The egg finger of Loligo has been the object of recent research at the MBL. Researchers are studying the bacteria that inhabit the outer layers of the capsule. There are several different types of bacteria that inhabit these layers and they may have a role in the development of the embryos within. The yellowish hue of the egg capsule, for example, is caused by carotenoids that are produced by these bacteria.

Another mystery is how the eggs are protected from predation. A large mass of protein-rich eggs should be an appetizing target for a wide range of hungry animals ranging from shrimp and crabs to fish and snails. Yet the thousands of eggs remain uneaten.

The photograph shows part of the egg capsule housing several hundred developing embryos. Click the photograph for a closer look. The embryos are each encapsulated in a chorion that is in turn surrounded by a gelatinous material housed in the egg capsule. The egg yolk is absorbed by the developing embryo.

The development of Loligo was first described in 1880 by W.K. Brooks in a paper to the Boston Society of Natural History. He obtained eggs and embryos from the Chesapeake Bay and began observing and drawing the developing young. This image is taken from that manuscript and shows a pre-hatch Loligo attached to its yolk sac. Clicking the image will show a more detailed view.

McGowan, J.A., 1954, Observation on the sexual behavior and spawning of the squid Loligo opalescens at La Jolla, California, California Fish. Game 40:47-54