Mating Strategies in Giant Cuttlefish
Sepia apama, also known as the giant cuttlefish, is a species of cuttlefish that are sexually dimorphic. Male Sepia apama are equipped with longer arms than females that are lined with webbing off the ventral margins (M. Norman et. al. 1999). Mating among Sepia apama involves the males using elaborate color displays in the form of stripes pulsing across the dorsal mantle and across the webbing on their arms. The females, in turn, watch to see which male’s color display she fancies most (M. Norman et. al. 1999). Sepia apama copulation occurs by the male transferring sperm packets, called spermatangia, to a pouch located below the beak of the female that are internal sperm-storing organs called receptacles (M. Naud et. al. 2005). During this process of copulation, the female, which is polyandrous, displays patterns of dark blotches on their pale bodies (M. Naud et. al. 2005). Once the transfer of sperm is complete, the female lays her eggs one by one while attaching each one individually to the undersides of rocks and ledges using a gelatinous stalk before the eggs are fertilized by being passed over the sperm pouch located below the mouth. During this entire process, the male remains close by to ensure no other suitors try to mate with the female (M. Norman et. al. 1999). The eggs of Sepia apama are larger than average aquatic eggs and are lemon shaped. The eggs consist of having a jelly-like outer layer, the chorion membrane, perivitelline fluid, and vitelline membrane that encloses the yolk and embryo (E. Cronin and R. Seymour 2000).
The female Sepia apama can store sperm for several different males prior to fertilization, which is why males watch the female closely to ensure she doesn’t mate with another male. Female decapod cephalopods, consisting of cuttlefish and squid, have either a single or double sperm receptacle (M. Naud and J. Havenhand, 2006). It has been found that females can use any of the...