[526a1] In the crayfish the male differs from the female: in the female the first foot is bifurcate, in the male it is undivided; the belly-fins in the female are large and overlapping on the neck, while in the male they are smaller and do not overlap; and, [5] further, on the last feet of the male there are spur-like projections, large and sharp, which in the female are small and smooth. Both male and female have two antennae in front of the eyes, large and rough, and other antennae underneath, small and [10] smooth. The eyes of all these creatures are hard, and can move either to the inner or to the outer side. The eyes of most crabs can do the same, to an even greater degree.
The lobster is all over grey-coloured, with a mottling of black. Its under feet, up to the big feet, are eight in number; then come the big feet, far larger and flatter [15] at the tips than the same organs in the crayfish; and these are irregular: the right claw has the extreme flat surface long and thin, while the left claw has the corresponding surface thick and round. Each of the two claws, divided at the end like a pair of jaws, has both below and above a set of teeth: only that in the right [20] claw they are small and saw-shaped, while in the left claw those at the apex are saw-shaped and those within are molar-shaped, these latter being, in the under part, four teeth close together, and in the upper part three teeth, not close together. Both right and left claws have the upper part mobile, and bring it to bear against the [25] lower one, and both are curved, being thereby naturally adapted for apprehension and constriction. Above the two large claws come two others, covered with hair, a little underneath the mouth; and underneath these the gill-like formations in the region of the mouth, hairy and numerous. These organs the animal keeps in perpetual motion; and the two hairy feet it bends and draws in towards its mouth. [30] The feet near the mouth are furnished also with delicate appendages. Like the crayfish, the lobster has two teeth, and above these teeth are its antennae, long, but shorter and finer by far than those of the crayfish, and then four other antennae similar in shape, but shorter and finer than the others. Over these antennae come [526b1] the eyes, small and short, not large like the eyes of the crayfish. Over the eyes is a peaky rough projection like a forehead, larger than the same part in the crayfish; in fact, the frontal part is more pointed and the thorax is much broader in the lobster than in the crayfish, and the body in general is smoother and more full of flesh. Of [5] the eight feet, four are bifurcate at the extremities, and four are undivided. The region of the so-called neck is outwardly divided into five divisions, and sixthly comes the flattened portion at the end, and this portion has five flaps; and the inner parts, into which the female drops her spawn, are four in number and hairy, and on [10] each of the aforesaid parts is a spine turned outwards, short and straight. The body in general and the region of the thorax in particular are smooth, not rough as in the crayfish; but on the large claws the outer portion has larger spines. There is no apparent difference between the male and female; for they both have one claw, [15] whichever it may be, larger than the other, and neither male nor female is ever found with both claws of the same size.
All crustaceans take in water close by the mouth. The crab discharges it, closing up, as it does so, a small portion of the same, and the crayfish discharges it [20] by way of the gills; and the gill-shaped organs in the crayfish are very numerous.
The following properties are common to all crustaceans: they have in all cases two teeth (for the front teeth in the crayfish are two in number), and in all cases there is in the mouth a small fleshy structure serving for a tongue; and the stomach is close to the mouth (except that the crayfish has a little oesophagus in front of the [25] stomach),5 and there is a straight gut attached to it. This gut, in the crayfish and its congeners, and in the carids, extends in a straight line to the tail, and terminates where the animal discharges the residuum, and where the female deposits her eggs; in the crab it terminates where the flap is situated, and in the centre of the flap. And in all these animals the eggs are deposited outside.6 Further, the female has the [30] place for the eggs running along the gut. And, again, all these animals have an organ, larger or smaller, termed the mytis or poppy.
We must now proceed to review their several differentiae.
The crayfish then, as has been said, has two teeth, large and hollow, in which is [527a1] contained a juice resembling the mytis, and in between the teeth is a fleshy substance, shaped like a tongue. After the mouth comes a short oesophagus, and then a membranous stomach attached to the oesophagus, and at the orifice of the stomach are three teeth, two facing one another and a third standing by itself [5] underneath. Coming off obliquely from the stomach is a gut, simple and of equal thickness throughout the entire length of the body until it reaches the anal vent.
These are all common properties of the crayfish, the carid, and the crab; for the crab too has two teeth.7 [10]
Again, the crayfish has a duct attached all the way from the chest to the anal vent; and this duct serves as the ovary in the female, and as the seminal duct in the male. This passage is attached to the concave surface of the flesh in such a way that the flesh is in between; for the gut is related to the convexity and this duct to the [15] concavity, pretty much as is observed in quadrupeds. And the duct is identical in both the sexes; that is to say, the duct in both is thin and white, and charged with a sallow-coloured moisture, and is attached to the chest.
[20] These are the properties of the egg and of the convolutes in the carid as well.
The male differs from the female in regard to its flesh, in having in connexion with the chest two separate and distinct white substances, resembling in colour and conformation the tentacles of the cuttlefish, and they are convoluted like the ‘poppy’ [25] of the trumpet-shell. These organs have their starting-point in cotyledons which are situated under the hindmost feet; and hereabouts the flesh is red and blood-coloured, but is slippery to the touch and in so far unlike flesh. Off from the convolute8 organ at the chest branches another coil about as thick as twine; and [30] underneath there are two granular seminal bodies in juxtaposition with the gut. These are the organs of the male. The female has red-coloured eggs, which are adjacent to the stomach and to each side of the gut all along to the fleshy parts, being enveloped in a thin membrane.
Such are the parts, internal and external, of these animals.
[527b1] 3 · The inner parts of sanguineous animals happen to have specific designations; for these animals have in all cases the inner viscera, but this is not the case with the bloodless animals, but what they have in common with red-blooded animals is the stomach, the oesophagus, and the gut.9
[5] With regard to the crab, it has already been stated that it has claws and feet, and their position has been set forth; furthermore, for the most part they have the right claw bigger and stronger than the left. It has also been stated that in general the eyes of the crab look sideways. Further, the trunk of the crab’s body is single and [10] undivided, including its head10 and any other part it may possess. Some crabs have eyes placed sideways on the upper part, immediately under the back, and standing a long way apart, and some have their eyes in the centre and close together, like the crabs of Heracleotis and the maia. The mouth lies underneath the eyes, and inside it there are two teeth, as is the case with the crayfish, only that in the crab the teeth [15] are not rounded but long; and over the teeth are two lids, and in between them are structures such as the crayfish has beside its teeth. The crab takes in water by the mouth, using the lids as a strainer,11 and discharges the water by two passages above the mouth, closing by means of the lids the way by which it entered; and the two [20] passage-ways are just underneath the eyes. [When it has taken in water it closes its mouth by means of both lids, and ejects the water in the way above described.]12 Next after the teeth comes the oesophagus, very short, so short in fact that the stomach seems to come straightway after the mouth. Next after the oesophagus comes the stomach, which is bifurcated, to the centre of which is attached a simple [25] and delicate gut; and the gut
terminates outwards, at the lid, as has been previously stated. [Between the lids the crab has parts like those near the teeth in the crayfish.]13 Inside the trunk is a sallow juice and some few little bodies, long and white, and others spotted red. The male differs from the female in size and breadth, [30] and in respect of the lid; for this is larger in the female and stands out further, and is more hairy, as is the case also with the female in the crayfish.
So much, then, for the organs of the Crustacea.
4 · With the testaceans such as the land-snails and the sea-snails, and all the shellfish and also with the sea-urchin genus, the fleshy part, in such as have flesh, is [528a1] similarly situated to the fleshy part in the crustaceans; in other words, it is inside the animal, and the shell is outside, and there is no hard substance in the interior. As compared with one another the testaceans present many diversities, both in regard to their shells and to the flesh within. Some of them have no flesh at all, as the [5] sea-urchin; others have flesh, but it is inside and wholly hidden, except for the head, as in the land-snails, and the so-called cocalia, and, among sea animals, in the purple murex, the trumpet-shell, the sea-snail, and the spiral-shaped testaceans in [10] general. Of the rest, some are bivalved and some univalved; and by bivalves I mean such as are enclosed within two shells, and by univalved such as are enclosed within a single shell, and in these last the fleshy part is exposed, as in the case of the limpet. Of the bivalves, some can open out, like the scallop and the mussel; for all such [15] shells are grown together on one side and are separate on the other, so as to open and shut. Other bivalves are closed on both sides alike, like the razor-fish. Some testaceans there are, that are entirely enveloped in shell and expose no portion of their flesh outside, as the ascidians.
Again, in regard to the shells themselves, the testaceans present differences [20] when compared with one another. Some are smooth-shelled, like the razor-fish, the mussel, and some clams, viz. those which some call milk-shells, while others are rough-shelled, such as the pool-oyster, the pinna, and certain species of clam, and the trumpet-shells; and of these some are ribbed, such as the scallop and a certain [25] kind of clam, and some are devoid of ribs, as the pinna and another species of clam. Testaceans also differ from one another in regard to the thickness or thinness of their shell, both as regards the shell in its entirety and as regards specific parts of the shell, for instance, the lips; for some have thin-lipped shells, like the mussel, and others have thick-lipped shells, like the pool-oyster. Some also are capable of [30] motion, like the scallop, and indeed some aver that scallops can actually fly, owing to the circumstance that they often jump right out of the apparatus by means of which they are caught; others are incapable of motion and are attached fast to some external object, as is the case with the pinna. All the spiral-shaped testaceans can move and creep, and even the limpet relaxes its hold to go in quest of food. Common [528b1] to these and to all hard-shelled creatures is the smoothness of the inside of the shell. In the case of the univalves and the bivalves, the fleshy substance adheres to the shell so tenaciously that it can only be removed by an effort; in the case of those that [5] are spiral-shaped, it is more loosely attached. And a peculiarity of all of these is the spiral twist of the shell in the part farthest away from the head; they are also furnished from birth with an operculum. And, further, all spiral-shaped testaceans have their shells on the right-hand side, and move not in the direction of the spire, [10] but the opposite way.14 Such are the diversities observed in the external parts of these animals.
The internal structure is almost the same in all these creatures, and in the spiral-shaped ones especially; for it is in size that these latter differ from one another, and in excess or defect of their characteristics. And there is not much [15] difference between most of the univalves and bivalves; but while they differ from one another but slightly, they differ considerably from such as are incapable of motion. And this will be illustrated more satisfactorily hereafter.
The spiral-shaped testaceans are all similarly constructed, but differ from one another, as has been said, in the way of excess or defect (for the larger species have [20] larger and more conspicuous parts, and the smaller have smaller and less conspicuous), and, furthermore, in relative hardness or softness, and in other such properties. All of them have the flesh that extrudes from the mouth of the shell, hard and stiff; some more, and some less. From the middle of this protrudes the head and two horns, and these horns are large in the large species, but exceedingly [25] minute in the smaller ones. The head protrudes from them all in the same way; and, if the animal be alarmed, the head draws in again. Some of these creatures have a mouth and teeth, as the snail; teeth sharp, and small, and delicate. They have also a proboscis just like that of the fly; and the proboscis is tongue-shaped. The [30] trumpet-shell and the purple murex have this organ firm and solid; and just as the horse-fly and the gadfly can pierce the skin of a quadruped, so is this proboscis proportionately stronger in these testaceans; for they bore right through the shells [529a1] of their prey. The stomach follows close upon the mouth, and this organ in the snail resembles a bird’s crop. Underneath come two white firm formations, like breasts; and similar formations are found in the cuttlefish also, only that they are of a firmer consistency in the cuttle-fish. After the stomach comes an oesophagus, simple and [5] long, extending to the poppy, which is in the innermost recess of the shell. These are clear in the case of the purple murex and the trumpet-shell, within the whorl of the shell. What comes next to the oesophagus is the gut; in fact, the gut is continuous with the oesophagus,15 and runs its whole length uncomplicated to the [10] outlet of the residuum. The gut has its point of origin in the region of the coil of the poppy, and is wider hereabouts [for the poppy is for the most part a sort of excretion in all testaceans];16 it then takes a bend and runs up again towards the fleshy part, and terminates by the side of the head, where the animal discharges its residuum; [15] and this holds good in the case of all spiral-shaped testaceans, whether terrestrial or marine. From the stomach there is drawn in a parallel direction with the oesophagus, in the larger snails, a long white duct enveloped in a membrane, resembling in colour the breast-like formations higher up; and in it are nicks, as in [20] the egg-mass of the crayfish, except that it is white in colour whereas the egg is red. This formation has no outlet nor duct, but is enveloped in a thin membrane with a narrow cavity in its interior. And from the gut downward extend black and rough formations, in close connexion, something like the formations in the tortoise, only not so black. Marine snails, also, have these formations, and the white ones, only that the formations are smaller in the smaller species. [25]
The univalves and bivalves are in some respects similar in construction, and in some respects dissimilar, to the spiral testaceans. They all have a head and horns, and a mouth, and the organ resembling a tongue; but these organs, in the smaller species, are indiscernible owing to the minuteness of these animals, and some are indiscernible even when the animals are dead or motionless. They all have the poppy, but not all in the same place, nor of equal size, nor similarly open to [30] observation; thus, the limpets have this organ deep down in the bottom of the shell, and the bivalves at the hinge connecting the two valves. They also have in all cases the hairy growths in a circular form, as in the scallops. And, with regard to the [529b1] so-called egg, in those that have it, when they have it, it is situated in one of the semi-circles of the periphery, as is the case with the white formation in the snail; for this white formation in the snail corresponds to the so-called egg. But all these parts, as has been stated, are clear in the larger species, while in the small ones they are [5] almost or altogether indiscernible. Hence they are most plainly visible in the large scallops; and these are the bivalves that have one valve flat-shaped, like the lid of a pot. The outlet of the excretion is in sea-creatures17 on one side; for there is a passage whereby the excretion passes out. [And the poppy, as has been stated, is an [10] excretion in all these animals—an excretion e
nveloped in a membrane.]18 The so-called egg has no outlet in any of these creatures, but is merely an excrescence in the fleshy mass; and it is not situated in the same region with the gut, but the egg is situated on the right-hand side, and the gut on the left. Such are the relations of the anal vent in most of these animals; but in the case of the wild limpet (called by some [15] the sea-ear), the residuum issues beneath the shell; for the shell is perforated. In this particular limpet the stomach is seen coming after the mouth, and the egg-shaped formations are discernible. But for the relative positions of these parts you are referred to the Anatomies.
The so-called hermit crab is in a way intermediate between the crustaceans [20] and the testaceans. In its nature it resembles the crayfish kind, and it is born simple of itself, but by its habit of introducing itself into a shell and living there it resembles the testaceans, and so appears to partake of the characters of both kinds. In shape, to put it simply, it resembles a spider, only that the part below the head and thorax [25] is larger in this creature than in the spider. It has two thin red horns, and underneath these horns two long eyes, not retreating inwards, nor turning sideways like the eyes of the crab, but protruding straight out; and underneath these eyes the mouth, and round about the mouth several hair-like growths, and next after these [30] two bifurcate legs, whereby it draws in objects towards itself, and two other legs on either side, and a third small pair. All below the thorax is soft, and when opened is found to be sallow-coloured within. From the mouth there runs a single passage [530a1] right on to the stomach, but the passage for the excretions is not discernible. The legs and the thorax are hard, but not so hard as those of the crab. It does not adhere [5] to its shell like the purple murex and the trumpet-shell, but can easily be loosened. It is longer when found in spiral shells than when found in the shell of the neritae.
The Complete Works of Aristotle Page 146
