Rays Fishes Views
The ray-finned fishes are so called because they possess lepidotrichia or fin rays , their fins being webs of skin supported by bony or horny spines ( rays ), as opposed to the fleshy, lobed fins that characterize the class Sarcopterygii which also, however, possess lepidotrichia. These actinopterygian fin rays attach directly to the proximal or basal skeletal elements, the radials, which represent the link or connection between these fins and the internal skeleton (e.g., pelvic and pectoral girdles).
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.
The classification of batoids is currently undergoing revision; however, molecular evidence refutes the hypothesis that skates and rays are derived sharks.[5] Nelson's 2006 Fishes of the World recognizes four orders. The Mesozoic Sclerorhynchoidea are basal or incertae sedis; they show features of the Rajiformes but have snouts resembling those of sawfishes.
The reason is that sharks and rays are cartilaginous fishes. This means that instead of bone in their skeletons they have cartilagek—lighter and more elastic substance that has not fossilized like bone. The gristle found in meat is cartilage. (Another type of cartilaginous fish is the chimera, or ghost shark, which belongs in a sub-class all its own.)
Rays Fishes Images
