Dec 21, 2025 · Fish - Classification, Jawless, Cartilaginous & Bony Fishes: Fishes are typically divided into three groups: superclass Agnatha (jawless fishes), class Chondrichthyes …

Dec 21, 2025 · Bottom-living fishes are of many kinds and have undergone many types of modification of their body shape and swimming habits. Rays, which evolved from strong …

pleuronectiform, (order Pleuronectiformes), any one of about 680 species of bony fishes characterized by oval-shaped, flattened bodies as in the flounder, halibut, and turbot. The …

Dec 21, 2025 · The evolution of several other, better-adapted fish groups soon followed the appearance of the placoderms, and this apparently led to their early extinction. Their greatest …

Fish scales are formed of bone from the deeper, or dermal, skin layer. The elasmobranchs (e.g., sharks) have placoid scales, which are bony, spiny projections with an enamel-like covering.

The most abundant group of fish is the Osteichthyes, or bony fish. Examples of bony fish range from the tiny seahorse to the 1,000-pound (450-kilogram) blue marlin and from the flattened …

Thickset fish with large heads and mouths, small eyes, and bumpy skins covered with wartlike lumps and, sometimes, fleshy flaps, they rest on the bottom, unmoving, blending almost …

Locomotion - Anguilliform, Wave, Jet: When an elongated fish such as an eel swims, its entire body, which is flexible throughout its complete length, moves in a series of sinuous waves …

Dec 26, 2025 · Stingrays are disk-shaped and have flexible, tapering tails armed, in most species, with one or more saw-edged, venomous spines. They inhabit warm temperate and tropical …

Dec 21, 2025 · Mouth shape and tooth structure vary greatly in fishes, depending on the kind of food normally eaten. Most fishes are predacious, feeding on small invertebrates or other fishes …