Expectant fathers

Sea Horses are unique creatures. They are fish but with their upright posture, bony outer shell (no scales) and curled tail, they are oddities - even in the wondrous world of underwater fauna.

But there is something else that makes the pretty little marine being even more unusual: Apart from their cousins, the pipefish, they are the only animal species in which the budding father is the one to get pregnant.

Rather than the male planting its sperm inside the mother, the females deposit their eggs in a pouch on their mate's body. And there they stay until the baby sea horses are born.

Underwater sci-fi?

It might sound a bit brave new world, but it turns out that these pregnancies are much closer to those of mammals like us humans than previously thought. A new study, published in the current issue of the journal #link:http://mbe.oxfordjournals.org/content/early/2015/09/01/molbev.msv177.abstract:Molecular Biology and Evolution# has taken a closer look at what goes on in the brooding pouch of big-belly seahorses (Hippocampus abdominalis).

It was already known that they secrete lipids and nutrients like calcium to feed the growing embryos, but the researchers looked at how expectant fathers' gene activity changes during the different stages of their offspring's development.

What they discovered was that key gene transcripts of reproductive functions in sea horses had the same origin as those in pregnant reptiles, live-bearing fish and even mammals. The researchers suspect that, despite our differences, we all use a "common toolkit of genes" to make sure our pregnancies go smoothly.