1464 



ZOOLOGICAL SOCIETY BULLETIN 



who watches certain 

 snails must be im- 

 pressed by the awk- 

 wardness of their 

 movements and the in- 

 convenience they so 

 manifestly experience 

 in being compelled to 

 carry a heavy house 

 wherever they go. 



Left: JELLYFISH (MEDUSA OF OBELIA). Left: HYDROID 

 POLYPE (OBELIA). 



A few of the molluscs have succeeded in elim- 

 inating this clumsy burden which Nature orig- 

 inally imposed with such good intentions, by 

 dropping off the shell before arriving at matur- 

 ity. These — the nudibranch or naked mol- 

 luscs — when young, bear a close likeness to com- 

 mon snails, the shells being even more ponder- 

 ous and obstructive, if possible, and requiring 

 great pulling along, like an unwilling dog on 

 a leash. The baby mollusc twitches its shell 

 this way and that, as if petulantly exclaiming, 

 "I'll be glad when I get rid of you." 



"Body and soul, like peevish man and wife. 

 Together can't agree, and yet are loth to 

 part." 



This mollusc parts with its shell after a time, 

 and spends the remainder of its days gliding un- 

 encumbered over the rocks and vegetation of the 

 sea. 



Another mollusc, the squid — which is attain- 

 ing some economic importance and is said to be 

 very good to eat pickled, or fried in olive 

 oil and served with lemon juice — permanentlj^ 

 did away with most of its shell so many centu- 

 ries ago that the only remnant of that organ 

 now discoverable, even in the very young mol- 

 lusc, is a delicate process resembling a quill pen, 

 lying beneath the skin and running nearly the 

 entire length of the body. 



A squid just hatched reveals more of the 

 characteristics of its species than many other 

 sea babies. The beautiful eyes, and the typi- 

 cal "pen and ink" are noticeable, the ink sac 

 and siphon pore through which the black fluid 

 will be squirted to confuse its enemies, being 

 fairly well developed when it leaves the ^gg. 



The round little body will become elongated 

 and the tail fins will move forward consider- 



ably and alter their shape. The yolk sac which 

 is half as large as the body itself, will be grad- 

 ually absorbed, and the ten small arms grow 

 longer and stronger till it learns to catch its 

 prey. 



Among the most interesting of all living 

 things are the marine worms, many of which, 

 busily kneading and churning the sea-sand, per- 

 form for the ocean bed that same useful func- 

 tion which their congener, the earthworm, per- 

 forms for the dry land. 



Some dwell in burrows of sand, while others 

 build houses of bits of gravel and shell, or se- 

 crete a limestone tube of an appropriate size 

 to contain and protect their soft, lithe bodies. 

 In many forms the young, while passing through 

 the so-called trochosphere stage, swim on the 

 sea's surface, thus seeing something of the top 

 of the ocean with their one little eye before set- 

 tling on the bottom of it and practicing the art 

 of tailoring a calcareous jacket. 



The trochosphere baby of four days looks 

 quite unlike his parents, but in another week 

 queer changes will come over him "from top to 

 toe" and almost before he knows what is hap- 

 pening, he will And himself — a worm. 



It would be difficult to discover in the ocean 

 anything of more fantastic design than a crus- 

 tacean in the zoaea stage of its development. 

 The large, saucerlike eyes and marvelously long, 

 conspicuous spines, immediately distinguish 

 most zoaeas from every other living creature. 

 Many of the crabs and 

 shrimps are born as 

 zoaeas and look per- 

 plexingly alike in this 

 and their next stage — 

 megalops. Numerous 

 moults are required to 

 bring out the definite 

 characters that deter- 

 mine the species. 



The tiny zoaea is re- 

 markable in appear- 

 ing to consist for the 

 most part of head; 

 but it will be observed, 



Left: NUDIBRANCH MOLLUSC {MONTAGUA) WEEK 

 OLD. Bight: ADULT. 



