| Double angler | |
|---|---|
 | |
| Diceratias bispinosus | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Lophiiformes |
| Suborder: | Ceratioidei |
| Family: | Diceratiidae Regan &Trewavas, 1932 |
| Genera | |
See text | |
| Synonyms | |
| |
Double anglers ordoublespine seadevils comprise thefamilyDiceratiidae,[1] being a small and little knownfamily of rarely encountered marineray-finned fishes belonging to theorderLophiiformes, the anglerfishes. The two genera and seven species of this family are found in the deeper waters of the tropical and subtropical Atlantic, Indian and Pacific Oceans. They are distinguished from other deep sea anglerfishes by the possession of a second bioluminescent cephalic spine. The fishes in this family were known only frommetamorphosed females and the males were not described until 1983.
The double angler family, Diceratiidae, was first proposed as a family in 1932 by the BritishichthyologistsCharles Tate Regan andEthelwynn Trewavas.[2] Thetype genus of the family,Diceratias, had been proposed as a subgenus ofCeratias in 1887 by the German-born British ichthyologistAlbert Günther with itstype species beingCaratias bispinosus which Günther haddescribed from aholotype collected from offBanda Island at a depth of 360 fathoms (2,160 ft; 660 m) on theChallenger expedition of 1872-1876.[3] The 5th edition ofFishes of the World classifies this family in thesuborderCeratioidei of theanglerfishorderLophiiformes.[4]
The double angler family name is derived from the genus nameDiceratias which prefixesdi, meaning "two" onto the genus nameCeratias. This genus was thought to be asubgenus ofCeratias with two cephalic spines instead of one.[5]
The double angler family, Diceratiidae, is made up of two genera with seven recognised valid species:
Doubleanglers aresexually dimorphic. The metamorphosed females can be separated from other females in the suborder Ceratioidei by the possession of a second, club-like exposed cephalic spine bearing abioluminescent organ at its tip. They also have a large mouth which reaches back beyond the eye, a well developed spine on thesymphysis of themandible which reaches just past themaxilla, the presence ofvomerine teeth,[6] there are spines in the skin, thedorsal fin has between five and seven rays while theanal fin has four rays and they have a small pelvic bone which is joined to thecleithrum. The second cephalic spine is positioned directly behind the base of the first cephalic spine, orillicium[4] and can be pulled down beneath the skin in individuals with a total length greater than 1.3 cm (0.51 in) leaving a small pore to show its location.[7] These anglerfishes vary in length from a maximum publishedstandard length of 10.1 cm (4.0 in) forBufoceratias shaoi to a maximum publishedtotal length of 25 cm (9.8 in) forB. wedli.[8] The males have spinules in the skin, they have two teeth on the snout and two transverse rows of 4 or 5 teeth on the lower jaw, all separate from each other. The eyes and nostrils of the males are directed laterally.[9][1]
Doube anglers are found in the Atlantic, Pacific and Indian oceans in tropical and subtropical waters over thecontinental shelf andcontinental margin,[4] at depths between 0 and 2,306 m (0 and 7,566 ft).[10][11]
Double anglers are rare fishes and only the metamorphosed females have been described, the males are thought to be free-living and not to besexual parasites of the females.[12]