What are skates and how are they different from rays?

Recently, a subscriber wanted to learn more about skates. Great question since many of us think of ‘roller’ when we think ‘skate’. Skates are a species that often get overshadowed by rays, especially considering rays tend to be boldly colored while skates tend to be rather dreary and drab in coloration. Rays are also found closer to the coast and skates prefer deep water so we may be more familiar with running into (or focused on learning to avoid) rays. However, there are exceptions to those generalizations within the 100 species of skates and 240 species of rays found worldwide.

They’re both flat diamond-shaped fish with their mouths on the underside of their body. Both of their body types can be described as dorsoventral. Skates and rays are cartilaginous fish, like sharks and chimaera, which all make up the class Chondrichthyes (Con-drick-thees). Cartilage is the material that makes up our nose and ears and is more flexible than bone. Skates and rays  have modified fins, resembling wings, and often look as though they are flying through the ocean.

Here are six general guidelines for differentiating a skates and rays.

  • The pelvic fin of skates is divided into two lobes, while the pelvic fin of rays is a single lobe.
  • The tail on skates lacks a stinging spine. Rays have a distinct, saw-edged spine found midway along their body length. (When swimming in the habitat of stingrays it is important to remember to do the ‘stingray shuffle‘.)
  • Many species of skates have bucklers (thorn-like scales along the mid-line of their back and tail. Rays typically have no bucklers.
  • The tail of skates is rather thick and compact, while rays typically have a slender and long tail.
  • Male skates have enlarged scales near their eyes and wingtips, known as ‘malar’ and ‘alar’ spines.  Male rays do not have these scales.
  • Skates live in cold waters, while rays prefer warm seas and rivers.

For more information about skates and rays, check out the ReefQuest Centre for Shark Research.

Photo (c) www.animals.howstuffworks.com

Are stingrays related to sharks?

English: Various types shown. Taken at Mote Ma...

Image via Wikipedia

Stingrays and sharks are very closely related. They belong to a group of fishes called the elasmobranchs. All elasmobranchs have 1) skeletons made of cartilage (the flexible material that makes up the tip of our nose and ears) and 2) 5-7 gill slits. Elasmobrachs includes sharks, rays, and skates.

It’s not entirely incorrect to think of stingrays as flattened sharks. On the inside, they’re just about the same. There are some animals that blur the lines between the two. Angel sharks and wobbegongs are flat, but they’re not rays. Then there are sawfish (which are rays) and sawsharks (which are sharks). Sharkrays are just plain confused. As a general rule, if the gill slits are on the bottom, it’s a ray. If they’re on the side, it’s a shark.

Jim Wharton
Vice President, Education Division, Director, Center for School and Public Programs, Mote Marine Laboratory

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