March 3, 2009
Courtesy University of Washington
and World Science staff
Psychedelica seems the perfect name for a fish that is a wild swirl of tan and peach zebra stripes and acts in ways contrary to its brethren. So says the University of Washington’s Ted Pietsch, who is the first to describe the new species in the scientific literature and thus the one to pick the name. With its flattened face, scientists say the fish's eyes appear to be directed forward. These may provide it with binocular vision, a special attribute well developed in humans that provides the ability to accurately judge distance. Only very few fishes have eyes whose field of vision overlaps in front, providing such vision. (©David Hall Psychedelica is perhaps even more apt given the cockamamie way the fish swim, some with so little apparent control they look drunk. Members of Histiophryne psychedelica don’t so much swim as hop. Each time they strike the seafloor they use their fins to push off and they expel water from tiny gill openings on their sides to jettison themselves forward. With tails curled tightly to one side – which limits their ability to steer – they look like inflated rubber balls bouncing hither and thither. The leg-like pectoral fins used for walking are commonly found in anglerfish which prefer crawling to swimming. More than a dozen individual fish have been seen in Ambon Harbor, Indonesia, since divers with Maluku Divers first spotted one of the fish in January 2008. The fish have been found in 15 to 25 feet of water near a commercial jetty in the busy harbor. (Credit: ©David Hall The species has a flattened face with eyes directed forward. It’s something Pietsch, with 40 years of experience studying and classifying fishes, has never seen before in frogfish. It causes him to speculate that the species may have binocular vision, that is, vision that overlaps in front, like it does in humans. Most fish, with eyes on either side of their head, don’t have this; they see different things with each eye.
While other frogfish and similar species are known to jettison themselves up off the bottom before they begin swimming, none have been seen hopping, according to Pietsch. It’s just one of the behaviors of H. psychedelica unseen in any other fish, added the researcher, lead author of a paper on the new species in Copeia, the journal of the American Society of Ichthyologists and Herpetologists.
It was little more than a year ago that the fish with rare, forward-facing eyes like humans and a secretive nature drew worldwide attention after having been observed in the busy harbor of Ambon Island, Indonesia. An adult fish was observed in January 2008 by Toby Fadirsyair, a guide, and Buck and Fitrie Randolph, co-owners of Maluku Divers, based in Ambon. They and other co-owners Andy and Kerry Shorten eventually found Pietsch to help them identify the fish. Since the first sighting divers have observed a number of adults and juveniles, now that they know what to look for.
Adults of H. psychedelica are fist-sized with gelatinous bodies covered with thick folds of skin that protect them from sharp-edged corals as they haunt tiny nooks and crannies of the harbor reef. Fins on either side of their bodies have, as with other frogfish, evolved to be leg-like, and members of H. psychedelica actually prefer crawling to swimming. (See a QuickTime video of the animal here.)
DNA work indicated H. psychedelica joins two other species in a genus called Histiophryne, though the other two look very drab in comparison. The genus is but one of about a dozen in the frogfish or Antennariidae family, according to Pietsch. The frogfish are, in turn, part of the larger order of Lophiiformes, or anglerfish.
Unlike other anglerfish, members of H. psychedelica have no lures growing out of their foreheads to attract prey. The other anglerfish sit out in the open on the seafloor or coral reefs, often adapting their coloring so their bodies are camouflaged, but the lures are meant to be noticed so the fish wave, wiggle and sometimes blink the lures on and off.
Instead of that showiness, members of H. psychedelica are shy and secretive, probably one reason they weren’t previously spotted, Pietsch said. When a member of H. psychedelica is uncovered by divers it usually seeks a new place to hide within 10 or 15 minutes.
And while other anglerfish change their coloring depending on the environment, the new species appears to maintain its wild striping no matter the surroundings.
The coloring led co-author David Hall, a wildlife photographer and owner of seaphotos.com, to speculate that the fish is mimicking corals. Indeed, Hall produced photos for the new scientific paper showing corals the animals may be mimicking.
The other co-author, Rachel Arnold, a master’s student at the uni-ver-sity, did the DNA work. Arnold, who dove in Ambon Harbor last year, said the striping of each fish is distinctive, “like a fingerprint of patterning on their body so from whatever angle you look, you can tell individuals apart.”
The scientists found, however, that the vivid colors faded in a matter of days once a specimen was preserved in ethanol. The flesh of the preserved specimen looks white, but with a microscope one can still see the striping, Pietsch discovered.
This got him thinking about two specimens sent to him in 1992 that he’d kept. The Dallas Aquarium had sent him two frogfish, found in a shipment of live fishes from Bali that they said had unusual pigment patterns. The staff had nicknamed them “paisley frogfish.” But the photograph Pietsch was sent was of poor quality and the preserved specimens Pietsch received were white, so he didn’t give them much thought.
Pietsch retrieved the old specimens from the collection, put them under a microscope and found the striping distinctive to H. psychedelica. He’d had two specimen of a new species of fish for 17 years, but didn’t know it.
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