Black dogfish

© Irish Deepwater Survey/Irish Marine Institute

The black dogfish (Centroscyllium fabricii) is a small deepwater shark found on the outer continental shelf and slopes around 180-2,250 metres deep. Reaching to be least 90 cm in length, this schooling shark has a widespread distribution in the temperate Atlantic Ocean (there are a few tropical records but those have not been 100% confirmed). #Finfact: Parts of this shark can glow, too!

Now you may be wondering, "Woah, TFUI. Schooling? How?" According to the IUCN: "Exhibits size structure segregation by depth for both sexes off Iceland with the smallest immature specimens found at 1,000 and 1,500 m, and larger individuals at depths in between. The overall sex ratio off Iceland was 1.00:1.19 in favour of females. Males were more numerous in shallower waters but in depths >1,000 m, the sex ratio was significantly in favour of females (Jakobsdottir 2001)."

Speaking of females, it seems that in Canadian waters pregnant females migrate to the shallow (<400 m) part of the Laurentian Channel to pup (Kulka 2006). They are aplacental viviparous and their litters can have up to 40 pups (though that is not the average)! The young then move into deeper waters of the channel. As they grow they move onto the continental shelf where they feed on crustaceans, cephalopods, jellyfish and small fish. These dogfish are also scavengers. The IUCN has assessed these animals as Least Concern (LC).

WHAT DID YOU LEARN ABOUT THIS ANIMAL?

GLOSSARY

• Cephalopods: The most intelligent, mobile, and largest of all molluscs. These include: squid, octopuses, cuttlefish, the chambered nautilus, and their relatives.
• Continental shelf: Extends from a continent underwater, resulting in a shallow-water area.
• Continental slope: The steep slope from a continental shelf to the ocean floor; usually around 20 km (12.4 miles) wide and made up of mud and silt substrate. It is an ideal area for deep sea fishing.
• Crustaceans: Group of animals with a hard exoskeleton, jointed legs and segmented body.
• IUCN: International Union for Conservation of Nature.
• Pup: Give birth to baby sharks, skates, rays or chimaeras (pups).
• Pups: Baby sharks, skates, rays, or chimaeras.​
• Viviparous with yolk-sac: Also known as aplacental viviparous and previously known as ovoviviparous/ovoviviparity; it is the production of eggs that are fertilised and hatch inside the female shark but the embryos lack a placental connection to the oviduct or uterus and so do not feed off the mother.

SAY HELLO!

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