Thorny Skate | Oceana Canada

Canadian Marine Life Encyclopedia

Thorny Skate

Amblyraja radiata

Also known as

Thorny back, thornback, maiden ray, starry ray, starry skate

Distribution

North Atlantic; Northwest Atlantic from Greenland and Hudson Bay South Carolina

Ecosystem/Habitat

Soft bottoms

Feeding Habits

Active predator

Conservation Status

Special concern/data deficient

Taxonomy

Order Rajiformes (skates & relatives); Family Rajidae (skates)

Share

Facebook Twitter Pinterest Google+

Skates may look similar to flatfish, but they are actually much more closely related to sharks. Like sharks, a skate’s skeleton is made up of cartilage, which is softer and more flexible than bone. Skates commonly have small spines or modified scales on their bodies, but the thorny skate is aptly named because it is practically covered in these tiny thorny looking spines. They have a row of 10 to 20 large, conspicuous spines that run along their midline down their back and reaching their tail. They also have one large spine in front of and one behind each eye, large spines on each shoulder, and numerous smaller spines on their snout, pectoral fins and tail.

Thorny skates, like many other sharks, skates and rays, are slow-growing, late to mature and long-lived. It is believed that thorny skates can live to be at least 28 years old, however 16 to 20 years old is more common. They reach maturity at around 11 years and are able to reproduce year-round. Females lay approximately 40 to 56 egg cases per year, which are also called “mermaid’s purses.” These egg cases are rectangular capsules with tendrils at each corner to help secure them to seaweed or rocks. Each containing a single skate embryo, or baby skate, which will feed off of the yolk sac inside the egg capsule. When the baby skate reaches about 10 to 12 centimetres long it is fully formed and will emerge from the capsule. At this stage, the young skate mainly feeds on amphipods, which are extremely small, shrimp-like crustaceans. As they grow, their diet shifts more toward other bottom-dwelling organisms including polychaete worms, decapods (such as crabs, lobster, shrimp) and fish.