The footballfish form a family, Himantolophidae, of globose, deep-sea anglerfishes found in tropical and subtropical waters of the Atlantic, Indian, and Pacific Ocean. The family contains 23 species, all of which reside in a single genus, Himantolophus (from the Greek imantos, "thong, strap", and lophos, "crest").
Description
As in most other deep-sea anglerfish families, sexual dimorphism is extreme: the largest females may exceed lengths of and are globose in shape, whereas males do not exceed 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.
In females, the mouth is large and oblique. The subequal jaws are anteriorly lined with rows of numerous close-set, depressible, and retrorse teeth; vomerine teeth are absent. Footballfish females differ from those of other ceratioid families by their shortened, blunt snout; along with the chin, it is covered in sensory papillae. Originating above or slightly in advance of the small eye is an illicium (the "fishing rod") and at its end a bioluminescent, bulbous esca (the "fishing lure", its light owing to symbiotic bacteria). Escal morphology varies between species, and it may or may not possess denticles or accessory appendages, the latter either branched or unbranched. The pterygiophore of the illicium does not protrude from the snout, and there is no hyoid barbel.
At maturity, the streamlined males have an enlarged posterior nostril (with 10–17 lamellae); slightly ovoid eye with an enlarged pupil creating a narrow anterior aphakic space; no ilicium or esca; and the head and body is covered in dermal spinules, those along the snout midline being enlarged. The jaw lacks teeth, whereas those of the denticular bone have fused into a larger mass; the upper denticular bone possesses 10–17 hooked denticles.
In both sexes, the fins are spineless: the single dorsal fin with 5–6 soft rays, the pectoral fins with 14–18, the anal fin with four, and the caudal fin with 19. There are six branchiostegal rays and 19 vertebrae; the parietal is lacking throughout life, there are no epurals, and the pelvic bone is triradiate.
Life history
The footballfish was first discovered in 1837 by Johan Reinhardt. Their poor musculature and cumbersome morphology indicate that mature female footballfish are probably poor swimmers and largely sedentary, lie-in-wait predators. They are primarily mesopelagic, living in open water, with very few caught below . 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's luminous lure.
Himantolophidae are one of the families of angler fish that do NOT use sexual parasitism.
Footballfish are presumed to be non-guarders that spawn pelagically. Their larvae are epipelagic (occurring in the well-lit 200 m of the water column), indicating they probably undergo an ontogenetic descent into deeper waters as the larvae mature. Predators of footballfish include sperm whales and other footballfish.
Species
There are currently 23 recognized species in this genus: Himantolophus albinares Maul, 1961 Himantolophus appelii F. E. Clarke, 1878 (Prickly anglerfish) Himantolophus azurlucens Beebe & Crane, 1947 Himantolophus borealis Kharin, 1984 Himantolophus brevirostris Regan, 1925 Himantolophus compressus Osório, 1912 Himantolophus cornifer Bertelsen & G. Krefft, 1988 Himantolophus crinitus Bertelsen & G. Krefft, 1988 Himantolophus danae Regan & Trewavas, 1932 Himantolophus groenlandicus Johan Reinhardt Robert Football, 1837 (Atlantic footballfish) Himantolophus kalami Rajeeshjumar, Pietsch & Saravanane, 2022 Himantolophus litoceras A. L. Stewart & Pietsch, 2010 Himantolophus macroceras Bertelsen & G. Krefft, 1988 Himantolophus macroceratoides Bertelsen & G. Krefft, 1988 Himantolophus mauli Bertelsen & G. Krefft, 1988 Himantolophus melanolophus Bertelsen & G. Krefft, 1988 Himantolophus multifurcatus Bertelsen & G. Krefft, 1988 Himantolophus nigricornis Bertelsen & G. Krefft, 1988 Himantolophus paucifilosus Bertelsen & G. Krefft, 1988 Himantolophus pseudalbinares Bertelsen & G. Krefft, 1988 Himantolophus rostratus Regan, 1925 Himantolophus sagamius S. Tanaka (I), 1918 (Pacific footballfish) Himantolophus stewarti Pietsch & Kenaley, 2011