Chaunax Explained

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 family Chaunacidae, the sea toads. They are found in tropical and subtropical oceans around the world typically in deep water.

Taxonomy

Chaunax was first proposed as a monospecific genus in 1846 by the English naturalist Richard Thomas Lowe when he described Chaunax pictus as a new species from Madeira. There are three species groups within the genus; C. pictus, containing 3 species, C. abei containing 17 species and C. fimbriatus containing 9 species.[1] [2] This genus is classified within the family Chaunacidae, the sea toads, one of two genera in that family, the sea toads are placed within the monotypic suborder Chaunacoidei within the anglerfish order Lophiiformes.[3]

Etymology

Chaunax means "one who gapes", from chanos meaning "to gape", an allusion to the large, wide mouths of these fishes.[4]

Species

There are currently 29 recognized species in this genus:

Characteristics

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.[10] These are mostly rather small species with the largest being C. picus, with a maximum published total length of, while the smallest is C. breviradius, which has a maximum published standard length of .

Distribution and habitat

Chaunax anglerfishes are found in all three oceans of the world, they are benthic fishes which are found at depths between .[11]

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 useing their pectoral and pelvic fins to walk along the bottom.[12] 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 and this 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.[13]

Notes and References

  1. Book: Theodore W Pietsch . Theodore Wells Pietsch III . Order Lophiiformes . 281–307 . Coastal Fishes of the Western Indian Ocean . 2 . . Elaine Heemstra . David A Ebert . Wouter Holleman . . 2022 . 978-1-990951-29-9 . South African Institute for Aquatic Biodiversity .
  2. 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 . 10.11646/zootaxa.5189.1.17.
  3. Book: Nelson, J.S. . Joseph S. Nelson . Grande, T.C. . Wilson, M.V.H. . 2016 . Fishes of the World . 5th . . Hoboken, NJ . 508–518 . 978-1-118-34233-6 . 2015037522 . 951899884 . 25909650M . 10.1002/9781119174844.
  4. Web site: Order LOPHIIFORMES (part 1): Families LOPHIIDAE, ANTENNARIIDAE, TETRABRACHIIDAE, LOPHICHTHYIDAE, BRACHIONICHTHYIDAE, CHAUNACIDAE and OGCOCEPHALIDAE . Christopher Scharpf . 14 November 2022 . 26 April 2024 . The ETYFish Project Fish Name Etymology Database . Christopher Scharpf.
  5. Ho . Hsuan-Ching . Last . Peter R. . Two new species of the coffinfish genus Chaunax (Lophiiformes: Chaunacidae) from the Indian Ocean . Zootaxa . 2013 . 3710 . 5 . 436–448 . 10.11646/zootaxa.3710.5.3. free .
  6. Ho . Hsuan-Ching . Ma . Wen-Chun . Revision of southern African species of the anglerfish genus Chaunax (Lophiiformes: Chaunacidae), with descriptions of three new species . Zootaxa . 2016 . 4144 . 2 . 175–194 . 10.11646/zootaxa.4144.2.2. free .
  7. Ho . Hsuan-Ching . Kawai, T. . Satria, F. . 2015 . Species of the anglerfish genus Chaunax from Indonesia, with descriptions of two new species (Lophiiformes: Chaunacidae) . Raffles Bulletin of Zoology . 63 . 301–308 . 2022-11-09 . 2015-09-27 . https://web.archive.org/web/20150927164618/http://lkcnhm.nus.edu.sg/nus/images/data/raffles_bulletin_of_zoology/vol63/63rbz301-308.pdf . dead .
  8. Ho . Hsuan-Ching . Roberts . Clive D. . Stewart . Andrew L. . A review of the anglerfish genus Chaunax (Lophiiformes: Chaunacidae) from New Zealand and adjacent waters, with descriptions of four new species . Zootaxa . 2013 . 3620 . 1 . 89–111 . 10.11646/zootaxa.3620.1.4. free .
  9. Ho . Hsuan-Ching . Meleppura . Rajeesh Kumar . Bineesh . K. K. . Chaunax multilepis sp. nov., a new species of Chaunax (Lophiiformes: Chaunacidae) from the northern Indian Ocean . Zootaxa . 2016 . 4103 . 2 . 130–136 . 10.11646/zootaxa.4103.2.3 . 27394623.
  10. Web site: Genus: Chaunax, Frogmouths, Gaper, Gapers . 5 May 2024 . Shorefishes of the Greater Caribbean online information system . Smithsonian Tropical Research Institute.
  11. John H. Caruso . 1989 . Systematics and Distribution of the Atlantic Chaunacid Anglerfishes (Pisces: Lophiiformes) . Copeia . 1989 . 1 . 153–165 . 10.2307/1445616.
  12. Web site: Bray, D.J. . 2022 . Coffinfishes, CHAUNACIDAE . Fishes of Australia . 5 May 2024 . Museums Victoria.
  13. Web site: Coffinfish Can Hold Their Breath for Up to Four Minutes on the Ocean Floor . Meilan Solly . 1 July 2019 . 5 May 2024 . Smithsonian Magazine.

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