Science, Tech, Math › Animals & Nature Ray-Finned Fishes (Class Actinopterygii) This group encompasses over 20,000 species of fish Share Flipboard Email Print Klaas Lingbeek- van Kranen/E+/Getty Images Animals & Nature Marine Life Marine Life Profiles Marine Habitat Profiles Sharks Key Terms Amphibians Birds Habitat Profiles Mammals Reptiles Wildlife Conservation Insects Forestry Dinosaurs Evolution View More By Jennifer Kennedy Marine Science Expert M.S., Resource Administration and Management, University of New Hampshire B.S., Natural Resources, Cornell University Jennifer Kennedy, M.S., is an environmental educator specializing in marine life. She serves as the executive director of the Blue Ocean Society for Marine Conservation. our editorial process Jennifer Kennedy Updated February 16, 2018 The group of ray-finned fishes (Class Actinopterygii) encompasses over 20,000 species of fish that have 'rays,' or spines, in their fins. This separates them from the lobe-finned fishes (Class Sarcopterygii, e.g., the lungfish and coelacanth), which have fleshy fins. Ray-finned fishes make up about half of all known vertebrate species. This group of fish is very diverse, so species come in a wide variety of shapes, sizes, and colors. The ray-finned fishes include some of the most well-known fish, including tuna, cod, lionfish, and even seahorses. Classification Kingdom: AnimaliaPhylum: ChordataClass: Actinopterygii Feeding Ray-finned fishes have a wide variety of feeding strategies. One interesting technique is that of the anglerfish, which entice their prey toward them using a movable (sometimes light-emitting) spine that is above the fish's eyes. Some fish, such as the bluefin tuna, are excellent predators, speedily capturing their prey as they swim through the water. Habitat and Distribution Ray-finned fishes live in a wide variety of habitats, including the deep sea, tropical reefs, polar regions, lakes, rivers, ponds and desert springs. Reproduction Ray-finned fishes may lay eggs or bear live young, depending on the species. African cichlids actually keep their eggs and protect the young in their mouth. Some, like seahorses, have elaborate courtship rituals. Conservation and Human Uses Ray-finned fishes have long been sought for human consumption, with some species considered overfished. In addition to commercial fishing, many species are recreationally fished. They are also used in aquariums. Threats to ray-finned fishes include overexploitation, habitat destruction, and pollution.