Embryonic development, feeding and intracapsular oxygen availability in Trophon geversianus (Gastropoda: Muricidae)

MARIANO CUMPLIDO; PAULA PAPPALARDO; MIRIAM FERNÁNDEZ; ANDRÉS AVERBUJ

JOURNAL OF MOLLUSCAN STUDIES

OXFORD UNIV PRESS

Lugar: Oxford; Año: 2011 vol. 77 p. 429 - 436

0260-1230

Large-scale patterns of encapsulated embryo development and causal factors determining developmental success in the marine environment have been relevant issues of research for decades. We studied the embryonic development and intracapsular oxygen availability of Trophon geversianus in egg capsules fromnorthern Patagonia (Golfo Nuevo, Argentina). The intracapsular embryonic development had a mean duration of 112 days (at 12?148C). The initial number of eggs per capsule was 197 (mean diameter 270 mm), but on average only four embryos per capsule reached the juvenile stage. Embryos fed on nurse eggs (which disintegrated spontaneously 48 h after oviposition). The sequence of ntracapsular developmental stages was recorded from egg to hatching occurred at the crawling stage (mean shell length 2.8 mm). Maximum growth rate was observed at the ?veliger? stage, while nurse eggs were consumed. A decrease in embryo number was observed between prehatching and hatching. Cannibalism was recorded in an egg capsule containing a prehatching embryo, which showed signs of shell drilling by the accessory boring organ. Intracapsular oxygen availability decreased from 90% during the cleavage stage to 45% of air saturation in the final stages of development (at 138C). Abnormal embryos were recognized in egg capsules, probably associated with food competition or oxygen limitation.