If you've wondered why seahorses look the way they do -- with an upright posture they share with humans but few other animals -- wonder no longer.
Researchers in Australia say it all happened 20 to 25 million years ago, when habitat lush with sea grass beds developed in waters between Australia and Indonesia -- habitat perfect for vertical fishes to grasp with curling tails.
Dr. Peter Teske, a postdoctoral fellow at the Macquarie University Molecular Ecology Lab in Sydney, told Discovery News that going upright would have been ideal for a weak-swimming animal living in this new environment. It also would have help seahorses camouflage themselves from predators -- and from potential prey.
He and co-author Luciano Beheregaray were able to pinpoint the timing by building a family tree for members of the Hippocampus genus (true seahorses) and the related genus Idiotropiscis, which includes the southern little pipehorse that is very similar in appearance.
They published their findings in the journal Royal Society Biology Letters.
The two lines diverged about 20 to 25 million years ago, the researchers concluded, isolating ancestral seahorses in a shallow, warm seas and a grassy sea bed -- new habitat to which they adapted well.
As you can tell from a visit to The Secret Lives of Seahorses, these fishes still prefer sheltered habitats like sea grass beds, mangroves and coral reefs.
Jennifer Viegas, who wrote the Discovery News article, includes some of her favorite seahorse photos in her "Born Animal" blog, as well as a piano solo called Seahorse by composer/pianist Margie Adam.