Hexanchidae is a family of large, deep-water sharks that belong to the order Hexanchiformes. This family includes several species, with the most notable ones being the sixgill sharks. Hexanchidae is derived from the Greek word "hexa," meaning "six," and "anchi," meaning "hook," suggesting the presence of six pairs of gill slits, which is a distinct characteristic of this family. These sharks are commonly known as cow sharks due to their elongated body shape and slow, docile nature.
Hexanchidae are typically found in deep-sea environments, ranging from coastal waters to the abyssal zones of both temperate and tropical regions. They possess a unique feature of having an extra, rudimentary dorsal fin called a lumbar fin, located at the base of their tails, which sets them apart from other shark families. Additionally, they have a single dorsal fin, large pectoral fins, and a long, thick tail.
These sharks are considered voracious predators, feeding on a variety of prey including fish, squid, and other sharks. With their strong jaws and sharp teeth, they are well-equipped to crush and tear through their prey. Hexanchidae exhibit a live-bearing reproductive strategy, where the embryos develop within the mother's body until birth.
Due to their adaptation to deep-sea habitats, Hexanchidae are rarely encountered by humans, and as a result, there is limited information about their behavior and ecology. However, their unique anatomical features and evolutionary history make them a fascinating group of sharks for scientific study and research.
