Too much sex exhausts the promiscuous dumpling squid

The dumpling squid, also known as Euprymna tasmanica, are known for their promiscuous mating behavior – mating with as many partners as possible. These short-lived cephalopods can spend up to 3 hours copulating, when the males and females would appear to be “locked” together. Upon closer inspection, we realize that the male squid actually physically restrains the female to prevent her from moving during copulation.

After copulation, the male and female dumpling squid both suffer from reduced performance and swimming endurance and takes up to 30 minutes to recover. Given that males physically restrain females during copulation, it was naturally expected that males that a longer time to recover than female dumpling squids.

Statistical analysis from “Biology Letters”, however, proved otherwise. Both male and female dumpling squids take the same amount of time to recover post-copulation.

Males are weakened due to the vigorous activities they do: restraining the female, changing color, squirting ink and pumping jets of water into the females’ body (Davis, 2012). Females, on the other hand, were worn out by the physical restrain on them that caused reduced oxygen reaching her gills and also the lack of circulation of oxygenated blood around her body.

The reduction in physical performance post-copulation (also called “energetic costs”) could have several implications for some factors such as predator avoidance, foraging ability, and even mating behavior. (Franklin et al., 2012)

Given that these squids have lifespans of only about a year, there is thus a need to look into and account for these “energetic costs” from mating and the effects on physical performances of these squids after mating.