Spiny butterfly ray

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Spiny butterfly ray
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Superorder: Batoidea
Order: Myliobatiformes
Family: Gymnuridae
Genus: Gymnura
Species:
G. altavela
Binomial name
Gymnura altavela
Range of the spiny butterfly ray
Synonyms

Pteroplatea binotata Lunel, 1879
Pteroplatea canariensis Valenciennes, 1843
Pteroplatea vaillantii Rochebrune, 1880
Pteroplatea valenciennii Duméril, 1865
Raja altavela Linnaeus, 1758
Raja maclura Lesueur, 1817

The spiny butterfly ray or giant butterfly ray (Gymnura altavela) is a species of

sympatric smooth butterfly ray (G. micrura) by the spine at the base of its tail and by a small tentacular structure on the margin of each spiracle. Slow-reproducing and valued for its meat, in recent decades its population has experienced a decline of over 30%, and it has become Critically Endangered in certain parts of its range.[1]

Distribution and habitat

Spiny butterfly rays prefer sandy habitat

This species has a patchy and discontinuous distribution in Atlantic tropical and warm-temperate waters. In the western Atlantic it is found from

brackish and coastal waters over soft sandy or muddy substrates, at a depth of 5–100 m (16–328 ft).[3] This ray is uncommon overall but can be locally abundant in suitable habitat.[1] Individuals may segregate by sex, with females usually staying in deeper water but moving inshore to breed.[4]

Description

The spiny butterfly ray has a very broad,

lower jaw. In both jaws there are 10–12 functional tooth rows with each dental band occupying 70% the width of the jaw. There is a tentacle-like structure on the inner posterior margin of each spiracle. The tail is short and slender, measuring a quarter the disk width, with upper and lower fin folds. There are one or more serrated spines at the base of the tail.[3][5]

The

denticles on the center of the disk.[5] The coloration is dark brown above, sometimes with small lighter or darker spots and blotches in a marbled pattern, and white below. Juveniles have pale crossbars on the tail.[3] The maximum reported size is 2.2 m (7 ft 3 in) disk width in the northwest Atlantic, though there are unsubstantiated reports of rays over 4 m (13 ft) off West Africa.[1] The maximum published weight is 60 kg (130 lb).[6]

Biology and ecology

Spiny butterfly ray buried in sand

In the western Atlantic, the spiny butterfly ray feeds on

lamellibranchs, and gastropods, in descending order of importance. Teleost fishes apparently become more important in the ray's diet with increasing size. An active predator, the ray typically approaches a prey item slowly before rapidly spinning around over it and striking the food with the leading edge of one of their pectoral fins. This behavior likely serves to stun the prey before capture, as the pectoral fins of butterfly rays contain a high proportion of red muscle and can deliver blows of substantial force.[7][8]

Potential predators of spiny butterfly rays include larger fish such as the

tapeworms Anthobothrium altavelae and Pterobothrioides petterae, and the gill parasite Heteronchocotyle gymnurae.[3][10][11]

Spiny butterfly rays are

oral cavity.[12] Litter size is up to 8, depending on geographical location: 4 per litter in the Gulf of Mexico, 1–6 in the Mediterranean, up to 5 off Brazil, and up to 8 in the northwest Atlantic. Females have one functional ovary (the left) and two functional uteruses, with the embryos evenly distributed in each one. The newborns measure 38–44 cm (15–17 in) across; their size is inversely related to the number of young in each uterus.[1][8] In the eastern Atlantic, males mature at around 78 cm (31 in) across and females at 108 cm (43 in). In the western Atlantic, males mature at around 102 cm (40 in) across and females at 155 cm (61 in).[7] Females mature later than males and reach a larger size.[4]

Relationship to humans

Spiny butterfly rays are harmless to humans, though if stepped on its tail spine can cause a painful wound. It is listed as a

Elsewhere in the spiny butterfly ray's range, it faces heavy fishing pressure, including in its coastal nursery areas, and has experienced marked declines. It is assessed as Critically Endangered in the southwest Atlantic, where it is taken by multispecies

artisan fishers and other observers from Mauritania to Guinea have reported a severe drop in abundance, as well as decreasing median size as the adults are removed.[1]

References

  1. ^
    doi:10.2305/IUCN.UK.2021-1.RLTS.T63153A3123409.en. Retrieved 20 November 2021.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  2. ^ Guide of Mediterranean Skates and Rays (Gymnura altavela). Oct. 2022. Mendez L., Bacquet A. and F. Briand. http://www.ciesm.org/Guide/skatesandrays/Gymnura-altavela
  3. ^ a b c d e f Conrath, C. and Scarbrough, R. Biological Profiles: Spiny Butterfly Ray. Florida Museum of Natural History Ichthyology Department. Retrieved on March 4, 2009.
  4. ^ a b Capapé, C.; Zaouali, J.; Tomasini, J.A. & Bouchereau, J.L. "Reproductive biology of the spiny butterfly ray, Gymnura altavela (Linnaeus, 1758) (Pisces: Gymnuridae) from off the Tunisian coasts". Scientia Marina. 56 (4): 347–355.
  5. ^ .
  6. ^ Froese, Rainer; Pauly, Daniel (eds.) (2009). "Gymnura altavela" in FishBase. March 2009 version.
  7. ^ .
  8. ^ .
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  11. .
  12. ^ Murch, A. Information about the Spiny Butterfly Ray. Elasmodiver.com. Retrieved on March 4, 2009.

External links