The reproduction of some littoral molluscs from Macquarie Island (Sub-Antarctic)

The reproduction of 9 species of littoral molluscs from the sub-Antarctic Macquarie Island was examined. The mode of larval development is reported for all species, and the reproductive patterns for 7 are described from collections taken monthly over a period of 1 year. Two species release gametes for external fertilization, whereas the other 7 have non-pelagic development via brooding or the laying of egg cases; some of these findings were deducted from examination of gonads rather than by direct observation. Features of reproduction important in any correlation between a littoral animal's reproduction and its habitat are discussed, and relationships between pelagic and non-pelagic development of the Macquarie molluscs and (a) distribution in the local environment and (b) habitat are drawn. The widely recognised correlation between species having a non-pelagic development and small number and large size of eggs is considered as a method for predicting the type of larval development (in terms of pelagic versus non-pelagic) from an examination of the ovary. It is suggested that further data on modes of development could be obtained from specimens of marine invertebrates collected throughout southern latitudes and that such data would enhance zoogeographical interpretations.