Rajidae
Rajidae is a family of cartilaginous fish commonly known as skates. This family belongs to the order Rajiformes, which also includes rays. Skates are found in all oceans around the world, inhabiting a variety of depths and habitats. They are characterized by their flattened bodies, pectoral fins that are fused to the head, and a generally triangular shape. Unlike their close relatives, rays, skates possess two dorsal fins located on the tail, instead of a single fin. These fins are typically located close to the tail tip. Skates are generally bottom-dwelling fish, feeding on a variety of invertebrates and small fish.
Characteristics
Skates have a number of distinctive characteristics that distinguish them from other ray-like fishes. These features include:
- Flattened bodies: Skates have a flattened, disc-shaped body, which allows them to lie flat on the seabed.
- Fused pectoral fins: The pectoral fins of skates are fused to the head, forming a continuous wing-like structure.
- Two dorsal fins: Unlike rays, which have a single dorsal fin, skates possess two dorsal fins located near the tip of their tails.
- Spiracles: Skates, like other rays, have spiracles, which are small openings behind their eyes. These openings allow them to breathe while lying on the seabed.
- Venomous spines: Many species of skates have venomous spines located on their tails. These spines can inflict painful wounds if the skate is disturbed or threatened.
Environment
Skates are found in all oceans of the world, inhabiting a variety of depths and habitats. They are generally found on the seabed, from shallow coastal waters to the deep sea. Some species are also found in estuaries and bays. Skates are adapted to living on the bottom, with their flattened bodies allowing them to lie flat and their spiracles allowing them to breathe while buried in the sand.
Diet
Skates are carnivorous fish, feeding on a variety of invertebrates and small fish. Their diet includes crustaceans, mollusks, worms, and small bony fish. They use their flattened bodies and strong jaws to crush their prey, and their sharp teeth to tear flesh.
Reproduction
Skates reproduce by laying eggs. The eggs are enclosed in tough, leathery cases, known as mermaid's purses. The eggs are often found attached to seaweed or rocks on the seabed. The embryos develop inside the eggs, feeding on yolk until they are ready to hatch.