Female southern bottletail squid consume ejaculates of their mates and use the nutrients to help in the growth of their unfertilised eggs, according to a new study.

This is the first time that researchers have noticed such a trait in any species of cephalopod - a group including squid, octopus, cuttlefish and nautilus. The research team led by PhD student Benjamin Wegener and Dr Bob Wong from Monash University's School of Biological Sciences, Australia, found that male squid place sperm packages into an external pouch below the mouth of the female.

The sperm packages are deposited into the pouch for egg fertilization. Theoritically, when a sperm package is placed inside the pouch it turns inside out and releases the sperm. The female squid then places an unfertilized egg on the sperm, reported LiveScience.

But, most of the time, the female squid eats the sperms as snack, which in turn provides nutrition to the females as well as the unfertilized eggs.  

Researchers also found that the smaller females ingested more of the male's ejaculate than larger females. This could explain as to why male squid prefer to mate with larger females. They do so to minimise ejaculate consumption and increase egg fertilization.

"A male's sperm packages, called spermatophores, take time to produce and he must pass several to the female if he hopes to fertilise her eggs. If she is using the nutrients received from ejaculate consumption to develop her unfertilised eggs, he may even be helping the next male that mates with her," Wegener said in a statement.

"By targeting those larger females less likely to consume their spermatophores, male southern bottletail squid attempt to maximise their chances for successful egg fertilization," he said.

The findings of the study are published in the journals Biology Letters and Behavioral Ecology.

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