The spiny dogfish shark (Squalus acanthias) is the most common shark and travels in schools. They are called dogfish because they travel and hunt in packs. Estimates of the dogfish's life span range from 30-100 years. It has the longest gestation period of any vertebrate, 18-24 months.

The Spiny Dogfish Shark (Squalus acanthias) -- This small, slender shark has a flattened head and a snout that tapers to a blunt tip. It averages 2 1/2 to 3 feet in length with the largest growing to 4 feet or more. Its mouth is full of low, flat, grinding teeth like the smooth dogfish, but the spiny dogfish also possesses an extra set of small, very sharp teeth. Two features distinguish the ...