Californian big-headed shark [1] ( Latin Cephalurus cephalus ) is a poorly studied and only described species of the genus of large-headed sharks ( Cephalurus ), a family of cat sharks ( Scyliorhinidae ). This little shark lives on the outer continental shelf . Outwardly, it resembles a tadpole. A large head with large gills allows it to adapt to living in an environment with a low oxygen content. Propagated by laying eggs. The diet consists of cephalopods , crustaceans, and small fish [2] .
| California big-headed shark |
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| Scientific classification |
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| No rank : | Bilateral symmetrical |
| Gender: | Big-headed sharks ( Cephalurus Bigelow & Schroeder , 1941 ) |
| View: | California big-headed shark |
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| International scientific name |
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Cephalurus cephalus ( Gilbert , 1892) |
| Synonyms |
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Catulus cephalus gilbert, 1892 |
| Area |
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| Security status |
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Not enough data IUCN Data Deficient : 161455 |
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Content
The first scientific description of a California big-headed shark called Catulus cephalus was published in 1892 by the American ichthyologist Charles Henry Gilbert in the scientific publication Proceedings of the United States National Museum . The described specimen was an adult male 24 cm long, caught off the coast of Clarion Island (a group of Revilla-Hikhedo islands ) [3] . In 1941, Henry Bigelow and William Schroeder created for this species a separate genus of large-headed sharks, Cephalurus [4] . Perhaps the existence of undescribed species of large-headed sharks off the coast of Panama , Chile and Peru , which differ little from the California large-headed shark in size and appearance [3] . The name of the genus comes from the words Greek. κεφάλι - “head” and other Greek. αἴλουρος - “cat”. Species epithet comes from the word Greek. κεφάλι - “head”.
Based on morphological and phylogenetic data, it is believed that the California big-headed shark forms a single treasure along with Australian spotted feline sharks , feline sharks, parmaturus , sawtails and black feline sharks . However, some authors disagree with the relationship within the group; molecular studies support the assumption of the kinship of big-headed sharks and feline sharks-parmaturus [5] .
California big-headed sharks live from the Gulf of California to Baja California at a depth of 155–937 [3] .
The California- headed shark got its name due to the specific shape of the body resembling a tadpole : it has a very large head and gill zone with a thin, cylindrical body tapering to the tail [3] . The head is wide, flattened and rounded; its length is 1/3 of the total body length. The muzzle is very short and dull. The nostrils are widely spaced and framed by skin folds. At the corners of the mouth there are grooves that twist to the upper and lower jaw. The teeth are widely spaced, have one central tip and 1-3 lateral teeth. There are numerous papillae on the tongue and palate; inside the mouth lies a light membrane. The eyes are large, oval. Five pairs of gill slits are clearly visible and curved in the form of an arch towards the head [3] [6] .
California large-headed sharks have a very soft, almost jelly-like body [3] . Unlike other cat sharks, the first dorsal fin is shifted forward relative to the ventral fins significantly more than the second. The second dorsal fin is almost equal in length to the first dorsal fin and only slightly inferior in height to it. It is located above the anal fin. The length of the pectoral fins is almost 2 times their width, their base is located under the fourth branchial fissure. Anal fin larger than second dorsal fin. The caudal fin has a well-developed lower lobe and a small ventral notch at the tip of the upper lobe [4] [6] . The skin is thin, loosely covered with plakoid scales alternating with narrower skin teeth resembling bristles, the density of which increases on the back [4] . The color is even gray-brown, sometimes the edges of the fins have a light edging. Eyes of iridescent green color [6] . The length of adult sharks is on average 24 cm. The maximum length is 28 cm [3] .
The large head and gill area suggest that these sharks are adapted to live at great depths, where there is little dissolved oxygen in the water. The diet consists mainly of crustaceans and fish. This species is propagated by placental live birth. Newborns about 10 cm long are born every summer. Females have two functional ovaries and bear a pair of thin-walled capsules (one in each oviduct) inside their body before delivery [7] . In males, puberty occurs at a length of 19 cm, and in females 24 cm [2] .
Sometimes these sharks fall into the net by- catch quality, but the great depth at which they live serves to some extent their protection. Data to assess the conservation status of this species is not enough [2] .
- ↑ Reshetnikov Yu.S. , Kotlyar A.N. , Russ T.S. , Shatunovsky M.I. The Bilingual Dictionary of Animal Names. Fish. Latin, Russian, English, German, French. / edited by Acad. V. E. Sokolova . - M .: Rus. Yaz., 1989 .-- P. 25 .-- 12,500 copies. - ISBN 5-200-00237-0 .
- ↑ 1 2 3 Cephalurus cephalus (English) . The IUCN Red List of Threatened Species .
- ↑ 1 2 3 4 5 6 7 Compagno, Leonard JV Sharks of the World: An Annotated and Illustrated Catalog of Shark Species Known to Date. - Rome: Food and Agricultural Organization, 1984. - P. 306-306. - ISBN 92-5-101384-5 .
- ↑ 1 2 3 Bigelow, HB and WC Schroeder. Cephalurus , a New Genus of Scyliorhinid Shark with Redescription of the Genotype, Catulus cephalus Gilbert. - Copeia, 1941 .-- P. 73-76. - DOI : 10.2307 / 1437434 .
- ↑ Iglésias, SP, G. Lecointre and DY Sellos. "Extensive paraphylies within sharks of the order Carcharhiniformes inferred from nuclear and mitochondrial genes." // Molecular Phylogenetics and Evolution. - 2005. - Issue. 34 . - S. 569-583 . - DOI : 10.1016 / j.ympev.2004.10.0.022. . - PMID 15683930 .
- ↑ 1 2 3 Mathews, CP and MF Ruiz D. " Cephalurus cephalus , a Small Shark, Taken in the Northern Gulf of California, with a Description." - 1974. - Vol. 1974, No. (2) . - P. 556-560.
- ↑ Balart, EF, J. González-García and C. Villavicencio-Garayzar (2000). "Notes on the biology of Cephalurus cephalus and Parmaturus xaniurus (Chondrichthyes: Scyliorhinidae) from the west coast of Baja California Sur, México." Fishery Bulletin 98: P. 219-221
