Myliobatiformes

Dasyatis kuhlii

The stingray -like are the most highly developed and most specialized order of skates ( Batoidea ). They inhabit mainly tropical, subtropical and temperate zones of all oceans. They include the famous manta ray (Manta ), although they are spineless, and the South American freshwater stingrays ( Potamotrygonidae ), the only family of cartilaginous fish ( Chondrichtyes ) that is found exclusively in fresh water.

Features

Head, torso, and the pectoral fins of stingray -like form a broad, diamond-shaped, oval or triangular body disc. In some forms, have given up life on the sea floor, the pectoral fins have evolved into broad wing-like locomotion organs with which they virtually " fly " through the water. The fins carrier ( radials ) of the pectoral fins are up to tip of the rostrum. The tail is penetrated whip-like and very slim. A tail and a single dorsal fin absent or small. Most species have on the tail top one or more long, sawed poisonous sting. The sting is a modified Placoidschuppe, coated with toxic tissue and is only used for defense. Electric organs missing forever. The skin is covered naked or with small placoid scales. The nostrils are close together. Compared with other rays the stingray -like have large brains. Stingray -like do not have ribs. The shoulder blade and the coalesced, located at the front part of the spinal column are connected via a ball joint. With the exception of the six- gill stingray ( Hexatrygon bickelli ) have all stingray -like five gill slits on each side. They are ovoviviparous.

System

The stingray -like i.e.S. are counted according to Nelson ( 2006) eight families. Within the Myliobatoidei there are 24 genera and about 180 species.

• Stingray -like i.w.S. ( Myliobatiformes ) Subordination Platyrhinoidei Thorn back guitar sharks ( Platyrhinidae )

• Zanobatidae

• Superfamily Hexatrygonoidea Six gill stingray ( Hexatrygonidae )

• Deepwater stingrays ( Plesiobatidae )
• Round stingrays ( Urolophidae )

• American round stingrays ( Urotrygonidae )

• Stingray ( Dasyatidae )
• Freshwater stingrays ( Potamotrygonidae )
• Butterfly ray ( Gymnuridae )
• Eagle rays ( Myliobatidae )