Tuesday, February 24, 2009

"No good fish goes anywhere without a porpoise"...

... But I bet Lewis Carroll didn't have these zany creatures in mind when he said this. This month, we have not one but two freaky new fish facts.

Up first is the recently discovered four-eyed spookfish. Despite the name and its appearance, this fish only really has two eyes, but each one has two parts (an upwards-looking one and a downwards-facing one). It uses a lens to focus light (from the sun) coming in from the 'top eyes' and a mirror to focus light (from bioluminescence of other sea creatures) coming to the 'bottom eyes'. This means it can focus images from above and below simultaneously!

Up next are the wacky Tapetail/Whalefish/Bignose fishes. The shallow-water tapetail has a long streamery tail. The deep-water whalefish has no scales but huge jaws. And the Bignose, which also lives in the deep sea, unsurprisingly has a large 'nose' and immobile jaws. They couldn't possibly be related, right?

Wrong! New mtDNA analyses have shown that these are in fact different stages in the life cycle of the same fish family (Cetomimidae). After museum specimens of the fish were reexamined, the researchers have also found intermediate forms of each stage, showing that a tapetail larva grows into a whalefish female or a bignose male.

“This is an incredibly significant and exciting finding,” says Dr. David Johnson, an author on the paper. “For decades scientists have wondered why all tapetails were sexually immature, all bignose fishes were males and all whalefishes were females and had no known larval stages. The answer to part of that question was right under our noses all along—the specimens of tapetails and bignose fishes that were used to describe their original families included transitional forms—we just needed to study them more carefully.”

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