The Order Squaliformes comprises a group of cartilaginous fishes commonly known as dogfish sharks and their relatives. These sharks are generally small to medium-sized, with two dorsal fins—often equipped with spines—and no anal fin. Squaliformes are mostly deep-sea dwellers, exhibiting adaptations to cold, high-pressure environments, such as slow metabolism and bioluminescence in some species. They are primarily carnivorous, feeding on fish, squid, and crustaceans, and play an important role in maintaining the balance of deep-sea ecosystems. This order is widely distributed across oceans, from shallow coastal waters to the deep sea.