The parasitic males use their enlarged olfactory bulbs (as indicated by their enlarged nostrils) and sensitive eyes to home in on the pheromones and possibly the species-specific lures of females. ![]() Upon maturity, the tiny males of most species metamorphose into a parasitic form, which lacks both a lure and true teeth and is presumed not to feed. 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. They are primarily mesopelagic, living in open water, with very few caught below 1,000 metres (3,300 feet 550 fathoms). Their poor musculature and cumbersome morphology indicate that mature female footballfish are probably poor swimmers and largely sedentary, lie-in-wait predators. The footballfish was first discovered in 1837 by Johan Reinhardt. There are six branchiostegal rays and 19 vertebrae the parietal is lacking throughout life, there are no epurals, and the pelvic bone is triradiate. 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. ![]() 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. The pterygiophore of the illicium does not protrude from the snout, and there is no hyoid barbel.Īt 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. Escal morphology varies between species, and it may or may not possess denticles or accessory appendages, the latter either branched or unbranched. 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). Footballfish females differ from those of other ceratioid families by their shortened, blunt snout along with the chin, it is covered in sensory papillae. The subequal jaws are anteriorly lined with rows of numerous close-set, depressible, and retrorse teeth vomerine teeth are absent. ![]() In females, the mouth is large and oblique.
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