Kõhrelistest

Kõhrelistest is an Estonian term that translates to "cartilaginous fishes" in English. This broad category encompasses a group of fish belonging to the class Chondrichthyes. Unlike bony fishes (Osteichthyes), cartilaginous fishes have skeletons made primarily of cartilage rather than bone. This characteristic is a defining feature of the group.

The class Chondrichthyes is further divided into two subclasses: Elasmobranchii and Holocephali. Elasmobranchii includes sharks, rays, and skates. These creatures are known for their streamlined bodies, multiple gill slits, and placoid scales, which are small, tooth-like structures that give their skin a rough texture. Sharks are typically predators, while rays and skates are often bottom-dwellers with flattened bodies adapted for their environment. Holocephali, also known as chimaeras or ghost sharks, represent a smaller and more ancient lineage. They possess a single gill opening covered by a flap of skin and have teeth fused into grinding plates.

Cartilaginous fishes inhabit oceans worldwide, from shallow coastal waters to the deep sea. They exhibit a wide range of sizes and ecological roles, from the massive whale shark to the small lantern shark. Their reproductive strategies vary, with some species laying eggs (oviparous) and others giving birth to live young (viviparous or ovoviviparous). The cartilaginous skeleton, while lighter than bone, still provides significant structural support and allows for diverse forms and adaptations within this ancient group of fishes.