The ray-finned fishes get their name from the fact that they have lepidotrichia or `` fin rays '' . Their fins are webs of skin held by bony or horny spines ( `` rays '' ) . 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 .