Question: What is the difference between a catshark and a dogfish?

Lesser-Spotted Catshark answered on 17 Nov 2017:

Catsharks are a group of Carchariniform sharks in the family Scyliorhinidae. There are about 80 known species of which the lesser-spotted catshark (Scyliorhinus canicula) is just one. Dogfishes are a different group of Squaliform sharks from the family Squalidae and a common one around the UK is the spiny dogfish (Squalus acanthias). Some people will confuse the two groups and often the lesser-spotted catshark and other small sharks are lumped in together under the term ‘dogfish’. This is just an error, albeit a widespread one. It is the aquatic equivalent of calling every small bird you see a robin just because it is a smallish bird.