On examining the crustacean world, we find that it has established its head-quarters in the tropical zone. There a multitude of wondrous types unknown to the colder regions of the globe attract the attention of the naturalist: the transparent phyllosomas, not thicker than the thinnest wafer, and the strange sword-tails, whose body is covered by a double shield, and terminates in a long horny process, used by the Malays to point their arrows. The crabs and lobsters of the tropical waters are not only more numerous than in our colder seas, but they attain a far greater size than those of the temperate regions of the globe.
The decapod crustaceans (cray-fish) which inhabit our rivers and brooks, are long-tailed like the lobster, but in the torrid zone the river species all belong to the order of the short-tailed crabs, the most perfect and highly developed of the class. Some species even entirely forsake the water and spend their days on shore, not only on the beach, but far inland on the hills. When the season for spawning arrives, large numbers of these land-crabs set out from their mountainous abodes, marching in a direct line to the sea-shore, for the purpose of depositing their eggs, which are attached to the lower surface of the abdomen and are washed off by the surf. This done, they recommence their toilsome march towards their upland retreats, setting out after nightfall and steadily advancing until the dawn warns them to seek concealment in the inequalities of the ground or among any kind of rubbish, where they lie, until the stars again invite them to pursue their course. On their seaward journey, which they prosecute so eagerly that they suffer no opposition to deter them from their purpose, they are in full vigour and fine condition, and this is the time when they are caught in great numbers for the table, their flesh being held in high estimation; but on returning from the coast they are exhausted and unfit for use.
LAND CRAB.
Wherever the West Indian Land Crabs make their home, their burrows are as thickly sown as those of a rabbit warren. Concealed during the greater part of the day in these subterranean abodes, they come out at night to feed, but are always ready to scuttle back at the least alarm. Should, however, their retreat be intercepted they show a bold front to the enemy, seizing him with one of their long claws, and then shaking off the limb at its junction with the body. As the claw retains its tension for some little time after this voluntary separation, the effect is the same as if the creature were still actively biting, and while the enemy’s attention is engaged with these troublesome pincers, the crab takes the opportunity to conceal itself in some crevice. As is the case with all crustaceans, a new limb soon sprouts out and repairs the loss of the discarded member.
A singular species of land decapod, called the Fighting Crab from its bellicose propensities, possesses one large and one very little claw, which gives it a very strange and ridiculous appearance, particularly when, running along at full speed, it holds the large claw in the air, and nods it continually, as beckoning to its pursuer.
The molluscs are no less profusely scattered over the tropical seas and coasts than the higher organised crustaceans. There we find those mighty cephalopods, whose long fleshy processes, as thick as a man’s thigh, are able, it is said, to seize the fisherman in his boat and drag him into the sea; and there is the abode of the tridacna, whose colossal valves, measuring five feet across, attain a weight of five hundred pounds, and serve both as receptacles for holy water in Catholic churches and to collect the rain in the South Sea Islands.
The rarest and most beautiful of shells, the royal Spondylus, the Carinaria vitrea, the Scalaria pretiosa, the Cypræa aurora, and a host of Volutes, Harps, Marginelles, Cones, &c., of the most exquisite colouring, are all inhabitants of the warmer waters; and the most costly gift of the sea, the oriental pearl, is the produce of a mollusc which is found scattered over many parts of the Indian and Pacific Oceans.
On descending still lower in the scale of marine life, we find the jelly-fish disporting in the tropical waves in hosts as brilliant as the skies. Some are formed like a mushroom, others assume the shape of a belt or girdle; others are globular, while some are circular, flat, or bell-shaped; and others again resemble a bunch of berries. In colour, perhaps the most delicate is the lovely Velella, with its pellucid crest, its green transparent body and fringe of purple tentacles; but it is surpassed in size and gorgeousness by the Physalia, or ‘Portuguese man-of-war,’ whose large air-sack, with its splendid vertical comb, shines in every shade of purple and azure. The greatest marvels of the tropical ocean are, however, beyond comparison, the wondrous buildings of the Lithophytes, or stone polyps, the reefs and coral islands. Here we see them forming vast barriers which fringe the shores for hundreds and hundreds of miles; there they rise in circular atolls over the blue waves, like bridal rings dropped from the heavens upon the surface of the seas. All is wonderful in these amazing constructions—their puny architects, the lagoons they encircle, the power with which they resist the most furious breakers, the little world of plants drifted over the waters, which ultimately covers them with a verdant crown, and invites man to settle on these gardens of the ocean. There the tall cocoa-palm rocks its feathered crest in the breeze, affording both shade and fruit to the islander, and there the sea-bird finds a resting-place after its wide flight over the deserts of the equatorial sea.