Plate 16.
P. H. GOSSE, del. LEIGHTON, BROS.
SEA-HARE.
SEA-HARE.
The animal is one of the Sea-slugs, allied, not remotely, to the Doris and the lovely Eolis, which occupied our attention some time ago. The order to which it belongs is, however, distinguished from them by having the breathing organs covered. In our Sea-hare these take the form of complicated leaflets, which are placed upon the middle of the back, and are protected by a broad plate of shell, somewhat like a watch-glass of irregular outline, very thin and transparent, and very brittle when dry. During life, this shelly plate is imbedded in the substance of the skin of the back, a thin layer of which clothes it; so thin that it can be very readily seen and felt notwithstanding. The mantle is much developed, forming two great irregular wing-like lobes, which stand up on each side of the body, and at pleasure either arch over the gill-shield, or are depressed, and widely expose it. It is reported that these mantle-lobes are capable of being used as swimming-fins, by their undulations; but I doubt the correctness of the observation.
When full-grown, our Sea-hare is three inches in length, and upwards of an inch high. Its body is of a slimy, fleshy, slug-like texture, varying much in colour; sometimes being dark olive-green, sometimes red-brown, sometimes deep purple, occasionally clouded with blue: sometimes the hue is uniform; at others, it is varied by light dots, or handsomely marked with dark rings enclosing white areas. Its figure is extremely versatile; so that, when crawling, it scarcely exhibits the same outline for two minutes together.
See what has happened. On dropping one of the slimy beasts into this phial of clear sea-water, it immediately resented the incarceration by beginning to pour out from beneath the lobes of the mantle a thin stream of fluid of the most royal purple hue, which freely diffused itself through the water. And see! it is still copiously exuding; and the whole contents of the bottle are now fast becoming of so fine and rich a tinge, as already to veil the form of the animal. Attempts have been made to employ this secretion in the arts; but the hue is fleeting. According to Cuvier, it assumes in drying the beautiful deep hue of the flower known as the sweet scabious, and remains long unaltered by exposure to the air. The purple tint is readily transferred to spirit, when the animal is immersed in it; the tincture retains the colour for a while, but ultimately becomes of a deep clear port-wine tint. Linen, dyed with the fluid, soon fades to a dingy brown.
It is a curious coincidence that this mollusk possesses a more recondite analogy with herbivorous mammalia, than a fleeting resemblance of form. Professor Grant has shown that it has three stomachs, like the ruminants. First, a short narrow gullet dilates into a large membranous crop; a curved bag, which is generally filled with pieces of coarse sea-weed. This large crop or paunch occupies the right side of the body, and opens laterally into the middle stomach, which is the smallest of all, and performs the part of the gizzard. Its coats are thickened; and the interior callous lining is besat with firm horny processes, in the form of rhomboidal plates or molar teeth, which serve to compress the softened vegetable matter transmitted in small portions from the first stomach. The third cavity of this complex apparatus is placed on the left side of the body; its interior surface is studded with sharp, horny spines, resembling canine teeth, to pierce and subdivide the coarse food, and thus prepare it for the action of the gastric juice and other fluids accessory to digestion, which enter the stomach from adjacent organs.[67]
The complexity of this structure has reference to the coarseness of the materials on which the animal subsists; the leathery fronds of the olive sea-weeds, which slowly and with difficulty yield their nutritive elements to the digestive functions.
This great, flabby Sea-Slug has a mythic history full of wild romance. Our species has been often called depilans, because the fluid which exudes from it was said to have the power of causing the hair to fall from the human head which it touched; and the common species of Southern Europe retains the appellation in the records of science. The Mediterranean fishermen have so great a horror of it that no bribes will induce them to handle it willingly; and they tell strange stories of wounds being produced, limbs being mortified, and even death itself being caused, by accidental or foolhardy contact with the potent creature.
Bohadsch has given, on the authority of personal observation, a minutely circumstantial account, which it seems a hyper-scepticism to doubt. When removed from the sea, and placed in a vessel, there exuded a large quantity of a limpid and somewhat mucilaginous fluid, exhaling a sweetish, sickening, peculiar smell: but besides this, and distinct from its purple secretion, the Aplysia excreted also a milky liquor, formed in an internal conglobate gland, which seems to be analogous to the kidney of vertebrate animals. As often as he took the Aplysia from the vase of sea-water and placed it on a plate with the view of more narrowly examining its structure, the room was filled with a nauseous odour, compelling his wife and brother to leave the room, lest sickness and vomiting should follow. He himself could scarcely endure it, and during the examination had repeatedly to go out and breathe a purer air. His hands and cheeks swelled after handling the creature for any length of time, and as often as it ejaculated its milky secretion; but he is uncertain whether the swelling of the face proceeded from the halitus merely, or from his having accidentally touched it with the hand besmeared with the liquid: probably the latter was the real cause, for when he purposely applied some of it to his chin, some hairs fell from the part.[68]
We may add to this account, as being in a measure confirmatory of its probability, the statement of a perfectly dependable naturalist, Mr. Charles Darwin, that he found a species of Aplysia at St. Jago, one of the Cape Verd Isles, from which “an acrid secretion, which is spread over its body, causes a sharp stinging sensation, similar to that produced by the Physalia,[69] or Portuguese man-of-war.”[70] And yet I have myself freely handled Aplysiæ in health and vigour, both here and on the coast of Jamaica, without perceiving the slightest unpleasant sensation.