Showing posts with label
Why Are Anglerfish So Freaky?.
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Showing posts with label
Why Are Anglerfish So Freaky?.
Show all posts
Longhead Dreamer Anglerfish
Looking like a creature from the Alien movies, this nightmarish "longhead dreamer" anglerfish (Chaenophryne longiceps) was until recently an alien species to Greenland waters.
The dreamer, which grows to a not-so-monstrous 6.7 inches (17 centimeters) in length, is 1 of 38 fish species found around the Arctic island for the first time, according to a recent study led by biologist Peter Møller of the Natural History Museum of Denmark in Copenhagen.
Ten of the species new to Greenland are new to science too. All 38 were discovered since the last such survey in 1992.
Rising ocean temperatures due to global warming—which could be drawing unfamiliar fishes to the region—and increased deep-sea fishing may be responsible for the spike in fresh fish faces seen off Greenland, according to the study, published in February in the journal Zootaxa. (Learn about global warming.)
Football Fish
The footballfish are a family, Himantolophidae, of globose, deep-sea anglerfishes found in tropical and subtropical waters of the Atlantic, Indian, and Pacific Ocean. The family contains c. 19 species all in a single genus, Himantolophus (from the Greek imantos, "thong, strap", and lophos, "crest").
As in other deep-sea anglerfish families, sexual dimorphism is extreme: the largest females may exceed lengths of 60 cm (two feet) and are globose in shape, whereas males do not exceed 4 cm (1.5 inches) as adults and are comparatively fusiform. Their flesh is gelatinous, but thickens in the larger females, which also possess a covering of "bucklers" — round, bony plates each with a median spine — that are absent in males. Both are a reddish brown to black in life.
The football fish was first discovered in the early 1900s by deep sea fisherman in search of flounder.Their poor musculature and cumbersome morphology indicate that female footballfish at least are probably poor swimmers and largely sedentary, lie-in-wait predators. They are primarily mesopelagic, living in open water, with very few caught below 1,000 m (3,280 ft). Females are carnivorous and feed upon other pelagic fish (such as lanternfishes and ridgeheads) and cephalopods, as well as shrimp and euphausiids that are presumably attracted to within striking distance by the footballfish' luminous lure.
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.
Wolf-Trap Anglerfish (Lasiognathus)
Lasiognathus is a genus of deep-sea anglerfish in the family Thaumatichthyidae, with five species known from the Atlantic and Pacific Oceans. It has been called a "compleat angler", in that its lure apparatus consists of a fishing rod (the projecting basal bone or pteropterygium), a fishing line (the illicium, a modified dorsal fin ray), bait (the bioluminescent esca), and hooks (large dermal denticles). It is also distinctive for an enormous upper jaw with premaxillaries that can be folded down to enclose the much shorter lower jaw.
The closest relative of Lasiognathus is Thaumatichthys, which also has enlarged and hinged premaxillaries, escal denticles, and a branched upper operculum. However, there are significant differences between those two taxa as well, which includes characters that Lasiognathus shares with the oneirodids not found in Thaumatichthys. Bertelsen and Struhsaker (1977) noted that, given the undefined cladistics of the Oneirodidae, it was somewhat subjective whether Lasiognathus and Thaumatichthys were placed in their own family, in separate families, or in the Oneirodidae. Lasiognathus comes from the Ancient Greek lasios, meaning "hairy", and gnathos, meaning "jaw".
