Seahorses are Nature’s only example of male surrogate mothers

This edited article about the sea-horse originally appeared in Look and Learn issue number 710 published on 23 August 1975.

Seahorses

The strange little creature looked more like a chess knight than a fish as it swam in the warm shallow waters near the coast of Portugal.

It was a male, about 7 in. (17.5 cm.) long, and it moved forward in an upright position, propelling itself by means of a rapidly-oscillating fin on its back.

Besides the horse-like head which gave it its name it had a flexible, prehensile tail which it could wrap around seaweed stems for support in the way that some monkeys use tree branches. In addition, it had a pouch in its abdomen like a kangaroo.

The sea-horse fed as it swam, sucking into its mouth tiny fish and small crustacea from a distance of up to 1 and a half inches (4 cm.).

Presently it encountered another sea-horse, a female, and a fantastic courtship dance began which lasted 24 hours. The two fish bobbed up and down and swam in small circles around each other until, eventually, the dance ended when the male appeared to bow several times to his partner (in reality he was pumping out the water from his pouch).

The female then approached and inserted her long egg-laying tube (ovipositor) into the pouch and laid nearly 200 eggs. When this operation was completed the pouch closed and the female swam off, abandoning all further responsibility for the welfare of her future family.

About a month later the eggs hatched and the young sea-horses were shot out of the pouch one by one by a series of muscular convulsions on the part of the father. When the last baby had been born the adult sea-horse was completely exhausted.

No one knows why the roles of the parents should be reversed in this remarkable way.

Sea-horses are fish which normally live in the warmer seas of the world but they sometimes come as far north as the south-west coast of Britain, so look out for them if ever you are on holiday in Cornwall.