Actinopterygii

Definition

Actinopterygii are a class of ray-finned fishes, characterized by their fin structure. Their fins are supported by bony or horny spines known as rays, rather than fleshy, lobed fins like those of lobe-finned fish.

5 Must Know Facts For Your Next Test

1. Actinopterygii is the largest class of vertebrates, with over 30,000 species.
2. They exhibit a wide range of sizes from tiny minnows to large marlins and tunas.
3. Most actinopterygians have swim bladders that help them control buoyancy.
4. They possess gills covered by an operculum which aids in respiration.
5. Ray-finned fishes have diverse reproductive strategies including oviparity (egg-laying) and viviparity (live-bearing).

Review Questions

• What key structural feature distinguishes Actinopterygii from other fish classes?
• How do swim bladders benefit ray-finned fishes?
• Name two reproductive strategies observed in Actinopterygii.

Related terms

Chordata: Phylum that includes all vertebrates characterized by having a notochord at some stage in their development

Swim Bladder: An internal gas-filled organ that helps fish control their buoyancy

Operculum: A bony plate that covers and protects the gills in fish