Market Squid, Part II.

Development continues. The chorion was removed from some of the eggs to better observe embryo. The siphon is now nearly formed, and soon the edges will fuse medially to form a hollow tube. Two rows of suckers are visible on the lengthening tentacles. The optic ganglions are visible in the eye stalks behind the eyes themselves. The newly formed brachial hearts and developed gills can be seen within the mantle.

The squid has three hearts—two brachial hearts which pump blood through the gills and a systemic heart which moves blood through the rest of the body. Notice the rhythmic pumping of the two brachial hearts in the videos.

[video 1] [video 2]

The squid has developed chromataphores, which are the red-orange pigment spots on the mantle and head of the embryo. The embryo is more active now and frequently shifts within the egg. It has also started to contract its membrane.

[video]

Comparison of early and later stage embryos. Notice the expansion of the chorion in the older embryo. It is possible that the chorion expands because of osmosis due to the buildup of metabolic waste within the egg.

Fields, William Gordon. The structure, development, food relations, reproduction and life history of the squid Loligo opalescens Berry. Diss. Department of Biological Sciences, Stanford University., 1962.

-Jacqueline Brockhurst