Callorhinchus
Callorhinchus Temporal range:
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Callorhinchus milii
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Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Chondrichthyes |
Subclass: | Holocephali |
Order: | Chimaeriformes |
Family: | Callorhinchidae , 1901
Garman |
Genus: | Callorhinchus Lacépède, 1798 |
Species | |
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Callorhinchus, the plough-nosed chimaeras or elephantfish, are the only living
Morphology
Plough-nose chimaeras range from about 70 to 125 cm (2.30 to 4.10 ft) in total length.[3] Their usual color is black or brown, and, often a mixture between the two. While the club-like snout makes elephantfish easy to recognize, they have several other distinctive features. They possess large pectoral fins, believed to aid in moving swiftly through the water. They also have two dorsal fins spaced widely apart, which help identify the species in the open ocean.[4] In front of each pectoral fin is one single gill opening. Between the two dorsal fins is a spine, and the second dorsal fin is significantly smaller than the more anterior one. The caudal fin is divided into two lobes, the top one being larger.[5] The eyes, set high on the head, are often green in color.
The snout is used to probe the sea bottom in search of the invertebrates and small fishes on which it preys.[1] The remainder of the body is flat and compressed, often described as elongated. The mouth is just under this snout and the eyes are located high on top of the head. They have broad, flat teeth that have adapted for this eating habit, two pairs that reside in the upper jaw and one pair in the lower jaw. In addition to its use for feeding, the "trunks" of the Callorhinchus fish can sense movement and electric fields, allowing them to locate their prey.
Phylogeny
Distribution
Members of this genus are all found in subtropical and temperate waters in the Southern Hemisphere:[8]
- Callorhinchus callorynchus resides off southern South American waters, ranging from Tierra del Fuego north to Peru (in the Pacific) and southern Brazil (in the Atlantic). It is fished for year-round in the waters off of Brazil and Argentina.[9]
- Callorhinchus capensis is found in the oceans off southern Africa, including Namibia and South Africa.[10]
- estuaries and inshore bays to mate.[5]
Physiology
The encephalization quotient is 1.1, compared to 6 in humans. [11] Compared to humans, it has a larger cerebellum than forebrain. Its vision is very poor and the electrical sensing capabilities of the snout are predominantly used to find food. Both its circulatory and endocrine systems are similar to similar vertebrates, likely due to the early homologous structures the Callorhinchidae possess relative to the other Chondrichthyes.[12]
Diet
The Callorhinchidae are predominantly filter feeders, feeding on the sandy sediment of the ocean bottoms or continental shelves. The large protrusion of the snout aids in this task. Their diet consists of molluscs, more specifically, clams. Besides this, the Callorhinchidae have been shown to also feed on invertebrates such as jellyfish or small octopuses. They are considered to be incapable of eating bony fish, in that they cannot keep up with the teleosts' speed.[13]
Reproduction
The Callorhinchidae are
Species
The family contains three
- Callorhinchus callorynchus Linnaeus, 1758 (Ploughnose chimaera, American elephantfish, or cockfish)
- A. H. A. Duméril, 1865 (Cape elephantfish)
- Bory de Saint-Vincent, 1823 (Australian ghostshark)
A number of fossil species are also known, extending back into the mid-Cretaceous (Albian).[15]
Fishery and conservation effort
Currently, no effort is being made to conserve the family Callorhinchidae, but the species are heavily fished for food in South America. Because of this, they are extremely susceptible to being overfished.[
References
- ^ ISBN 0-12-547665-5.
- ^ "Family Callorhynchidae". Fossilworks. Retrieved 17 December 2021.
- ^ a b Froese, Rainer, and Daniel Pauly, eds. (2009). "Callorhincidae" in FishBase. January 2009 version.
- ^ "Elephant Fish: Callorhinchus Milii". Fish Index. Retrieved 8 October 2013.
- ^ a b Bester, Cathleen. "Biological Profile: Ghost Shark". Florida Museum of Natural History. Retrieved 8 October 2013.
- ^ a b "Elephant Shark Genome Sequencing". Archived from the original on 2018-04-11. Retrieved 2013-10-29.
- ^ "Chimaerids, elephant fish and ghost sharks". Sea Friends. Retrieved 8 October 2013.
- ISBN 978-0-9941041-6-8.
- ^ a b Dagit, D.D.; Chiaramonte, G.E.; Romero, M.; Di Giácomo, E.; Acuña, E. (2018) [errata version of 2007 assessment]. "Callorhinchus callorynchus". IUCN Red List of Threatened Species. 2007: e.T63107A133966405. Retrieved 19 January 2020.
- ISBN 978-1-77007-772-0
- ^ Kara E. Yopak, Thomas J. Lisney, Shaun P. Collin, John C. Montgomery; Variation in Brain Organization and Cerebellar Foliation in Chondrichthyans: Sharks and Holocephalans. Brain Behav Evol 1 April 2007; 69 (4): 280–300. https://doi.org/10.1159/000100037
- ^ Warren, Wes. "Genome: Callorhinchus milii". The Genome Institute at Washington University. Archived from the original on 3 November 2013. Retrieved 28 September 2013.
- ^ Wilson, Judith. "Elephant Sharks". Critters. Retrieved 28 October 2013.
- ^ Powell, Arthur. "Elephant Fish". Encyclopedia of New Zealand. Retrieved 28 September 2013.
- S2CID 111377431.
- ^ "Best Fish Guide:Elephant Fish". Forest and Bird. Retrieved 28 September 2013.