Squalus acanthias, commonly known as the spiny dogfish, is a small shark species found in temperate and subarctic oceans worldwide. It features a slender body, sharp dorsal spines, and a distinctive gray coloration with white spots. Typically inhabiting continental shelves, it is a social species known for forming large schools.

Squalus acanthias, commonly known as the spiny dogfish, is a species of shark found primarily in temperate and subarctic waters of the North Atlantic and North Pacific Oceans. In the North Atlantic, it ranges from Greenland to Argentina in the west and from Iceland and Norway to the Mediterranean Sea in the east. In the North Pacific, its distribution includes waters from the Bering Sea to Baja California in the eastern Pacific and from Russia to Japan in the western Pacific.

The spiny dogfish typically inhabits continental shelf and slope areas, favoring depths ranging from the surface to about 200 meters, but it can be found as deep as 900 meters. It prefers cool, temperate waters with temperatures ranging from 7°C to 15°C. This species is often found in coastal and offshore environments, including estuaries and bays, where it can tolerate a range of salinities.

Squalus acanthias is a highly migratory species known for forming large aggregations. It plays a significant role in the marine ecosystem as a predator of various fish and invertebrates, including herring, squid, and crustaceans. The spiny dogfish is known for its adaptability to different environmental conditions, which allows it to occupy a diverse range of marine habitats. Its ecological niche is characterized by its ability to exploit prey resources in both pelagic and demersal zones.