Frilled shark

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Frilled shark
Temporal range: Pleistocene – Holocene
↓
At the Palais de la Porte Dorée

Least Concern  (IUCN 3.1)[1]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Subdivision: Selachimorpha
Order: Hexanchiformes
Family: Chlamydoselachidae
Genus: Chlamydoselachus
Species:
C. anguineus
Binomial name
Chlamydoselachus anguineus
World map indicating the habitats (blue) in the mid–Atlantic Ocean, and in the Pacific Ocean, ranging from Japan to Australia to California
Range of the frilled shark
Closer view of the head

The frilled shark (Chlamydoselachus anguineus), also known as the lizard shark, is one of the two

anal fins located towards the tail. The common name, frilled shark, derives from the fringed appearance of the six pairs of gill slits
at the shark's throat.

The two species of frilled shark are distributed throughout regions of the

bony fish, the frilled shark practices diel vertical migration to feed at night at the surface of the ocean. When hunting food, the frilled shark curls its tail against a rock and moves like an eel, bending and lunging to capture and swallow whole prey with its long and flexible jaws, which are equipped with 300 recurved, needle-like teeth.[2]

Reproductively, the two species of frilled shark, C. anguineus and C. africana, are

fishmeal; and has been caught from depths of 1,570 m (5,150 ft), although its occurrence is uncommon below 1,200 m (3,900 ft); whereas in Suruga Bay, Japan, the frilled shark commonly occurs at depths of 50–200 m (160–660 ft).[3]

Taxonomy and phylogeny

The zoologist Ludwig Döderlein first identified, described, and classified the frilled shark as a discrete species of shark. After three years (1879–1881) of marine research in Japan, Döderlein took two specimen sharks to Vienna, but lost the taxonomic manuscript of the research. Three years later, in the Bulletin of the Essex Institute (vol. XVI, 1884) the zoologist Samuel Garman published the first taxonomy of the frilled shark, based upon his observations, measurements, and descriptions of a 1.5-metre (4 ft 11 in)–long female shark from Sagami Bay, Japan. In the article "An Extraordinary Shark" Garman classified the new species of shark within its own genus and family, and named it Chlamydoselachus anguineus (eel-like shark with frills).[4][5] The Graeco–Latin nomenclature of the frilled shark derives from the Greek chlamy (frill) and selachus (shark), and the Latin anguineus (like an eel);[2] besides its common name, the frilled shark also is known as the "lizard shark" and as the "scaffold shark".[1][6]

In the article "An Extraordinary Shark", the zoologist Samuel Garman depicts a frilled shark (Clamydoselachus anguineus); the superior inset depicts dorsal and ventral views of the shark's head; the inferior inset depicts two, trident-shaped teeth. (Bulletin of the Essex Institute, vol. XVI, 1884)

The frilled-shark is considered a "living fossil", because its family lineage dates to the

Mesozoic era (252–66 mya); and Cope categorized the Chlamydoselachus anguineus species to the fossil genus Xenacanthus that existed from the late Devonian period to the end of the Triassic period of the Mesozoic era.[9][10]

The anatomic traits of body, muscle, and skeleton phylogenically include the frilled shark to the neoselachian clade (modern sharks and rays) which relates it to the cow shark, in the order Hexanchiformes. In addition, a genetic analysis conducted by researchers in 2016 may also suggest that the species is part of the order Hexanchiformes.[11] Nonetheless, as a systematist of biology, the ichthyologist Shigeru Shirai proposed the Chlamydoselachiformes taxonomic order exclusively for the C. anguinesis and the C. africana species of frilled sharks.[8][10] As a marine animal, the frilled shark is a living fossil because of its relatively unchanged anatomy and physique, since first appearing in the primeval seas of the Late Cretaceous (c. 95 mya) and the Late Jurassic (150 mya) epochs.[12][5] In evolutionary terms, the frilled shark is an animal species of recent occurrence in the natural history of the Earth; the earliest discoveries of the fossilized teeth of the Chlamydoselachus anguineus species of shark date to the early Pleistocene epoch (2.58–0.0117 mya).[13] In 2009, marine biologists identified, described, and classified the Chlamydoselachus africana (southern African frilled shark) of the Atlantic waters of southern Angola and of southern Namibia as a species of frilled shark different from the Chlamydoselachus anguineus identified in 1884.[14]

Habitat and distribution

A shark swimming in fart in water over sand; the data label indicates that the image was taken on August 26, 2004, at a depth of 2,866 ft., a temperature of 4.3°C, and a salinity of 35.
A frilled shark in its Blake Plateau habitat, in the western Atlantic Ocean. (2004)

The habitats of the frilled shark include the waters of the outer

bony fish, indicates that the frilled shark practices diel vertical migration, and swims up to feed at night at the surface of the ocean.[15][2] In their Atlantic- and Pacific-ocean habitats, frilled sharks practice spatial segregation determined by the individual size, the sex, and the reproductive condition of each shark in the shiver.[16] In Suruga Bay, on the Pacific coast of Honshu, Japan, the frilled shark is most common at the depth of 50–200 m (160–660 ft), except in the August-to-November period, when the temperature at the 100 m (330 ft) water-layer exceeds 15 °C (59 °F), and then the sharks swim into deeper, cooler water.[17][16]

The habitats (blue) of the Chlamydoselachus anguineus and the Chlamydoselachus africana species of frilled shark are distributed throughout the Atlantic Ocean and the Pacific Ocean, ranging from Japan to Australia to North America to Africa.

In the eastern Atlantic Ocean, the frilled shark occurs off northern Norway, northern Scotland, and western Ireland, ranging from France to Morocco, the archipelago of Madeira, and the coast of Mauritania, in northwest Africa.[18] In the central Atlantic Ocean, the frilled shark has been caught along the region of the Mid-Atlantic Ridge, ranging from north of the Azores islands to the Rio Grande Rise, off southern Brazil, and the Vavilov Ridge, off West Africa. Frilled sharks tend to be very solitary organisms; interacting with multiple individuals of their kind is rare. However, in the late 2000s a large capture was made over an underwater seamount of the Mid-Atlantic Ridge, hauling in over 30 frilled sharks. The mass capture of a wide variety of male and female specimens emphasized these seamounts as a location for the mating of the species.[19] In the western Atlantic, the frilled shark occurs in the waters of New England and Georgia, in the US, and in the waters of Suriname, in the northeastern coast of South America.[20][19][14]

In the western Pacific Ocean, the frilled shark ranges from southeastern Honshu, Japan, north to Taiwan, off the coast of China, to the coast of New South Wales, Australia, and the islands of Tasmania and New Zealand. In the central and eastern Pacific Ocean, the frilled shark occurs in the regional waters of Hawaii and the coast of California, in the US, and the northern coast of Chile, in western South America.[1][18] Although it has been caught at the depth of 1,570 m (5,150 ft), the frilled shark usually does not occur deeper than 1,000 m (3,300 ft).[1][6]

Description

The frilled shark's lower jaw has 21–29 rows of recurved, needle-like teeth, for snagging, capturing, and eating soft-bodied cephalopods, small sharks, and bony fish.

The eel-like bodies of C. anguineus and C. africana differ anatomically; C. anguineus has a longer head and shorter gill slits, a spinal column with more vertebrae (160–171 vs. 147), and a lower-intestine spiral valve with more turns (35–49 vs. 26–28) than does C. africana.[14] The skin color of either species ranges from uniformly dark-brown to uniformly grey.[2] In addition, C. anguineus has smaller pectoral fins than C. africana, and the mouth is narrower.[21] The recorded, maximum body-length of a male frilled shark is 1.7 m (5.6 ft), and the recorded, maximum body-length of a female frilled shark is 2.0 m (6.6 ft).[2]

The frilled shark name of the Chlamydoselachus anguineus species derives from the extended tips of the gill filaments of the shark's six pairs of gills.
The jaws of the frilled shark are able to open very wide in order to engulf larger prey.

The head of the frilled shark is broad and flat, with a short, rounded snout. The

gill filaments create a fleshy frill, hence, the frilled shark name of this fish.[4]

The

dermal denticles, which the shark can enlarge.[4] The underside of the shark's eel-like body features a pair of long, thick folds of skin, separated by a groove, which run the length of the belly; the function of the ventral skin-folds is unknown.[4] In the female frilled shark, the mid-section is of the body longer, with the pelvic fins located closer to the anal fin.[15][22]

Biology and ecology

A cartilaginous skeleton and a large

predators, such as other sharks, as indicated by missing tail-tips lost to a hungry attacker.[16]

In New Zealand, the

mass-extinction event which occurred at the Cretaceous–Paleogene time-boundary, one hypothesis proposes that the sharks survived in bodies of shallow water, both inland and on the continental shelf; afterwards, the frilled shark migrated to deep-water habitats.[27]

Diet

The frilled shark eats a diet of

bony fish;[2] 60 percent of the diet is composed of squid varieties, such as the Chiroteuthis, the Histioteuthis, and the Onychoteuthis, the Sthenoteuthis and the Todarodes;[17] and other sharks, as indicated by the stomach contents of a 1.6 m (5.2 ft)–long frilled shark which had swallowed a 590 g (1.30 lb) Japanese catshark (Apristurus japonicus).[15] The high tendency to primarily consume the squids in their habitat can be supported by the frequent observation of beak remnants left behind during digestive processes.[17] Because frilled sharks live on the ocean floor, they may also feed on carrion floating down from the surface.[28]

The head of a preserved shark, with the large mouth open
The frilled shark is a predator with long jaws directly articulated to the cranium, at a point behind the eyes.

In hunting and eating prey that are tired or exhausted or dying (after spawn),[17] the frilled shark's physiology suggests that it may curve its anguilline body, and brace its rear fins against the water, for leverage to effect a rapid-strike bite that captures the prey.[15] The wide gape of the distended, long jaws allows devouring whole prey that are more than half the size of the frilled shark, itself.[2] The jaws' 300 recurved teeth (19–28 upper rows and 21–29 lower rows) readily snag and capture the soft body and tentacles of a cephalopod, especially with the rows of trident-shaped teeth are rotated outwards, when the jaws are open and protruded.[4] Moreover, unlike the strong bite of sharks with an underslung jaw attached below the cranium,[29] the frilled shark has a relatively weak bite, because of the limited leverage and force possible with long jaws that are directly articulated to the cranium, at a point behind the eyes.[29]

The behavior of captive specimen sharks suggests that the frilled shark also hunts with its mouth open, by using the dark-and-light contrast of white teeth and darkness to lure prey into its gaping maw;[14] and also hunts with negative pressure, to suck prey into its maw.[15] Forensic examination of frilled sharks' revealed little-to-no food in their stomachs, which suggests that the frilled shark either has a fast-rate of digestion or goes hungry in the long intervals between feedings.[17]

Reproduction

The extant species of frilled shark, C. anguineus and C. africana, do not have a defined breeding season, because their oceanic habitats register no seasonal influence from the ocean's surface;[16] the male shark reaches sexual maturity when he is 1.0–1.2 m (3.3–3.9 ft) long, and the female shark reaches sexual maturity when she is 1.3–1.5 m (4.3–4.9 ft) long.[1] The mature female shark has two ovaries and a uterus, which is in the right side of her body; ovulation occurs fortnightly; and pregnancy ceases vitellogenesis (yolk formation) and the production of new ova.[16] Both ovulated eggs and early-stage shark embryos are enclosed in chondrichthyes, ellipsoid egg-cases made of a thin, golden-brown membrane.[2]

Reproductively, the frilled shark is an

gestation period can be as long as 3.5 years;[16][15] at birth, a frilled shark's litter comprises 2–15 pups, with an average litter comprises 6.0 pups.[2]

Shark and human interaction

In pursuit of food, the frilled shark usually is a

fishmeal and as meat.[16]

In 2004,

Commonwealth Scientific and Industrial Research Organisation (CSIRO) confirmed that the shark was a Chlamydoselachus anguineus, an eel-like shark with a frill.[33]

In 2016, consequent to the depletion of food sources caused by commercial overfishing of the

Least Concern of extinction.[1] In 2018, the New Zealand Threat Classification System identified the frilled shark as an animal "At Risk — Naturally Uncommon", not easily found living in the wild.[34]

See also

References

  1. ^
    doi:10.2305/IUCN.UK.2016-1.RLTS.T41794A68617785.en
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  2. ^
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  3. ^ Bray, Dianne J. (2011). "Frill Shark, Chlamydoselachus anguineus". FishesofAustralia.net.au. Archived from the original on 10 October 2014. Retrieved 7 October 2014.
  4. ^ a b c d e f Garman, S. (January 17, 1884). "An Extraordinary Shark". Bulletin of the Essex Institute. 16: 47–55.
  5. ^
    ISBN 0-8117-2875-7
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  6. ^ a b Froese, Rainer; Pauly, Daniel (eds.) (2010). "Chlamydoselachus anguineus" in FishBase. April 2010 version.
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    doi:10.1093/icb/17.2.303
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  10. ^ a b Martin, R.A. Chlamydoselachiformes: Frilled Sharks. ReefQuest Centre for Shark Research. Retrieved on April 25, 2010.
  11. PMID 33473392
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  12. ^ Martin, R.A. The Rise of Modern Sharks. ReefQuest Centre for Shark Research. Retrieved on April 25, 2010.
  13. ^ Marsili, S. (2007). Analisi systematic, paleoecological e paleobiogeographical Della selaciofauna polio-Pleistocene del Mediterraneo.
  14. ^
    doi:10.11646/zootaxa.2173.1.1
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  15. ^ a b c d e f g h i Martin, R.A. Deep Sea: Frilled Shark. ReefQuest Centre for Shark Research. Retrieved on April 25, 2010.
  16. ^ a b c d e f g h Tanaka, S.; Shiobara, Y.; Hioki, S.; Abe, H.; Nishi, G.; Yano, K. & Suzuki, K. (1990). "The reproductive biology of the frilled shark, Chlamydoselachus anguineus, from Suruga Bay, Japan". Japanese Journal of Ichthyology. 37 (3): 273–291.
  17. ^
    doi:10.2331/suisan.57.15
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  18. ^
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  20. ^ a b Jenner, J. (2004). Estuary to the Abyss: Excitement, Realities, and "Bubba". NOAA Ocean Explorer. Retrieved on April 25, 2010.
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    doi:10.5281/zenodo.189264
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  23. ^ Martin, R.A. Hearing and Vibration Detection. ReefQuest Centre for Shark Research. Retrieved on April 25, 2010.
  24. ^ Collett, R. (1897). "On Chlamydoselacnus anguineus Garman. A remarkable shark found in Norway 1896". Christiania. 11: 1–17.
  25. ^ Machida, M.; Ogawa, K. & Okiyama, M. (1982). "A new nematode (Spirurida, Physalopteridae) from frill shark of Japan". Bulletin of the National Science Museum Series A (Zoology). 8 (1): 1–5.
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  27. S2CID 130714866.{{cite journal}}: CS1 maint: multiple names: authors list (link
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  28. ^ Lashaway, Aubrey. "ADW: Chlamydoselachus anguineus: INFORMATION". Animaldiversity.org. Retrieved 2022-08-23.
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  31. ^ Nishikawa, T. (1898). "Notes on some embryos of Chlamydoselachus anguineus, Garm". Annotationes Zoologicae Japonenses. 2: 95–102.
  32. ^ Japanese Marine Park Captures Rare 'Living Fossil' Frilled Shark; Pictures of a Live Specimen 'Extremely Rare'. Underwatertimes.com. January 24, 2007. Retrieved on April 25, 2010.
  33. ^ "'Horrific' Rarely-sighted Frilled Shark Caught off south-east Victoria". The Age. Melbourne, Australia: Fairfax Media. 21 January 2015. Retrieved 21 January 2015.
  34. OCLC 1042901090
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