Thursday, July 8, 2010

July 8, 2010 : Wonder-fish

Wonder-fish (Thaumatichthys)

Thaumatichthys is a genus of deep-sea anglerfish in the family Thaumatichthyidae, with three known species. Its scientific name means "wonder-fish" in Greek; oceanographer Anton Bruun described these fishes as "altogether one of the oddest creatures in the teeming variety of the fish world." In contrast to other anglerfishes, the bioluminescent lure (called the "esca") of Thaumatichthys is located inside its cavernous mouth. They are worldwide in distribution and are ambush predators living near the ocean floor.

The first specimen of Thaumatichthys was collected by an American expedition in Indonesia in 1908 and given the species name pagidostomus ("trap-mouthed"). A subsequent specimen from the north Atlantic was placed by Regan and Trewavas (1932) into a new genus, Amacrodon, based on differences in dentition. Bruun assigned a specimen collected by the Galathea Expedition of 1950–52 to a third genus, Galatheathauma ("Galathea's wonder"), as it was much larger than the previous specimens. However, a later examination of the then-32 known specimens showed that these differences were attributable to age, and thus there was only one valid genus, Thaumatichthys, with three species.
The closest relative of Thaumatichthys is Lasiognathus, which also possesses enlarged, hinged premaxillaries, denticles on the esca, and a branched upper operculum. There are also significant differences between the two genera though, and Lasiognathus shares many more traits with the Oneirodidae (in which it was formerly placed) than does Thaumatichthys.

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