Hopkins Marine Station Student Paper

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(full paper is archived in the Miller Library)

Title: Prevention of infanticide: Extra-embryonic chorion functions to protect eggs of tunicates and other marine invertebreates against digestion by the adult
Student Author(s): Levine, Marcie
Faculty Advisor(s): Epel, David
Pages: 28
Location: Final Papers Biology 175H
Date: June 1981
Keywords: ascidians
Abstract: Eggs from solitary and colonial tunicates were fed to adult Ascidia ceratodes and Ciona instestinalis. Those eggs which are normally spawned, A. ceratodes and C. intestinalis, were recovered unharmed from fecal pellets and embryonic development observed to continue. Dechorionated eggs and viable tadpoles, however, were digested. Furthermore, eggs which are invariable brooded, those of Clavelina huntsmani and Botryllus sp., were not recovered intact. Fertilized Stronglyocentrotus purpuratus eggs were also able to survive ingestion by the adult A. ceratodes. A correlation was noted between protease-insensitivity of the chorion and fertilization membrane and the resistance to digestion. It is suggested that the proteolytic insensitivty of the extra-embryonic investments serves to protect eggs normally spawned from digestion by filter-feeding adult tunicates.