Fauna
Fish

Spiny Dogfish

Squalus acanthias

Also known as Spurdog, Mud Shark, Piked Dogfish

Spiny dogfish travel coastal temperate waters worldwide in dense single-sex schools, migrating seasonally in search of schooling prey. Females experience one of the longest gestation periods of any vertebrate, lasting up to two full years before giving birth to live pups. Distinct sharp spines located directly in front of each dorsal fin offer protection against larger marine predators.

SchoolingVenomous SpinesMigratory
Spiny Dogfish reference1 / 3
(c) Ecomare/Salko de Wolf, some rights reserved (CC BY-SA) · cc-by-sa
—observations
—countries
—peak records
VulnerableConservation statusIUCN Red List categoriesLCNTVUENCREWEXVulnerableRed List categories, explained →
Key facts
Diet & preyAtlantic Herring, Squid, Crabs
Predators
  • Great White Shark
  • Orca
  • Grey Seal
ThreatsCommercial overfishing, bycatch, targeted squalene trade
HabitatsBenthic and pelagic zones of temperate shelf waters
Life span35–75 years
Classification
  1. FamilySqualidae
  2. SpeciesSqualus acanthias
Range & activity
Range data is not available yet.
Safe observation
Interaction riskVery high
  1. Low
  2. Moderate
  3. High
  4. Very high
Why interaction risk is very high
Sharp dorsal spines secrete a mild toxin; avoid direct contact if landed or handled.
Why it is dangerous
Dorsal fin spines possess mild venom glands that inflict painful wounds and cause swelling upon skin puncture.
How to recognize a risky encounter
Look for two dorsal fins, each fronted by a prominent sharp spine, alongside a sleek grey body with scattered white spots.
What to do
Keep a safe distance when swimming, and use padded grips or heavy gloves if unhooking an accidental catch.
What to notice
Recognized by its slender grey body, white belly spots, lack of an anal fin, and twin dorsal spines.
Support conservation
Release accidental catches quickly using proper dehooking tools to minimize post-release stress.
Responsible observation
  • Boating Etiquette: Maintain safe distance around shallow reefs or coastal kelp forests where dogfish congregate.
  • Hook Release: Use long-nosed pliers to remove hooks quickly, avoiding the defensive arching of their sharp spines.
  • Responsible Observation: View these sharks while diving without attempting to touch or corner them.
Related species
Help improve the field guideSomething wrong?

Report a name, category, or profile issue for review.

Checking your Fauna account…