Chordate Zoology - Textbook - Y. V. Tsaryk - 2013

Chapter 4. DIVISION GNATHOSTOMATA, or ECTOBRANCHIATA. SUPERCLASS PISCES

4.1. CLASS CARTILAGINOUS FISHES CHONDRICHTHYES

4.1.2. Distribution and Lifestyle of Cartilaginous Fishes

Cartilaginous Fishes are widely distributed in oceans and seas, and to a lesser extent, in fresh waters. They inhabit diverse biotopes, ranging from shallow waters to great depths (up to 2 000 m). Some of them are commercially important species. Cartilaginous fishes dangerous to humans are predominantly found in tropical waters.

Among cartilaginous fishes, there is A wide variety of life forms. A general biological principle holds true: the species with the largest individuals in the group are never predators. Most often, they are harmless planktivorous animals. As previously mentioned, the enormous whale shark, reaching 12-15 meters in length and weighing up to 14 t, is a typical filter feeder, subsisting on planktonic crustaceans, small fish, and squid.

The annual cycle of cartilaginous fishes may feature pronounced seasonal Migrations.

The populations of many species have significantly declined in recent years due to commercial fishing or even direct eradication, as is the case with sharks dangerous to humans.