Meeting Abstract

49.10  Jan. 6  Egg mass physiology: Comparative morphology and physiology of experimental and natural invertebrate egg masses from temperate and Antarctic sites MORAN, A.L.**; WOODS, H.A.; Clemson University, Clemson, SC; University of Montana, Missoula moran@clemson.edu

Embryos of many marine invertebrates are encased in gelatinous masses for part or all of development. Both experimental evidence and physiological models suggest that egg masses of a given morphology (size, shape, and density of embryos) perform differently at warm compared to cold temperatures. In particular, because the metabolic oxygen demand of ectothermic embryos decreases with decreasing temperature, egg mass morphologies that would result in severe internal hypoxia in warm environments may be �permissible� in extreme cold environments. Our biophysical models predict that at a given embryo density, masses at 0 degrees C can have diameters 6-fold greater than masses at 20 degrees C; likewise, for a given size, Antarctic masses can have higher densities of embryos, more globular morphologies, and thicker protective layers than temperate masses. We test these hypotheses in two ways. First, we constructed low-temperature artificial egg masses using embryos of Antarctic invertebrates, in which we experimentally manipulated size, shape, and embryo density. Second, we compared the morphologies and oxygen distributions in egg masses of temperate nudibranchs versus their Antarctic relatives.