What do a seahorse father and a human mother have in common? Pregnancy.
But the similarities go further than simply carrying a baby, say scientists.
"Surprisingly, seahorse dads do a lot of the same things human mums do," said Camilla Whittington, co-author of a new study, in a press release.
Although seahorse dads carry their young for just 24 days and human gestation lasts nine months, what happens during pregnancy in both animals is remarkably similar, according to a study published Tuesday in the journal Molecular Biology and Evolution.
The brood pouch of a male seahorse is much more than a hangout for developing embryos. The pouch also nourishes and protects the growing swimmers, she explains.
"Seahorse babies get a lot of nutrients via the egg yolk provided by their mothers, but the pouch of the fathers has also evolved to meet the complex challenges of providing additional nutrients and immunological protection, and ensuring gas exchange and waste removal,” said Dr. Whittington.
Those additional nutrients include energy-rich lipids and calcium to support the growth of tiny seahorse bones. The researchers think the embryos absorb these nutrients when they are secreted into the brood pouch.
The similarities between seahorse and human pregnancy don't stop there.
By examining samples taken from seahorse brood pouches, the researchers determined that the some of the seahorses' genes are remarkably similar to that of diverse live-bearing mammals, reptiles, and fish, suggesting that there is a "common toolkit of genes regulating pregnancy in divergent evolutionary lineages."
“Regardless of your species, pregnancy presents a number of complex challenges, like ensuring you can provide oxygen and nutrients to your embryos,” said Whittington. “We have evolved independently to meet these challenges, but our research suggests that even distantly related animals use similar genes to manage pregnancy and produce healthy offspring.”
Seahorses are part of the only known family of animals, Syngnathidae, in which males take care of pregnancy.