Spiny dogfish

The spurdog is a small shark with a slender body and sharp spines in front of its dorsal fins. It roams cool coastal waters around the world, often in large groups. Unlike many sharks, it prefers chilly depths and can live for decades.

• Its dorsal fins have venomous spines for defense.
• Spurdogs sometimes gather in schools of hundreds.
• They mature slowly, taking up to 20 years to reproduce.