Embryonic development of cephalopods at low temperatures

Abstract

No information is available on the embryonic development of Southern Ocean cephalopods. Estimations of developmental times can only be made by extrapolation using data from other geographical areas. Based on known relationships between environmental temperature and embryonic development time, it appears that below 5°C even the smallest squid eggs measuring 0.6–1.0 mm in diameter need one to two months to develop to hatching. At c. 2°C, the embryonic development of these small eggs would probably cover between three and five months. Very large octopod eggs are known to develop over time spans of at least one year. Protection of the developing embryos either by long-lasting capsules laid at appropriate spawning sites, or by active ‘brooding’ (incirrate octopods) is required for embryonic survival and hatching success. The physiological conditions controlling the onset of hatching at very low temperatures are unknown; postponement of hatching appears to be common in cold waters.