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Batoidea
Fossil range: Triassic–Recent
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Southern stingray (Dasyatis americana)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Superorder: Batoidea
Orders

Rajiformes - common rays and skates
Pristiformes - sawfishes
Torpediniformes - electric rays

Batoidea is a superorder of cartilaginous fish containing more than 500 described species in thirteen families. They are commonly known as rays, but that term is also used specifically for batoids in the order Rajiformes, the "true rays". Batoids include stingrays, skates, electric rays, guitarfishes and sawfishes.

Contents

Anatomy

Batoids are flat-bodied, and, like sharks, are a species of cartilaginous marine fish, meaning they have a boneless skeleton made of a tough, elastic substance. Most batoids have five ventral slot-like body openings called gill slits that lead from the gills, but the Hexatrygonidae have six.[2] Batoid gill slits lie under the pectoral fins on the underside, whereas a shark's are on the sides of the head. Most batoids have a flat, disk-like body, with the exception of the guitarfishes and sawfishes, while most sharks have a streamlined body. Many species of batoid have developed their pectoral fins into broad flat wing-like appendages. The anal fin is absent.

The eyes and spiracles are located on top of the head.

Habitat

Most species live on the sea floor, in a variety of geographical regions - many in coastal waters, few live in deep waters to at least 3,000 metres (9,800 ft), most batoids have a somewhat cosmopolitan distribution, in tropical and subtropical marine environments, temperate or cold-water species. Only a few species, like manta rays, live in the open sea, and only a few live in freshwater. Some batoids can live in brackish bays and estuaries. Bottom-dwelling batoids breathe by taking water in through the spiracles, rather than through the mouth as most fishes do, and passing it outward through the gills.

Feeding

Most batoids have developed heavy, rounded teeth for crushing the shells of bottom-dwelling species such as snails, clams, oysters, crustaceans, and some fish, depending on the species. Manta rays feed on plankton.

Classification



Selachimorpha


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Torpediniformes



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Pristiformes



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Rajiformes


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Myliobatiformes






Phylogenetic tree of Batoidea, from McEachran and Aschliman (2004)

The classification of batoids is currently undergoing revision. This article follows FishBase in dividing batoids into three orders. Some taxonomists argue in favour of placing all batoids in a single order, Rajiformes; others propose a division into five or six orders. The additional orders in these systems are Myliobatiformes, containing the eagle rays and their relatives; Rhinobatiformes, containing the guitarfishes (which may be further split into Rhynchobatiformes, containing the shovelnosed guitarfishes, and Rhiniformes, the sharkfin guitarfishes). The Mesozoic Sclerorhynchoidea are basal or incertae sedis; they show features of the Rajiformes but have shouts resembling those of sawfishes.

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Order Rajiformes (true rays)

Order Pristiformes (sawfishes)

Sawfishes are shark-like in form, having tails used for swimming and smaller 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 imbedded animals. Sawfishes can enter freshwater rivers and lakes. Some species reach a total length of 6 metres (20 ft).

Order Torpediniformes (electric rays)

Electric rays have organs in their wings that generate electric current. They are used to immobilize prey and for defense. The current is strong enough to stun humans, and the ancient Greeks and Romans used these fish to treat ailments such as headaches.[3]

References

  1. ^ Stevens, J. & Last, P.R. (1998). Paxton, J.R. & Eschmeyer, W.N.. ed. Encyclopedia of Fishes. San Diego: Academic Press. p. 60. ISBN 0-12-547665-5.  
  2. ^ Elasmo-research.org
  3. ^ Bullock, Theodore Holmes, Hopkins, Carl D., Popper, Arthur N., and Fay, Richard R. (2005). Electroreception. Springer. pp. 5–7. ISBN 0387231927.  

Wiktionary

Up to date as of January 15, 2010

Definition from Wiktionary, a free dictionary

Contents

Translingual

Etymology

Proper noun

Wikipedia-logo.png
Wikipedia has an article on:

Wikipedia

Batoidea

  1. a taxonomic superorder, within subclass Elasmobranchii - the rays
Wikispecies-logo.svg
Wikispecies has information on:

Wikispecies

Synonyms

See also

  • Myliobatiformes
  • Pristiformes
  • Rajiformes
  • Torpediniformes

Wikispecies

Up to date as of January 23, 2010
(Redirected to Rajomorphii article)

From Wikispecies

Taxonavigation

Main Page
Cladus: Eukaryota
Supergroup: Unikonta
Cladus: Opisthokonta
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Classis: Chondrichthyes
Subclassis: Elasmobranchii
Superordo: Rajomorphii
Ordines: Myliobatiformes - Pristiformes - Rajiformes - Torpediniformes

Vernacular names

Česky: Rejnoci
Deutsch: Rochen
Ελληνικά: Ραγιόμορφοι
English: rays
Français: Raie
Nederlands: Roggen
日本語: エイ上目
Polski: Rajokształtne
Русский: Скаты
Wikimedia Commons For more multimedia, look at Rajiformes on Wikimedia Commons.

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