Fishes

There are over 34,000 recognized species of fish, making them the most diverse group of vertebrates. These species are classified into various types based on different criteria, including their anatomy, behavior, habitat, and other characteristics. Broadly, fish can be categorized into three main groups:

1. Ag­nath­ans (Jaw­less Fish): Fish without jaws, such as lampreys and hagfish.

2. Chon­dri­chthy­ans (Car­ti­lagi­nous Fish): Fish with skeletons made of cartilage rather than bone. This group includes sharks, rays, and skates.

3. Oste­ich­thy­ans (Bony Fish): Fish with skeletons made of bone. This group is further divided into two subgroups:

   - Sarcopterygii: Includes lobe-finned fish like coelacanths and lungfish.

   - Actinopterygii: Includes ray-finned fish, which constitute the majority of fish species. This subgroup is further divided into various orders and families.

Within these broad categories, there are numerous families, genera, and species, each with its own unique characteristics. The diversity of fish species is immense, with a wide range of sizes, shapes, colors, and behaviors, adapted to various aquatic environments around the world.