White-spotted Dogfish

Overview

The White-spotted Dogfish (Squalus acanthias), also known as the spiny dogfish, is a slender, slow-swimming shark found in temperate and boreal waters worldwide. It is easily recognized by the two sharp spines located in front of its dorsal fins and its lack of an anal fin. This species is highly resilient and long-lived, with some individuals reaching ages of up to 75 to 100 years.

Distribution & habitat

This species has a nearly circumglobal distribution in temperate and boreal marine environments. They are highly migratory, often moving in response to seasonal changes in water temperature, and are typically found in coastal and offshore waters ranging from the surface to significant depths.

Appearance

The White-spotted Dogfish features a narrow, pointed head and a slender, streamlined body. Its dorsal and lateral surfaces are typically slate grey to bluish-grey, often marked with an irregular array of small white spots, while the underside is pale grey to white. The second dorsal fin is smaller than the first, and both are preceded by a prominent, sharp spine.

Biology & behavior

These sharks are gregarious and frequently form large schools, which are often segregated by size and sex. They are known for their slow growth and late maturity, with females maturing much later than males. The species is aplacental viviparous, meaning they give birth to live young that develop from eggs hatched inside the mother. They hold the record for the longest gestation period of any vertebrate, lasting between 18 and 24 months.