May 6, 2009 -- Seahorses first stood up sometime after 25 to 20 million years ago, when bodies of open water between Australia and Indonesia changed, leaving these horse-resembling bony fishes with shallow sea grass habitat, according to a new study. The study, published in the latest Royal Society Biology Letters, explains that an upright stature, shared by humans but which is extremely rare throughout the entire animal kingdom, allowed seahorses to reside in what was essentially a lawn under water. To this day, seahorses prefer to live in sheltered areas, such as sea grass beds, coral reefs and mangroves. "Not only can an upright fish maneuver much better in such an environment than a horizontally-swimming one, but the upright sea grass blades would have improved their camouflage," explained Peter Teske, who co-authored the paper with Luciano Beheregaray. "Camouflage is of great importance to seahorses, which are poor swimmers," added Teske, a postdoctoral researcher in Macquarie University's Molecular Ecology Lab. "It affords them both protection from predators and allows them to sneak up on their prey -- including small crustaceans and tiny fish -- without being noticed." Related Content:
Teske and Beheregaray first took note of pygmy pipehorses, which look like "non-upright proto-seahorses." They wondered when these two bony fishes diverged, and how this fit into the bigger picture for the Syngnathidae, a family of fish that includes seahorses, pipefishes and both weedy and leafy sea dragons. To answer these questions, they constructed a family tree using genetic information gathered from the genus Hippocampus, which includes all seahorses, and the genus Idiotropiscis, which contains the very seahorse-resembling southern little pipehorse. Molecular dating indicates seahorses split from their pygmy pipehorse sister taxon during the Late Oligocene, right when tectonic events in the Indo-West Pacific resulted in the formation of new shallow water sea grass habitats. It appears that seahorses remained mostly isolated in these new regions, allowing them to evolve a number of distinctive features. "Seahorses are often considered to be highly unusual bony fishes because of their upright posture, their hard exoskeleton, their long suction-snout, their prehensile tail and the fact that it's the males that give birth," Teske explained. Virtually all male bony fishes are dutiful dads, but none compares to this fish super father. "The most advanced form of male parental care is found in the seahorses, where a brood pouch has evolved that resembles a placenta, and male seahorses even go into labor!" he marveled. Get More NewsSpiders, Scorpions Among World's Oldest CreaturesMany creepy crawlies have been on Earth much longer than previously believed.Blood-Sucking Vampire Bats Sing DuetsWhite-winged vampire bats "harmonize" with separated roost mates.Oldest Hebrew Writing Possibly FoundAncient inscriptions on a 3,000-year-old pottery shard could make history.Rare, Prehistoric-Age Reptile Found in N.Z.A tuatara has been spotted on the New Zealand mainland for the first time in 200 years.Iceman Has No Living RelativesOetzi, the 5,300 year-old frozen mummy, left no living genetic legacy.SLIDE SHOW: Landscapes of TerrorWhat makes a place feel scary? There are scientific explanations.It's Official: People Are Warming the PolesHumans are conclusively to blame for polar warming, say scientists.Eight-Armed Animal Preceded DinosaursWhat may be one of Earth's first animals was no bigger than a coaster and had eight arms.Phoenicians Live on in People's GenesOne in 17 Mediterranean men may be descended from ancient Phoenicians.Pesticides, Fertilizers Linked to Frog DeclineA pesticide is found to promote parasites among amphibians.Hubble Telescope Taking Photos AgainThe Hubble Space Telescope is once again snapping stunning photos of the universe.Andean Mummy Hairs Show Hallucinogen UseScientists find direct evidence of hallucinogenic drug use among ancient Andeans.Opals on Mars Reveal Planet's Long Wet PastOpals found on Mars suggest the planet has been wet for much longer. |
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