ZOOLOGICAL SOCIETY BULLETIN 



1463 



Many fishermen plant cover : A fragment of 

 waterlogged wreckage or some large crumpled 

 sheets of iron that seem to offer protection are 

 placed near the feeding grounds. Lobsters find 

 these places of apparent safety while wandering 

 over the banks at night in search of food. To- 

 ward morning they take refuge beneath them. 

 The fisherman who has carefully taken bearings 

 can return to his lure when crayfish are not 

 available elsewhere and be sure of enough bait 

 if no one has found his plant. 



SOME BABIES OF THE SEA* 



Hoiv They Differ From Their Parents. 



By Ida M. Mellen 



THERE are no controversies among families 

 that live in the ocean as to whom the baby 

 resembles. In truths many little creatures 

 born in the sea are as unlike their parents as 

 though they belonged in a different genus, and it 

 is only by carefully studying their complete de- 

 velopment that we are able to unravel the story 

 of the remarkable transformations through 

 which they are destined to pass after emerging 

 from the egg and before reaching maturity. 

 "Taking all shapes from Mah to Mahi," they 

 are perhaps free-swimming and pelagic when 

 very young, and attached to rocks or other ob- 

 jects when older; perhaps they have a shell in 

 their early days and none when fully grown, 

 or vice versa. 



The baby molluscs are at one period known 

 as veligers, the starfishes as bipinnaria, and 

 the little annelids as trochospheres ; while some 

 of the Crustacea, passing through several moults, 

 are characterized by a different name for each 

 stage of their growth, as nauplius, metanau- 

 plius, zoaea, megalops, and so forth. 



No one who has attempted to dislodge a bar- 

 nacle and observed its apparent immovability, 

 would suppose that when this stony little crus- 

 tacean was a baby, it skipped about in the 

 ocean as briskly as a flea, or that at one stage 

 it possessed, like the Greek Polyphemus, a 

 single median eye, later two eyes, and a sharp 

 little spike of a tail. After a time, true to the 

 history of countless generations of its race, the 

 young barnacle experiences an overpowering in- 

 stinct to settle down. Then fixing itself firmly, 



*The illustrations accompanying this article have 

 been equalized in size for the sake of clearness. It 

 will be understood that the young animals are mi- 

 nute, — in some instances, as in the Nauplius of t-he 

 Barnacle, microscopic; while the adults range in 

 size from the Nudibranch mollusc three-eighths of an 

 inch in length, to the toadfish about a foot long. 



Left: NAUPLIUS STAGE OF BARNACLE. Eiffht: ADULT 

 BARNACLE. 



head foremost, to a chosen spot, it undergoes its 

 last change, assuming the form with which we 

 are most familiar. The small legs no longer help 

 it to swim about in search of meals, but, modi- 

 fied into "cirri" or "gill filaments," are now 

 protruded from the shell and sweep the food 

 inside. 



Some of the hydroid polypes and their young 

 differ so greatly from each other in behavior, 

 if not in structure, that, were a winter, squash 

 to open and produce a rabbit, or a crab-apple 

 burst and send forth a humming bird, it could 

 hardly astonish us more than to behold minute, 

 actively swimming medusae or jelly-fishes is- 

 suing from what at first glance appears to be 

 only the stalk of a plant. 



Hydroid methods of reproduction are diversi- 

 fied, but in some species these exquisite, trans- 

 parent little jelh^-fishes spring from the sta- 

 tionary polypes and seek the surface of the sea, 

 where, during their transitory existence, they 

 lightly abandon themselves to the will of the 

 waves, exhibiting, in every rhythmic movement, 

 "a grace beyond the reach of art." 



All hydroids do not produce jelly-fishes, nor 

 do all jelly-fishes arise from Iwdroids ; but the 

 eggs of those jelly-fishes which are born of hy- 

 droid polypes give rise to polypes, and these in 

 turn produce jelly-fishes; so that, in this proc- 

 ess of reproduction, known as "alteration of 

 generations," parent and child are wholly dis- 

 similar, while grandparent and grandchild are 

 precisely alike. 



As a rule the word mollusc creates in our 

 minds the picture of an animal in the possession 

 of a hard shell, yet there must be exceptions 

 to rules, even among molluscs, some of which 

 are never provided with a visible shell, while 

 others have one only in the early stages of their 

 growth. It is evident that a shell frequently 

 serves as a life-saver for the tender creature 

 which is able to stow itself within the impene- 

 trable valves secure from its enemies, yet one 



