Coffin ray

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Coffin ray

Least Concern  (IUCN 3.1)[1]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Superorder: Batoidea
Order: Torpediniformes
Family: Hypnidae
T. N. Gill
, 1862
Genus: Hypnos
A. H. A. Duméril
, 1852
Species:
H. monopterygius
Binomial name
Hypnos monopterygius
(G. Shaw, 1795)
Range of the coffin ray[1]
Synonyms

Hypnos subnigrum Duméril, 1852
Lophius monopterygius Shaw, 1795

Hypnos monopterygius, also known as the coffin ray or Australian numbfish, is a

caudal fins all concentrated towards the rear, give the coffin ray a distinctive pear
-like shape. It is a varying shade of brown in colour above, and has tiny eyes and a large, highly distensible mouth.

The sluggish and

Least Concern
, as its population does not seem threatened by human activity.

Taxonomy and phylogeny

The first scientific reference to the coffin ray was written by English

junior synonym.[4]

The common name "coffin ray" comes from the

Phylogenetic studies, based on morphology, have found that Hypnos is most closely related to the genus Torpedo. Hence, some taxonomists classify it with Torpedo in the family Torpedinidae (in its own subfamily, Hypninae). On the other hand, there are also taxonomists who believe Hypnos to be distinctive enough to merit its own separate family, Hypnidae.[5][7]

Distribution and habitat

The coffin ray has a wide but

estuaries, and bays, and can also be found over seagrass as well as on and around rocky and coral reefs.[9][10]

Description

The coffin ray can be identified by its greatly enlarged pectoral fin disc and tiny tail.

The unusual pear-like shape of the coffin ray distinguishes it from all other rays. Its body is flabby, with two large, kidney-shaped

pectoral fins form a greatly enlarged disc about as wide as long, that is thick at the center and thin at the margins. The leading margin of the disc is straight to gently concave. The eyes are minute and can be elevated on short stalks. Close behind the eyes and slightly larger are the spiracles, which are rimmed by small papillae in some individuals. The nostrils are located just ahead of the mouth, and are connected to it by a pair of broad grooves. Between the nostrils is a short curtain of skin that overlaps the mouth. The capacious mouth forms a very long, wide arch; the slender jaws can be distended dramatically, though are not particularly protrusible. Adults have over 60 rows of small teeth in either jaw; each tooth has three long cusps. The five pairs of gill slits are small and placed beneath the disc.[5][9]

The

dermal denticles, and may be creased in areas. The dorsal colouration ranges from dark to reddish brown, to grayish, pinkish, or yellowish, and may be plain or sparsely patterned with irregular darker and lighter markings. The underside is pale, as are the spiracle papillae.[5][9] This species grows to a length of 70 cm (28 in), or possibly even 92 cm (36 in), though most are only around 40 cm (16 in) long.[6][9]

Biology and ecology

Coffin rays are often stranded on the shore.

The coffin ray is a slow and weak swimmer that moves forward with a jerky, fluttery motion. It is

predators.[4][10]

The diet of the coffin ray consists mostly of

tapeworms Acanthobothrium angelae[14] and Lacistorhynchus dollfusi,[15] and the nematode Echinocephalus overstreeti.[16]

They are preyed upon by tiger sharks. One large tiger shark caught at Port Stephens in the early 20th century had more than thirty of them in its stomach.[8]

Human interactions

When approached, the coffin ray tends to keep still in its place of concealment on the

sea floor. As a result, many divers, swimmers, and bathers have been shocked after accidentally contacting it.[9][12] While not life-threatening, the shock can be quite severe; strong enough to numb a human limb for several minutes[17] or knock a standing adult human off his feet.[18] The shock can still be perceived by a person pouring a stream of seawater on the ray,[5] or handling a net in which a coffin ray is held. The fish is capable of issuing multiple shocks in a short period of time, though each shock is weaker than the last.[17]

In 1883,

Least Concern.[1] It has been kept in public aquariums, but requires moving food.[13]

References

  1. ^
    doi:10.2305/IUCN.UK.2015-4.RLTS.T41828A68630121.en
    . Retrieved 12 November 2021.
  2. ^ Shaw, G. & Nodder, F.P. (1789–1813). The Naturalist's Miscellany. Plates 202–203.
  3. ^ Duméril, A.H.A. (1852). "Monographie de la famille des torpédiniens, ou poissons plagiostomes électriques, comprenant la description d'un genre nouveau, de 3 espèces nouvelles, et de 2 espèces nommées dans le Musée de Paris, mais non encore décrites". Revue et Magasin de Zoologie. (Sér. 2). 4: 176–189, 227–244, 270–285.
  4. ^ a b Bigelow, H.B.; Schroeder, W.C. (1953). Fishes of the Western North Atlantic, Part 2. Sears Foundation for Marine Research, Yale University. pp. 80–96.
  5. ^
    ISBN 978-0-674-03411-2
    .
  6. ^ a b c Froese, Rainer; Pauly, Daniel (eds.) (2015). "Hypnos monopterygius" in FishBase. April 2015 version.
  7. ISBN 0-8493-1514-X
    .
  8. ^ a b "THE NUMB-FISH". Telegraph (Brisbane, Qld. : 1872 - 1947). 10 April 1937. p. 20. Retrieved 17 July 2021.
  9. ^
    ISBN 92-5-104302-7
    .
  10. ^
    ISBN 0-930118-18-9
    .
  11. ^ Bray, D.J. (2011): Coffin Ray, Hypnos monopterygius, in Fishes of Australia, http://www.fishesofaustralia.net.au/home/species/1843 Archived 11 May 2013 at the Wayback Machine
  12. ^ a b Murch, A. Coffin Ray. Elasmodiver.com.
  13. ^ a b McGrouther, M. (2011): Numbfish, Hypnos monopterygium (Shaw & Nodder 1795). Australian Museum.
  14. doi:10.1071/IT01004
    .
  15. ^ Beveridge, I.; Sakanari, J.A. (1987). "Lacistorhynchus dollfusi sp. nov.(Cestoda: Trypanorhyncha) in elasmobranch fishes from Australian and North American coastal waters". Transactions of the Royal Society of South Australia. 111 (3–4): 147–154.
  16. ^ Beveridge, I. (1987). "Echinocephalus overstreeti Deardorff & Ko, 1983 (Nematoda: Gnathostomatoidea) from elasmobranchs and molluscs in South Australia". Transactions of the Royal Society of South Australia. 3 (1–2): 79–92.
  17. ^ a b "Seascraps NUMB-FISH". Queensland Times (Ipswich, Qld. : 1909 - 1954). 22 May 1953. p. 6. Retrieved 17 July 2021.
  18. ^ "THE TORPEDO OR NUMB FISH". Evening News (Sydney, NSW : 1869 - 1931). 13 May 1905. p. 9. Retrieved 17 July 2021.
  19. ^ Ramsay, E.P. (1883). Notes on the food fishes and edible mollusca of New South Wales, etc., etc., exhibited in the New South Wales Court. W. Clowes and Sons. p. 33.

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