under which they seek concealment. They are subject to a good deal of variation in colour. Length of carapace, ¾ in.; breadth, 1 in. Found along the east coast of Australia, and in New Zealand.

6. Leptodius exaratus (M.-Edw.).—May be procured in similar situations to the preceding, but is not very common. The carapace is very flat, and the last pair of ambulatory legs is twisted upwards to enable it to grasp the under surface of stones, under which it has sought refuge. In coloration it varies according to situation, some being white, others mottled, and others quite black.

7. Neptunus pelagicus (M.-Edw.).—A species which is very widely diffused, undergoes a good deal of variation, and is very abundant. It is the common Edible Crab of the Sydney fish-market. One peculiarity which I have noticed is that the sexes for the most part of the year live strictly apart. I have seen at one time scores of females with not one male among them, and vice versa. To be quite sure, I enquired of the fishermen whether they put them in separate heaps, but they assured me that they did not. This form is very nearly allied to the Lupa bellicosa of America.

8. Neptunus sanguinolentus (M.-Edw.).—This species is rather common, and specimens of a small size are extremely abundant. But few of them arrive at a large size. This falling-off, I think, is mainly due to the attacks of its congener the quarrelsome and almost ubiquitous N. pelagicus, which species is a great check on the diffusion and growth of very many of the pelagic Crustacea. Not being so good—from an epicurean point of view—as N. pelagicus, it is but little sought after. It has an extremely beautiful appearance, the carapace showing iridescent colours, and having on it three spots like drops of blood, surrounded by bluish white rings, one on either side on the epibranchial regions and one almost on the posterior border of the carapace, over the intestinal region. It leads a pelagic life, and is widely disseminated.

9. Charybdis cruciatus (Herbst.).—This is, in my opinion, the most beautiful of our Crustacea. When fresh, its rich tints cannot be surpassed by anything in Nature. It may be seen occasionally in company with N. pelagicus at the fish-market, but is very uncommon. I have never found it in its young state.

10. Scylla serrata (De Haan).—This is the largest Crab to be seen in the Sydney fish-market. Like N. pelagicus, it is pelagic, but is not nearly so common. The carapace is generally of a dark green colour. It has a wide distribution, reaching from Japan to Australia. Around the anterior border of the carapace there is a row of sharp conical spines. Any refractory prisoner is quickly put an end to by being pressed against these.

11. Thalamita sima (M.-Edw.).—Does not attain a large size, and is essentially pelagic. It is rather common in our bays and harbours. Carapace and chelae shortly setose, and of a greenish hue.

12. Thalamita admete (Herbst.).—This is a very small pelagic Crab. I have observed it in tiny pools in rocky situations at Port Jackson.

13. Nectocarcinus integrifrons (M.-Edw.).—Though adapted for a free-swimming existence, this species lives to a great extent on the bottom in shallow water, amongst seaweed. It is not of uncommon occurrence for green Fucus to be found growing on its legs and carapace, which are very setose. East coast of Australia and New Zealand.

14. Platyonychus bipustulatus (M.-Edw.).— This pelagic species is very common in its young state, but a great many must fall a prey to their many enemies, amongst the chief of which may be reckoned Neptunus pelagicus, as large ones are of rare occurrence. One that I have procured measures 10 centimetres across the carapace, but specimens of this size are seldom found. It has a wide distribution: East coast of Australia, New Zealand, Japan, and China.

 

Tribe Catametopa or Grapsoidea.

15. Macrophthalmus setosus (M.-Edw.).—This species is essentially a burrowing one, frequenting mud-flats. Its burrows, may be found here and there among those of Helæcius cordiformis (q.v.), but cannot be mistaken for the latter on account of the acute angle it makes with the surface, whereas the burrows of H. cordiformis are vertical and smaller. Colour yellowish brown, covered with setæ. Port Jackson, New South Wales. Common.

16. Helæcius cordiformis (Dana).—Found in similar situations to the preceding, but is much more common. The mud-flats, where these animals dwell, possess a most animated appearance, and remind the observer very forcibly of a busy city, of which the soldiers are Mycteris longicarpus (q.v.) and the civilians H. cordiformis (of which there are myriads), and all their little legs moving in concert make quite a great clatter. They are extremely amusing. On anyone approaching they show fight at once, holding up their comparatively large "nippers" as high as they can, so that as they retreat—which they do with their "faces to the foe"—they very often roll over backwards, so eager are they to show their weapons. The very rotund body is of a deep reddish brown colour. New South Wales, Tasmania.

17. Ocypoda cordimana (Desm.).—The Crabs of this genus are noted for their extreme swiftness of foot; indeed, they run so fast, and their colour assimilates so well with the sand, that they appear like pieces of cotton-wool or feathers being blown along by the wind. They are found wherever there is a good stretch of sandy beach, in which they make their burrows. These burrows average about 2 ft. in depth. East coast of Australia.

18. Grapsus variegatus (Latr.).—This is, without doubt, the dominant species of Crustacea in Australian waters, is distributed over a wide area, and presents great variation. They are found in great numbers all along the rocks at low tide, but scurry off into the crevices with great rapidity when disturbed. Though not pelagic, their flattened legs enable them to swim very well. They vary in colour from a deep green with faint yellow streaks to a bright yellow and red. Coast of Australia, New Zealand, Norfolk Island, California, and Chili.

19. Pachygrapsus transversus (Gibb.).—Inhabits short seaweed about midway between high- and low-tide marks. It is also obtained in crevices of rocks amongst small stones, and amongst sessile ascidians. In appearance it is something like a small specimen of G. variegatus, but may be at once distinguished by the bristles which clothe the legs. Port Jackson.

20. Cyclograpsus Lavauxi (M.-Edw.).—Common round Port Jackson in situations where the shore is covered with clean stones—i.e. stones free from algæ and mud—nearly at the limit of high tide. They are very interesting, especially in the operation of disengaging them from your fingers, which is no easy matter if they once get a good grip. The colour is a beautiful red dorsally, with white on the ventral side. Port Jackson.

21. Chasmagnathus lævis (Dana).—Found as a rule in muddy situations wherever there are stones, under which it burrows. It also avails itself of the burrows made by Macrophthalmus setosus. Colour deep brown, dotted on the carapace with yellow. Port Jackson.

22. Sesarma erythrodactyla (Hess.).—The observer will be at once struck with the great disparity in coloration between the male and female. The female is always a dull brownish colour, while the male exhibits great variation, the carapace being sometimes a brilliant green. The chelse in both sexes are tipped with red. Common on mud-flats under stones. Port Jackson.

23. Plagusia chabrus (Miers).—This species inhabits the short red seaweed which clothes the rocks just below low-tide mark. It is very seldom seen to leave the water of its own accord, but, if it does so, returns almost immediately. It subsists chiefly on vegetable matter (Fucus and algæ), but consumes animal matter whenever it is available. The outstretched limbs cover an expanse of about 10 in. The carapace and dorsal aspect of ambulatory limbs are covered with a short dense red pubescence. Widely distributed: Port Jackson, New South Wales; Tasmania, New Zealand, Cape of Good Hope, and Chili.

24. Plagusia glabra (Dana).—Rather common along the coast of New South Wales, where it is found in small rock-pools and crevices at low tide. It does not often leave the water, and is essentially a vegetarian. Legs and body are far more rotund than the preceding, and not at all setose. I am without doubt that Milne-Edwards' description of Heterograpsus octodentatus has been drawn from the young of this species. There is a great difference between the colour of old and young specimens. Young ones are chiefly of a yellowish tinge, with black spots; while old ones are of a very dark colour, with traces of yellow on the metabranchial regions. They form most handsome objects in the water when the sun is shining on them, showing up their beautiful tints. Port Jackson, New South Wales.

25. Mycteris longicarpus (Latr.).—Commonly designated the "Soldier Crab." It is at once a marvellous and strange sight to see thousands of these crustaceans on the low mud-sand-flats, marching about in regular battalions after the tide has ebbed. Scarcely ever is one to be seen singly but it is scurrying off to meet a company; and here and there will be seen an extra large one, acting no doubt as an officer. Their military appearance is considerably heightened by the colours, which are as follows:—branchiostegites dark blue (these being very prominent); remainder of carapace pale blue; legs yellow, with a red band at each joint. Third pair of maxillipedes very large. Port Jackson; Victoria.

26. Mycteris platycheles (M.-Edw.).—This species is found in very similar situations to the preceding, but has not so great a propensity for travelling in companies. Port Jackson.

27. Hymenosoma varium (Hasw.).—This minute species undergoes a good deal of variation, and inhabits many different situations. Most frequently it is found in short seaweed just below low water, though I have procured it from amongst minute pebbles and from mud. Some specimens are beautifully marked. East coast of Australia, Tasmania, and New Zealand.

 

Sub-order Macrura.
Tribe Anomala.

28. Eupagurus sinuatus (Stimpson).—This is one of the commonest and most beautiful of our Hermit Crabs, frequenting rock-pools. In choosing its domicile it seems to have a decided partiality for the shell of Purpura succincta. It may often be found in the act of house-hunting, though in general choosing a shell a few sizes too large, so that there is no need to make a change until several ecdyses, or moults, have taken place. Port Jackson, Bondi, New South Wales.

29. Paguristes barbatus (Hell.).—Another of the "Hermits"; not so common nor so large as the preceding. I have found it inhabiting the shells of Purpura succincta, Monodon zebra, and Neritina punctata. Port Jackson.

30. Porcellana dispar (Stimp.).—This species frequents stones covered with mud and alga3 that are found just below low-tide mark. If one of the stones be picked up out of the water these crustaceans will not, at first, be observed, as they appear precisely similar to dirty little pieces of seaweed or mud as they slide down towards the water. Very common round the shores of Port Jackson. The carapace is about three-sixteenths of an inch in width.

 

Tribe Thalassinidea.

31. Callianassa sp.?—Inhabits the same localities as Mycteris longicarpus, but burrows deeper, and subsists on mud-worms. Though it is classed amongst the Podophthalmatous Crustacea, its eyes, which are reduced to mere dots, are sessile. This is not to be wondered at, inasmuch as it has very little need for eyesight, spending as it does most of its time burrowing, and but rarely coming to the surface. In colour it is of a yellowish pink, as a rule, but is sometimes white. Port Jackson; not very common. Length, 2½ in. from rostrum to telson; large cheliped, 1½ in. long.

 

Tribe Scyllaridea.

32. Ibacus Peronii (Leach).—The members of this species pass most of their time on a muddy bottom, in not very shallow water. They are of a beautiful salmon-colour. Length, 9 in. Rare. Port Jackson.

33. Palinurus Hugelii (Hell.).—Closely allied to the British Rock Lobster (P. vulgaris). It is the common Sydney Crawfish, and sometimes grows to the length of 24 in. Subsists on a vegetarian diet, viz. fibrous marine plants. Rocky coasts of New South Wales.

 

Tribe Astacidea.

34. Astacopsis serratus (Shaw).—This animal has been given different names by different naturalists, on account of some of them getting large and some small specimens. In large examples the abdominal somites are each armed with a row of strong conical spines, but in young specimens these are either rudimentary or quite absent. There are also other differences. It is distributed with some variation over most parts of New South Wales. The colour, which also varies, is most commonly of a deep red. Attains a length of 18 in. Huxley mentions it in his book, 'The Crayfish,' under the name of "Australian Crayfish."

 

Tribe Penæidea.

35. Penæus canaliculatus (Oliv.).—This is truly a handsome species, having, when alive, the most delicate tints, and sometimes growing to the great length (for a Prawn) of 10 in. It is one of the principal Prawns of the Sydney fish-market, but is not so common as its congener, P. esculentus. Port Jackson; Botany Bay; Japan.

36. Penæus esculentus (Hasw.).—The common Prawn of Sydney, and caught in great numbers with the nets. This genus is remarkable for the large membranous appendage attached to the base of the first pleopod of the male, and called by SpenceBate the "petasma," or curtain. In the female this appendage is quite rudimentary. Port Jackson; Port Darwin. Incidentally it might be mentioned that when the term "Prawn" is mentioned the genus Penæus is meant; Palæmon, to which the English Prawn belongs, not being known here as an article of diet.

 

Tribe Caridea.

37. Rhynchocinetes typus (M.-Edw.).—This species surpasses in beauty any crustaceans that I have ever observed, the body being a beautiful semi-transparent tint, with here and there spots of light blue dotted over it. The chelæ are red with white dactyli. Altogether it is most disappointing to see their magnificent colours fade so much when the animals are preserved. They frequent semi-dark situations below low-tide mark, and if taken and put in a bottle containing sea-water die in a very short time, though (as stated elsewhere) I have kept specimens of Leander intermedius, an allied form, for a week in the same bottle. At present the only way I can account for it, is, that the light, coming as it does through the sides of the bottle, is too strong for them, or that they require a constant stream of water. It could not be a question of difference of pressure, as they are procured in shallow water. Though darting away at the slightest movement, a person may attract them by keeping his hand in the water for some time, when they will presently be seen issuing in numbers from all the cracks and crannies, though before not one was visible. They must be attracted by their sense of smell, as I have often seen them advancing steadily towards my hand when there was no possible chance of them seeing it. A good deal of reconnoitring is done before they make up their minds to come close, and then the smallest specimens always come first. Altogether this species forms one of the most interesting and amusing of the Crustacea. Port Jackson; New Zealand; Chilé.

38. Alpheus Edwardsii (White).—These crustaceans are rather common in Port Jackson, and are familiarly known as "Nippers." They may be caught in tiny rock-pools under stones at low tide, and are also procured in nets, in company with Penceus esculentus. They are very remarkable for their habit of making a sharp clicking noise with the large chela when caught or irritated. The sound resembles that made by cocking a pistol very quickly, and, if the animals happen to be in a bottle, you really have to look every now and again to make sure that it is not being cracked to pieces, so sharp is the sound. Colour, light green on carapace, and traces of red on abdominal somites.

39. Leander intermedius (Stimp.).—Common all along our coast in small rock-pools (left by the tide as it recedes), in which, if disturbed, they seek the shelter of any small stones which are lying about. They are very hardy, as I have well proved. I kept a few of them alive in a bottleful of sea-water for a week without once changing it, while some specimens of Rhynchocinetes typus which were put in at the same time died within three or four hours. This difference, which I have noticed repeatedly, is hard to account for. The integument is translucent, and covered with small red spots, which are noticeable even upon the embryo within the ovum.

40. Alope palpalis (White).—May be found in shady nooks amongst the rocks at low tide, but is not at all common. It must also occasionally swim freely, as I have taken it from the stomach of the "Jew-fish" (Sciæna antarctica). Covered with short red setæ. Palpi very large. Port Jackson.

 

Tribe Stomatopoda.

41. Squilla lævis (Hess).—The common "Hass-crab" of Port Jackson. Caught principally in the Prawn-nets, travelling in company with Penæus esculentus, on which it partly subsists. It may often be procured from the stomach of Sciæna antarctica, of which fish it forms one of the principal articles of food. Coast of New South Wales.

 

Order Edriophthalmata.
Suborder Isopoda.
Tribe Flabellifera.

42. Ceratothoa trigonocephala (Leach).—This is the commonest and best known of our fish parasites. As a rule, it inhabits the mouth of the "Yellow-tail," Trachurus declivis (C. & V.). The head is almost triangular, and deeply encased in the anterior portion of thorax. The Ceratothoa embryo is very different to the adult. The five segments of the pleon, which in the adult have coalesced, are movable upon each other. Pleon is nearly as long as pereion, but in the adult it is so insignificant as to be scarcely so long as one pereion somite. The telson too widens out posteriorly when the animal reaches maturity. Altogether the young Ceratothoa is fitted for a free existence, and no doubt the adult was the same at one time, but has been gradually adapted to living a parasitic life, thereby undergoing change of formation. Colour white. Port Jackson.

43. Nerocila sp.?—This Isopod is another of the parasitic Crustacea, having for its host the Sea-mullet, Mugil grandis (Cast.). It is not so convex as the preceding species, and the epimera are very long. Eyes are entirely wanting. Colour sometimes dark brown, also yellow.

44. Cymodocea pubescens (Hasw.).—The small crustaceans of this name are "rock-borers." The boring is done exclusively with the uropods, which form two strong spikes. In burrowing they do not go in head first, but stand on the one place, simply turning round and round, as if on a pivot, with their uropods lowered and cutting as they go. They no doubt assist very materially in the disintegration of the rocks, honeycombing them to such an extent that they are easily broken up by the waves into sand, and so contribute to form the rocks of a future geological period. When these Isopods are captured they draw themselves up into a ball, and project their uropods, which are very strong and sharp. Fawn-colour along dorsal line, reddish brown at sides, of somites. Port Jackson.

 

Sub-order Amphipoda.
Tribe Grammarideæ.

45. Talorchestia quadrimana (Hasw.).—This is the common Sand-hopper, found in great numbers along the whole coast of New South Wales, wherever there are masses of decaying vegetable or animal matter. Length, 7 lines.