FOOD, REPRODUCTION AND ORGANIC CONSTITUTION OF THE COMMON ANTARCTIC ECHINOID STERECHINUS NEUMAYERI (MEISSNER)

¹ Department of Biological Sciences, Stanford University, Stanford, California 94305

1. The common Antarctic echinoid Sterechinus neumayeri (Meissner) feeds mostly on diatoms, although such things as seal feces are also used for food when available.

2. Specimens of S. neumayeri in McMurdo Sound have discrete reproductive periodicities as do most echinoids in other parts of the world. Oocyte growth begins in the summer between November and May, the oocytes take from 18 to 24 months to reach maturity after beginning growth, and spawning occurs sometime in the winter or spring between May and December. The embryos presumably develop slowly into demersal echinopluteus larvae in the summer when plant food is available.

3. Nutrients seem to be accumulated in the nutritive phagocytes of the gonads during the summer when phytoproduction occurs, and the gonads increase in size during this period. These nutrients are probably utilized during the winter to maintain a relatively constant rate of gametogenesis.

4. The lipid, carbohydrate, protein and total nitrogen levels in the gonads, test, gut and gut contents of S. neumayeri are similar to those of other echinoids, although the carbohydrate content in the gonads is generally higher than in most other echinoid gonads that have been studied.

5. Differences among the populations of S. neumayeri in McMurdo Sound support an earlier suggestion that food conditions are better at Cape Evans and farther north than they are south of Cape Evans.