The spiny dogfish shark is easily recognizable due to the two spikes on its back in front of each dorsal fin. Mildly poisonous, these spikes evolved as a defense mechanism against predators, including larger sharks and killer whales.
The spiny dogfish is a carnivorous creature that eats fish, squid, crustaceans, octopus and sometimes other sharks. Because of its relatively large size, its aggressive tendencies and venomous spikes, the spiny dogfish does not have many predators. According to A-Z Animals, the chief predators of spiny dogfish sharks are humans. Found in the Atlantic, Pacific and Indian Oceans, the spiny dogfish has a grey body with a pale underside, large eyes and a short snout. Its back is dotted with small white spots. The shark is easy to distinguish because unlike most shark species, spiny dogfish sharks don't have anal fins. This shark species doesn't lay eggs in the ocean. Instead, the shark hatches inside its mother, and the gestation period lasts up to two years. Litters can consist of anywhere between two to 15 pups. The spiny dogfish can travel for long distances. A spiny dogfish shark that was tagged and released in Washington reappeared more than 5,000 miles away in Japan.