Torpedo mackayana

Torpedo mackayana, commonly known as the ringed torpedo,[2] Western African torpedo,[3] West African torpedo ray,[1] McKay electric ray,[4] or McKay's torpedo ray,[5] is an electric ray species in the family Torpedinidae, which lives in shallow waters on the western coast of Africa. Characterized by rounded spiracles and white and brown spots, females grow to 35–50 centimetres (14–20 in) and males to 31.5–38.2 centimetres (12.4–15.0 in).

Torpedo mackayana
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Chondrichthyes
Subclass:
Elasmobranchii
Order:
Torpediniformes
Family:
Torpedinidae
Genus:
Torpedo
Species:
T. mackayana
Binomial name
Torpedo mackayana
Metzelaar, 1919

Taxonomy

Torpedo mackayana was described in 1919 by Jan Metzelaar (1891–1929), a Dutch biologist.[2]

Description

Torpedo mackayana has a round, "fleshy" disc, which has a slightly greater width than length. It has a gray-brown or rusty-brown upperside and a white underside.[3] It is covered with small patches of brown or white.[4] These patches may differ significantly in size and distribution throughout its body. It has a long, strong tail and two dorsal fins. The first dorsal fin is broad, while the second is slightly smaller and more slender. Its teeth are distributed in up to 38 rows and it has visible flaps on its nostrils. It has rounded spiracles, a feature that does not appear in any other species in the genus Torpedo.[3]

Torpedo mackayana is a small to medium-sized ray.[3] Its growth and size was surveyed in the Coast of Senegal from 1994 to 1998, with the results having been published in 2001. This study showed that it has an average length of about 9.55 centimetres (3.76 in) and an average weight of 20.64 grams (0.728 oz) at birth. Females typically reach sexual maturity at about 35 centimetres (14 in) and males reach it at 31.5 centimetres (12.4 in). As an adult, females are larger than males. According to the survey, the length of adult females is 35–50 centimetres (14–20 in) and the length of adult males is 31.5–38.2 centimetres (12.4–15.0 in). The largest female observed weighed 2,010 grams (71 oz) and the largest male weighed 1,255 grams (44.3 oz).[5]

Ecology

The reproductive cycle of Torpedo mackayana can take a year, and gestation can take nearly half a year. Ovulation happens in May or June, and young are born in August or September. Like other species in the genus Torpedo, the oocyte of the species is sometimes prevented from growing until birth. Females have two uteri and two ovaries. The eggs of the species, when fertilized, weigh about 8.6 grams (0.30 oz) on average, and the oocytes weigh an average of 9.2 grams (0.32 oz).[5]

Torpedo mackayana has a coastal habitat and lives in depths of 30–50 metres (98–164 ft).[4] It has been found in estuaries and on sea floors of mud or sand.[1] Its prey consists of fish and smaller invertebrates. Little else is known about its biology.[3]

Distribution and conservation

Torpedo mackayana lives in tropical waters of the eastern Atlantic Ocean,[6] in 16 countries on the western coast of Africa. The most northern part of its range is Senegal, and the most southern part is Angola. It is likely caught by fisheries as a bycatch. Pollution and habitat destruction, due to coastal development, are also threats in part of its range. However, nothing is known about its population size or trend, except that it is not severely threatened.[1] The adult population consists of more females than males, while young are more commonly male than female.[5] No conservation actions are taking place for the species, and it is listed as data deficient on the IUCN Red List as of 2007. According to the IUCN, further research is required of the species' population before planning conservation actions.[1]

References
  1. Pheeha, S.; Cronin, E. S. (2009). "Torpedo mackayana (West African Torpedo Ray)". The IUCN Red List of Threatened Species. doi:10.2305/IUCN.UK.2009-2.RLTS.T161411A5418113.en.
  2. Watkins, Michael; Beolens, Bo (January 3, 2015). Sharks: An Eponym Dictionary. Pelagic Publishing Ltd. p. 106. ISBN 1784270377. Retrieved 20 February 2019.
  3. Last, Peter; Naylor, Gavin; Séret, Bernard; White, William; de Carvalho, Marcelo; Stehmann, Matthias (2016). Rays of the World. Csiro Publishing. p. 198. ISBN 0643109145. Retrieved 20 February 2019.
  4. Seret, Bernard (2006). Identification Guide of the Main Shark and Ray Species of the Eastern Tropical Atlantic: For the Purpose of the Fishery Observers and Biologists (PDF). FIBA. p. 55. ISBN 2951491492. Retrieved 19 February 2019.
  5. Capapé, Christian; Seck, A. A.; Diatta, Y.; Diop, Melissa (March 2001). "Observations on the reproductive biology of Torpedo (Tetronarce) mackayana (Torpedinidae), from the coast of Senegal (eastern tropical Atlantic)". Cybium. 1 (25): 95–99. Retrieved 19 February 2019.
  6. Carrier, Jeffrey C.; Musick, John A.; Heithaus, Michael R. (March 9, 2010). Sharks and Their Relatives II: Biodiversity, Adaptive Physiology, and Conservation (illustrated ed.). CRC Press. p. 225. ISBN 1420080482. Retrieved 20 February 2019.
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