Nature. A Strange Fish.

Waikato Times, Volume XXIV, Issue 1976, 7 March 1885, Page 2 (Supplement)

Nature. A Strange Fish.

Suvniurj years ago, in walkiDg along tho halfsubmerged fringing reef of the Tortugcis group of ißlandn, my attention was attracted by the numbers of f^reafr, black, worm like creatures that weie strewn over the bottom ju«t within the breakers, where the water was smooth. They were Jlolothtiinni, or sea-cucumbers. Wißbing to secure a large ppecimen, I hauled my bout over among them, and Boon had one, more than a foot in length in the glass jar, or portable aquarium, carried for that purpose,

Another was lifted fiom its Handy bed for examination, and a ourioua creature it was. It seomed like a great, grotesque .aterpillai, made out of leather and filled with water, as the handling caused it to eject two streams of water with conquerable force. After placing it upon the seat of the, boat, we found that the croiture had ejected all iti interior oigana — actually thrown them off. Inir would have been a grievous calamity to almost any animal exc°pt tho sea-eucuraber ; but, curiously enough, they have t. c faculty of reproducing let p&r!.s to a wonderful dp^ree, ami if plucprt beck in the water would aoon pvovide themselves with an tntirely new set. If wo should follow up our investigations of the anatomy of the* pea cucumber we should find that it breathes by what is called a wrtter-va°cular Bystem. In the star-fishes a haid red spot is seen upon the upper surface, punctured with minute holes. Through tins water is strained and taknn in, pspsing out into the arm«, and filling the oac-likefeet. In tho fcea-cacumber there is a similar arlangement, only the madreporic plate, as the pink sieve is called, is on the inmde. Though certainly not gourmands, starvation affects some of them in a remarkable way. Thus, if kept for a long time without fond, a ring -will be formed about the tail that grow t deeper and deeper, until, finally, the piece diops off. In a short time another ring appears aud another piece is sacrificed — a most remarkable operation, you will aay, but quite ingenious when wi understand it. The animal in merely retrenching, and, as the food Huprly becomes smaller and smaller, portions of i js body are thrown off, so that there will not be so much to feed, until, at laat, the sea-cucumber will sacrifice its entire body to save the mouth or head, and finally this dies, certainly after a heroic struggle. But while we have been looking at other sea-cucumbers, what has happened to the one we placed in tho glass jar? Being a large animal, it has soon exhausted tho air in the water, and is now endeavoring to get out, twisting iti body deliberately about to show its da-comfort, for you mast remember that the sea-cucirnber and all other water animals require air just as much as ourselves. For several moments the sea cucumber writhed about in its lazy faßhion, when, all at OD"e, out of one end I saw peeping & curious, delicate head. A moment later, it was still further out — a transparent shining fish, and soon, with a convulsive wriggle, it freed itself from its strange prison and swam about a moment ; then settled to the bottom. Its body was so delicate and transparent that print could almost be read through it, and a specimen that I have before me now, though shrunk and hardened in alcohol for several year 3, is still almost like glass. But how did the fish get in the sea encumber? you will ask. This was, at first, a puzzle, and to ascertain whether it was aocidental or not, we collected a large number of the cucumbers (Holothuria /loridiana) t tind in nearly every case, as soon as the animal bad exhausted the air in our aquarium, the filvery, eel like Ficratfer — for this is tho fish's name— would come wriggling out, swim about for a moment as if dazzled and bewildered, and then sink to the bottom and die. It was evident that tha fish was not eaten by the Holothurian, and equally plain that tho fish was not adapted for the outnido world. Hence, we assumed that the Fieraafer was a boarder in the cucumber, and such is reaily the case. But, though I made many experiments, the fish could never be induced to return to its home, though freshly aerated water was constantly supplied. The conclusion that seemed most tenable wah that the fish never left the holothurian ; but this was highly improbable, and so the puzzle remained until it was solved by the curator of the great aquarium at Naples, Italy. He found that his sea-cucumbers were also inhabited by a Ficrasfcr, and by oarofully watching them, ho saw the fishes come, out and return. In the large tank, tho fishes ventured out, swam round, probably fed, and finally returned ; and here is the most remarkable part of it. Instead of returning head first, aa you would naturally expect, the Firrasfer slipped, not its head, but the tip of its tail into the orifice. In a moment, the sea-cuoumber relaxed to draw in water, and the cunning fish slipped in an incb, then rested ; another relaxation by tb.9 cucumber, and another inch gained, and bo on, until, to the amazement of the Italian naturalist, the tierasfcr disappeared, tail first, within the very accommodating animal. Tho Ficrasfe*, then, is a boarder in the seacucumber, a tenant that not only lives upon its ho i -t without pay, but does not hesitate to attack it when hungry. This has been proved by Prof. Semper, who found pieces of tho water-lung of the living hotel in the stomach of the boarder ; but, as we have seen, the former is able to ipproduco lost parta, and probably does not Buffer. Tho boarder also undoubtedly feedi upon food taken in by its host. — Prof. Holden in Golden Days.