鳐总目总目

分类

• 鳐目 Rajiformes
• 鳐科 Rajidae
• 无鳍鳐科 Anacanthobatidae
• 单鳍鳐科 Arhynchobatidae
• 吞鳐科 Gurgesiellidae
• 电鳐目 Torpediniformes
• 澳洲睡电鳐科 Hypnidae
• 双鳍电鳐科 Narcinidae
• 单鳍电鳐科 Narkidae
• 电鳐科 Torpedinidae

黄点𫚙科 Platyrhinidae：或称团扇鳐科。

• 犁头鳐目 Rhinopristiformes
• 蓝吻犁头鳐科 Glaucostegidae
• 锯鳐科 Pristidae
• 圆犁头鳐科 Rhinidae
• 犁头鳐科 Rhinobatidae
• 南犁头鳐科 Trygonorrhinidae
• 燕𫚉目 Myliobatiformes
• 梳板鳐亚目 Zanobatoidei
• 梳板鳐科 Zanobatidae
• 燕𫚉亚目 Myliobatoidei
• 六鳃𫚉总科 Hexatrygonoidea
• 六鳃𫚉科 Hexatrygonidae
• 扁𫚉总科 Urolophoidea
• 近𫚉科 Plesiobatidae

扁𫚉科 Urolophidae：或称平𫚉科。

• 巨尾𫚉总科 Urotrygonoidea
• 巨尾𫚉科 Urotrygonidae
• 𫚉总科 Dasyatoidea
• 𫚉科 Dasyatidae
• 江𫚉科 Potamotrygonidae

燕𫚉科 Gymnuridae：或称鸢𫚉科。

鲼科 Myliobatidae

Batomorphi is a division of cartilaginous fishes, commonly known as rays; this taxon is sometimes considered as the superorder Batoidea, but the 5th edition of Fishes of the World classifies it as the division Batomorphi. Batomorphi, along with the shark division Selachii, both compose the subclass Elasmobranchii. Rays are the most speciose of cartilaginous fishes groups, with well over 600 species in 26 families. Rays are distinguished by their flattened bodies, enlarged pectoral fins that are fused to the head, and gill slits that are placed on their ventral surfaces.

Description

Anatomy

Like sharks, Batomorphs are cartilaginous fish (Chondrichthyes), meaning they have a boneless skeleton made of a tough, elastic cartilage. Most batomorphs are dorsoventrally flattened, with a mantle-like body, though the guitarfishes and sawfishes are somewhat less flattened, while most sharks have a spindle-shaped body. Many species of batomorph have developed their pectoral fins into broad flat appendages often referred to as the wings. The anal fin is absent. The eyes and spiracles are located on top of the head. Bottom-dwelling batomorphs breathe by taking water in through the spiracles, rather than through the mouth as most fish do, and passing it outward through the gills, whose openings or gill slits lie under the pectoral fins on the underside, whereas a shark's are on the sides of the head. Most batomorphs have five ventral gill slits, but the Hexatrygonidae have six.

Batomorphs have a ventrally located mouth and can considerably protrude their upper jaw (palatoquadrate cartilage) away from the cranium to capture prey. The jaws have euhyostylic type suspension, which relies completely on the hyomandibular cartilages for support. Most batomorphs 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 using dense gill rakers to capture them.

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).

Evolution

Batomorphs belong to the ancient lineage of cartilaginous fishes. Fossil denticles (tooth-like scales in the skin) resembling those of today's chondrichthyans date at least as far back as the Ordovician, with the oldest unambiguous fossils of cartilaginous fish dating from the middle Devonian. A clade within this diverse family, the 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. The clade is represented today by sharks, sawfish, rays and skates.

Classification

Molecular evidence refutes the hypothesis that skates and rays are derived sharks. The monophyly of the skates, the stingrays, and the electric rays has long been generally accepted. Along with Rhinopristiformes, these comprise the four traditionally accepted major batomorph lineages, as in Nelson's 2006 Fishes of the World. However, the exact phylogeny of the major batomorph lineages, internally and with respect to one another, has been subject to diverse treatments. The following cladogram is based on a comprehensive morphological assessment of batomorph phylogeny published in 2004:

However, a 2011 study significantly reevaluated the phylogeny of batomorphs, using nuclear and mitochondrial DNA from 37 taxa, representing almost all recognized families and all of the traditional four major lineages. This is a far more numerous and diverse set of sample taxa than in any previous study, producing findings reflected in the cladogram below.

Conservation

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. 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.