Skates and rays are essentially flattened sharks, inhabiting deep and shallow waters across the world. As a rule, skates lay eggs (the famous ‘mermaid’s purses’) while rays give birth to live young, but unless you are lucky enough to witness either event, you will need to look at anatomy to tell the difference between them.
How to tell the difference between skates and rays
The first indicator is the tail. Pelagic rays often have slender, whip-like tails, and those of some species are adorned with a venomous spine. Rays that live on the seabed may sport shorter, stockier tails, but in that case the presence of a spine is generally the giveaway.
Skates often have longer, pointier snouts; more diamond or kite-shaped bodies; those stockier tails and no venomous spine. They usually have a prominent dorsal fin (which is smaller or absent in rays) and thorny barbs on their backs that they use for defence.
Names can sometimes cause confusion, though. Many skates in the UK are referred to as rays – including the thornback and undulate rays.
Main image: Spotted eagle ray (Aetobatus narinari) © Vincent Pommeyrol/ Getty Images