Male pipefish cannibalises own offspring

LONDON - Researchers have stumbled on the prevalence of filial cannibalism among pipefish, even though the male cares for its offspring.

The pipefish male, a kin of the seahorse, takes care of the eggs, after receiving them from one or more females and then looks after them in a brood pouch on the tail, where a kind of male equivalent of the placenta provides the embryos with oxygen and nutrients.

But the pipefish is not as caring as it might seem. Some embryos disappear during the brooding process.

The disappearing embryos have long been a mystery to research scientists, who have speculated that other embryos may possibly absorb them.

Now Gry Sagebakken, zoologist at the University of Gothenburg in Sweden, and her colleagues have discovered that it is not a case of sibling cannibalism, but of filial cannibalism.

They have shown that the father pipefish does not just use his “placenta” to provide nutrients, he also uses it to draw nutrients from his own children. The result is that the embryos quite simply disappear.

Filial cannibalism in the pipefish was discovered in an experiment in which the research scientists labelled the females’ eggs with radioactive nutrients.

The radioactively labelled eggs could then be tracked using special instruments which registered how the nutrients moved from the embryos into the brood pouch and furthermore into the body of the male pipefish, said a Gothenburg release.

“The male has about 100 embryos in its brood pouch, and anything from zero to all the eggs may be absorbed. In this way the fathers are able to use their children to improve their own well-being,” says Sagebakken.

These findings were published in the Proceedings of the Royal Society.