Chaunax, variously known as coffinfishes, gapers, or frogmouths, is a genus of marine ray-finned fishes. It is one of two genera belonging to the familyChaunacidae, the sea toads. They are found in tropical and subtropical oceans around the world, typically in deep water.
Chaunax sea toads have a rotund, slightly laterally flattened body which tapers to a small rounded caudal fin. The head is large and globelike with a large oblique mouth and eyes set high on the head. The eyes are covered in transparent skin, resembling a window. The teeth in the mouth are vertical, small, thin, and sharp. There is a single visible dorsal spine, the illicium, which is relatively short, sits in an oval-shaped depression on the snout, and is tipped with a tuft of filaments, the esca, or lure. The two other dorsal spines are embedded in the skin. The dorsal fin is located on the rear of the body and is supported by 10 or 12 soft rays, while the anal fin contains 6 or 7 soft rays. The loose, flabby skin has a dense covering of very small denticles. The lateral line is open and runs from the caudal peduncle to the head, with obvious canals connecting to branches under the eye, on the chin, and along the lower flanks. The main part of the lateral line on the upper body contains between 29 and 42 pores, with between 11 and 13 pores on the head.[13] These are mostly rather small species, with the largest being C. picus, with a maximum published total length of 40 cm (16 in), while the smallest is C. breviradius, which has a maximum published standard length of 11 cm (4.3 in).[7]
Distribution and habitat
Chaunax anglerfishes are found in all three oceans of the world. They are benthic fishes, found at depths between 90 and 2,000 m (300 and 6,560 ft).[14]
Biology
Chaunax coffinfishes are only distantly related to the frogfishes of the family Antennariidae but have a similar lifestyle as ambush predators, luring prey to within striking distance of their large mouth with the illicium and esca, and using their pectoral and pelvic fins to walk along the bottom.[15] At least one species, C. endeavouri, has been observed inflating its gill chambers by holding onto water. The retained water can inflate their gill chambers so that their bodies become as much as 30% larger, and this water can be retained for lengths of time from 26 seconds up to 4 minutes. These deep-water ambush predators rely on prey coming close enough to strike, which can be infrequent, so the ability to hold water in the gills for longer may be an adaptation to preserve energy while breathing, as well as possibly being a defence against predators. However, the fishes cannot keep the water within the gill chambers if bitten by a predator.[16]
^Ho, H.-C. and W.-C. Ma (2022). "Four new species of the frogmouth genus Chaunax (Lophiiformes: Chaunacidae) from Taiwan and the Philippines". Zootaxa. 5189 (1): 146–179. doi:10.11646/zootaxa.5189.1.17.
^Ho, Hsuan-Ching; Meleppura, Rajeesh Kumar; Bineesh, K. K. (2016). "Chaunax multilepis sp. nov., a new species of Chaunax (Lophiiformes: Chaunacidae) from the northern Indian Ocean". Zootaxa. 4103 (2): 130–136. doi:10.11646/zootaxa.4103.2.3. PMID27394623.
^John H. Caruso (1989). "Systematics and Distribution of the Atlantic Chaunacid Anglerfishes (Pisces: Lophiiformes)". Copeia. 1989 (1): 153–165. doi:10.2307/1445616.
