Batoidea

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Batoidea
Temporal range: Early Jurassic–Present [1]
Giant devil ray, Mobula mobular
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Clade:
Neoselachii
Superorder: Batoidea
Compagno, 1973
Orders
Synonyms
  • Batoidimorpha
  • Myliobatoidea
    ?
Spotted eagle ray, Aetobatus narinari

Batoidea is a

ventral
surfaces.

Anatomy

See also: Batoid locomotion

Batoids are flat-bodied, and, like sharks, are cartilaginous fish, meaning they have a boneless

anal fin is absent. The eyes and spiracles are located on top of the head. Batoids have a ventrally located mouth and can considerably protrude their upper jaw (palatoquadrate cartilage) away from the cranium to capture prey.[3] The jaws have euhyostylic type suspension, which relies completely on the hyomandibular cartilages for support.[4]
Bottom-dwelling batoids breathe by taking water in through the spiracles, rather than through the mouth as most fish do, and passing it outward through the gills.

Reproduction

Batoids reproduce in a number of ways. As is characteristic of elasmobranchs, batoids undergo

ovoviviparous, meaning that they give birth to young which develop in a womb but without involvement of a placenta.[6]

The eggs of oviparous skates are laid in leathery egg cases that are commonly known as

mermaid's purses
and which often wash up empty on beaches in areas where skates are common.

Capture-induced premature birth and abortion (collectively called capture-induced parturition) occurs frequently in sharks and rays when fished.[6] Capture-induced parturition is rarely considered in fisheries management despite being shown to occur in at least 12% of live bearing sharks and rays (88 species to date).[6]

Habitat

Most species live on the sea floor, in a variety of geographical regions – mainly in coastal waters, although some live in deep waters to at least 3,000 metres (9,800 ft). Most batoids have a cosmopolitan distribution, preferring tropical and subtropical marine environments, although there are temperate and cold-water species. Only a few species, like manta rays, live in the open sea, and only a few live in freshwater, while some batoids can live in brackish bays and estuaries.

Feeding

Most batoids have developed heavy, rounded teeth for crushing the shells of bottom-dwelling species such as

oysters, crustaceans, and some fish, depending on the species. Manta rays feed on plankton
.

Evolution

Batoids belong to the ancient lineage of cartilaginous fishes. Fossil

Neoselachii, emerged by the Triassic, with the best-understood neoselachian fossils dating from the Jurassic. The oldest confirmed ray is Antiquaobatis, from the Pliensbachian of Germany.[7] The clade is represented today by sharks, sawfish, rays and skates.[8]

Classification

The classification of batoids is currently undergoing revision; however, molecular evidence refutes the hypothesis that skates and rays are derived sharks.

basal or incertae sedis; they show features of the Rajiformes but have snouts resembling those of sawfishes. However, evidence indicates they are probably the sister group to sawfishes.[10]
Phylogenetic tree of Batoidea:[11]

Chondrichthyes

Holocephali (incl. Chimaera)

Elasmobranchii

Selachimorpha (Sharks)

Batoidea
Order Image Common name Family Genera Species Comment
Total
Myliobatiformes
Stingrays
and relatives 		10 29 223 1 16 33 [a][12]
Rajiformes Skates and relatives 5 36 270 4 12 26 [b]
Torpediniformes
 		Electric rays 4 12 69 2 9 [c][13]
Rhinopristiformes Shovelnose rays and relatives 1 2 5-7 3-5 2 [d][14]
Heliobatis radians

Order

Torpediniformes

Order Rhinopristiformes

  • Family
    Glaucostegidae
    (giant guitarfishes)
  • Family Platyrhinidae* (fanrays)
  • Family
    Pristidae
    (sawfishes)
  • Family
    Rhinidae
    (wedgefishes)
  • Family
    Rhinobatidae
    (guitarfishes)
  • Family Trygonorrhinidae (banjo rays)
  • Family
    Zanobatidae
    * (panrays)

* the placement of these families is uncertain

Order Rajiformes

Order Myliobatiformes

  • Family
    Aetobatidae
    (pelagic eagle rays)
  • Family
    Dasyatidae
    (whiptail stingrays)
  • Family
    Gymnuridae
    (butterfly rays)
  • Family
    Hexatrygonidae
    (sixgill stingrays)
  • Family
    Myliobatidae
    (devilrays)
  • Family
    Plesiobatidae
    (giant stingarees)
  • Family Potamotrygonidae (Neotropical stingrays)
  • Family
    Rhinopteridae
    (cownose rays)
  • Family Urolophidae (stingarees)
  • Family Urotrygonidae (round stingrays)

Conservation

See also: List of threatened rays

According to a 2021 study in Nature, the number of oceanic sharks and rays has declined globally by 71% over the preceding 50 years, jeopardising "the health of entire ocean ecosystems as well as food security for some of the world's poorest countries". Overfishing has increased the global extinction risk of these species to the point where three-quarters are now threatened with extinction.[15][16][17] This is notably the case in the Mediterranean Sea - most impacted by unregulated fishing - where a recent international survey of the Mediterranean Science Commission concluded that only 38 species of rays and skates still subsisted.[18]

Differences between sharks and rays

All sharks and rays are cartilaginous fish,

contrasting with bony fishes. Many rays are adapted for feeding on the bottom. Guitarfishes
are somewhat between sharks and rays, displaying characteristics of both (though they are classified as rays).

Comparison of Elasmobranchid fish
Characteristic Sharks
Guitar fish
 Rays
Shape
laterally
compressed spindle
dorsoventrally
compressed (flattened) disc
Spiracles not always present always present
Habitat usually
demersal bottom feeders
 demersal / pelagic mix usually demersal bottom feeders
Eyes usually at the side of the head usually on top of the head
Gill openings on the sides ventral (underneath)
Pectoral fins
 distinct not distinct
Tail large
caudal fin
whose primary function is to provide main forward propulsion 		varies from thick tail as extension of body to a whip that can sting to almost no tail.
Locomotion swim by moving their tail (
caudal fin
) from side to side 		Guitar fish and sawfish have a caudal fin like sharks swim by flapping their pectoral fins like wings

See also

Wikimedia Commons has media related to Batoidea.

Footnotes

  1. derived members evolved their highly flattened shapes independently of the skates.[12]
  2. mermaid's purse
    .
  3. ancient Greeks and Romans used these fish to treat ailments such as headaches.[13]
  4. pectoral fins than most batoids. The pectoral fins are attached above the gills as in all batoids, giving the fishes a broad-headed appearance. They have long, flat snouts with a row of tooth-like projections on either side. The snouts are up to 1.8 metres (6 ft) long, and 30 centimetres (1 ft) wide, and are used for slashing and impaling small fishes and to probe in the mud for embedded animals. Sawfishes can enter freshwater rivers and lakes. Some species reach a total length of 6 metres (20 ft). All species of sawfish are endangered or critically endangered.[14]

References

  1. PMID 22209858
    .
  2. ^ Martin, R. Aidan (February 2010). "Batoids: Sawfishes, Guitarfishes, Electric Rays, Skates, and Sting Rays". Elasmo research. ReefQuest Centre for Shark Research.
  3. S2CID 28305317
    .
  4. ^ Wilga, C.A.D. (2008). "Evolutionary divergence in the feeding mechanism of fishes". Acta Geologica Polonica. 58: 113–20.
  5. ^ "Reproduction overall". Risk Section, Bedford Institute of Oceanography & Marine Fish Species. Canadian Shark Research Lab. Skates and rays of Atlantic Canada. Northwest Atlantic Fisheries Center. Archived from the original on 16 January 2015. Retrieved 27 May 2012.
  6. ^
    S2CID 90834034. Archived from the original
    on 2019-02-23. Retrieved 2018-12-09.
  7. doi:10.1007/s12542-019-00451-4
    .
  8. ^ "Chondrichthyes: Fossil Record". University of California Museum of Paleontology. U.C. Berkeley.
  9. PMID 12565032
    .
  10. ^ Kriwet, Jürgen. "The systematic position of the Cretaceous sclerorhynchid sawfishes (Elasmobranchii, Pristiorajea)" (PDF). Archived from the original (PDF) on 2016-04-16. Retrieved 2016-04-04.
  11. ^ McEachran, J.D.; Aschliman, N. (2004). "Phylogeny of batoidea". In Carrier, J.C.; Musick, J.A.; Heithaus, M.R. (eds.). Biology of sharks and their relatives. Boca Raton, Florida: CRC Press. pp. 79–114.
  12. ^
    ISBN 978-0-471-25031-9
    .
  13. ^
    ISBN 978-0-387-23192-1
    .
  14. ^
    doi:10.1111/j.1096-3642.2012.00872.x
    .
  15. S2CID 231723355
    .
  16. ^ Briggs, Helen (28 January 2021). "Extinction: 'Time is running out' to save sharks and rays". BBC News. Retrieved 29 January 2021.
  17. ^ Richardson, Holly (27 January 2021). "Shark, ray populations have declined by 'alarming' 70 per cent since 1970s, study finds". ABC News. Australian Broadcasting Corporation. Retrieved 29 January 2021.
  18. ^ Guide of Mediterranean Skates and Rays. Oct. 2022. Mendez L., Bacquet A. and F. Briand.[1]

Bibliography

  • McEachran, J.D.; Dunn, K.A.; Miyake, T. (1996). "Interrelationships of the batoid fishes (Chondrichthyes: Batoidea)". Interrelationships of Fishes. Academic Press.
  • ISBN 9780471756446
    .

External links

  • "Shark references". – database of bibliography of living/fossil sharks and rays (see Chondrichtyes: Selachii) with more than 15 000 listed papers and many download links.
  • "Rays Fact Sheet". Rays fact sheet (PDF). Fisheries (Report). Recreational fishing. Perth, Australia: Government of Western Australia. Archived from the original (PDF) on 13 May 2013.


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