Actinopterygian
| Ray-finned fish Temporal range: Late Silurian–Recent |
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| Rose fish | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Superclass: | Osteichthyes |
| Class: |
Actinopterygii Klein, 1885 |
| Subclasses | |
Actinopterygii /ˌæktᵻnˌɒptəˈrɪdʒi.aɪ/, or the ray-finned fishes, constitute a class or subclass of the bony fishes.
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).
Numerically, actinopterygians are the dominant class of vertebrates, comprising nearly 99% of the over 30,000 species of fish. They are ubiquitous throughout freshwater and marine environments from the deep sea to the highest mountain streams. Extant species can range in size from Paedocypris, at 8 mm (0.3 in), to the massive ocean sunfish, at 2,300 kg (5,070 lb), and the long-bodied oarfish, at 11 m (36 ft).
Ray-finned fishes occur in many variant forms. The main features of a typical ray-finned fish are shown in the diagram at the left.
Tuna are streamlined for straight line speed with a deeply forked tail
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