BIOLOGY OF BIKINI ATOLL — SCHULTZ 305 



Emota^ when adult and sexually mature was 15 millimeters or five- 

 eighths of an inch long. This contrasts sharply with a 10-foot wide 

 nianta ray weighing about 700 pounds, taken in Enyu passage. The 

 largest lish, however, was caught by the commercial fishermen at 

 Bikini in over 40 feet of water. It was a tiger shark measurhig 13 

 feet 11 inches long, with an estimated weight of considerably over 

 half a ton. 



Living in the branching polyps of the coral Acro'pora^ was the little 

 yellowish goby, Gobiodon citHnus, which had during July and August 

 prepared a nest and laid eggs in it, Gobiodon cleared off a small 

 area, three-fourths of an inch by 2 inches long, at the base of a coral 

 branch arising near the center of the colony. On this carefully pre- 

 pared spot, a thin growth of green, purplish, or brownish-colored 

 algae occurred. 



Acropora responded to the presence of Gobiodon and formed a 

 slightly raised rim around the nesting area. This goby, only about 

 an inch long, then deposited a small cluster of eggs in the shallow 

 depression and both parents remained to protect their home. Each 

 Qgg was attached to a gelatinous substratum by a short adhesive stalk 

 with the head of the embryo on the opposite end. Among these eggs, 

 numbering 100 to 200, was a fine, branching, filamentous red alga. 

 The oblong eggs were close together but not crowded. 



Another remarkable association between a fish and an invertebrate 

 host occurred in this same habitat. On the lagoon floor in a few feet 

 of water down to depths of 20 feet or more lives a globular starfish, 

 Culcita Twvaeguinae^ that reaches the size of a man's head. We found 

 in its body cavity, in about half of those investigated, a nearly trans- 

 parent 6- to 10-inch-long eel-like fish — the pearlfish, Carapiis. We 

 kept one of them in a jar of water, noticing the very slow rate of 

 respiration and its ability to live in sea water with a low amount of 

 dissolved oxygen. Because Campus was transparent, the circulation 

 of the blood was observed clearly. 



FLAT PAVEMENTLIKE AREAS 



The nearly flat pavementlike areas on the atoll reef are carpeted 

 with a layer of tiny f oraminifera and vinelike algal growth, forming 

 a mat 1 or 2 inches thick. West of Bikini Island, such a reef is trans- 

 versed with numerous "cracks" or shallow grooves only a few inches 

 deep. In other places there are vast areas incompletely drained 

 during low water, leaving shallow tidal pools only an inch or two 

 deep. In these occur a few species of blennies, gobies, and sometimes 

 a large number of the blackish sea cucumber. Whenever these de- 

 pressions retain about a foot of water, corals begin to grow and the 

 animal life increases. 



