Taxon Description (Wikipedia)
The
Actinopterygii constitute the class or sub-class of the
ray-finned 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).
In terms of numbers, actinopterygians are the dominant class of marine environments from the deep sea to the highest mountain streams. Extant species can range in size from
Paedocypris, at...
full article at Wikipedia
