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Fishes with hands

The previously known spotted handfish, seen above in a file photo, is found on sandy sediments at the bottom of Tasmania's Derwent Estuary and adjoining bays. The fish use their fins to walk along the seabed, where they eat small invertebrates such as worms and crustaceans.

Perhaps the best studied species of the handfish family, the spotted handfish is listed as critically endangered by the International Union for Conservation of Nature—meaning it's "facing an extremely high risk of extinction in the wild in the immediate future."

Handfish's slow movements and tendencies to stay within tightly confined habitats would seem to make the fish easy targets for predators. But researchers think handfish have a secret weapon: a toxic skin that kills most attackers. (Related: "Venomous Fish Far Outnumber Snakes, Other Vertebrates, Study Says.")
Anecdotal stories suggest predators may die within an hour of eating a handfish, said CSIRO fish taxonomist Gledhill.

The red handfish, a previously known species, is listed as vulnerable in Australia, where it's found only around the southern island state of Tasmania.

Not much is known about handfish, because their populations are low and they are not often seen in the wild. But researchers suggest handfish lay fewer eggs than most other fish species, which means their long-term survival is a concern.

Handfish also tend to stay very close to home, so they don't adapt well to new places, said fish taxonomist Gledhill.


Newly described as its own species, the Ziebell's handfish typically has yellow fins, as seen above in a file photo, but the species can also appear with a mottled purplish coloration. Ziebell's handfish is found only in small, isolated populations off Tasmania and is listed as vulnerable in Australia.

Today all handfish are found only around southeastern Australia. But about 50 million years ago the animals likely inhabited regions around the world, the CSIRO scientists note. Fossils of the curious creatures have been discovered in the Mediterranean, for example.


Using its fins to walk, rather than swim, along the ocean floor in an undated picture, the pink handfish is one of nine newly named species described in a recent scientific review of the handfish family. 

Only four specimens of the elusive four-inch (ten-centimeter) pink handfish have ever been found, and all of those were collected from areas around the city of Hobart (map), on the Australian island of Tasmania.
Though no one has spotted a living pink handfish since 1999, it's taken till now for scientists to formally identify it as a unique species.

The new-species determinations were made based on a number of factors, including number of vertebrae and fin rays, coloration, the presence of scales and spines, and proportional body measurements, according to review author Daniel Gledhill of Australia's Commonwealth Scientific and Industrial Research Organisation, or CSIRO.

All of the world's 14 known species of handfish are found only in shallow, coastal waters off southeastern Australia, the review notes.

Even among the previously known species, the fish are poorly studied, the review authors add, and little is known about their biology or behavior.

Reference:
NGO

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