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. Invertebrates
The invertebrates were assayed becauseof their potentiality as food
for humans and for animals that might serve as food.
The giant clam,
longusta or spiny lobster, and coconut crab undoubtedly are eaten by the
natives.
Corals and sea cucumbers are considered chiefly because of their
abundance and role in the ecology of the atolis.
Radioactivity in Rongelap invertebrates declined from about 102 - 104
uc/kg on March 26, 1954 to approximately 107! - 10! uc/kg on October 2122, 1955, as shown in Tables 5 and 6 and Figures 5 - 10.
Levels of radio-
activity in October 1955 at Kabelle, Labaredj, and Rongelap Islands and at
Enibuk Island (Ailinginae Atoll) were, respectively, 3+, 6+, 2, and 1 uc/kg
of wet tissue.
Individual values for the October 1955 collections appear in
Appendix C.
Liver of the spider snail (Fig. 8) averaged highest in radioactivity through-
out the 1, 6-year period of study, being most closely approached early by the
hermit crab liver, which declined rapidly (Fig. 6) and at the end of the period,
by the slowly-declining coconut crab carapace (Fig. 5).
The low level of
activity of the basic coral organisms (Fig. 10) is of special interest.
Of the
tissues analyzed muscle had least activity, that of the giant clam in October
1955 being legs than 0.1 uc/kg (Fig. 7).
The low level of activity in the giant clams, Tridacna and Hippopus, presumably results from feeding upon plankton, which is also low.
In contrast,
the spider snail, Pterocera, with activity about 10 times that of the planktonUNIVERS Ty tn ryper en
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