General: Skates

Various stages in development of Arctic skate fry. © Arve Lynghammar

Rays and skates are closely related to sharks... except they are flattened. 

The fossil record of rays/skates goes all the way to the Lower Jurassic (about 150 million years ago). Due to these animals having skeletons made out of cartilage, they leave little fossil record except teeth. 

​Skates belong to the family Rajidae, in the superorderBatoidea. There are more than 200 different species that are divided into 27 genera. The two subfamilies are Rajinae (hardnose skates) and Arhynchobatinae (softnose skates). "So, how can you tell the difference between a ray and skate?" Well, there are a few ways.

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First, rays are generally larger than skates. Skates usually have a prominent dorsal fin, which is small, if not absent, in rays. Rays are usually kite shaped or rounded, with whip-like tails that have spine(s) that have the ability to deliver a painful, and venomous, sting. Meanwhile, skates have a fleshy tail that lacks spines, therefore they protect themselves with large thorns on their backs and tails. 

Skates also have small teeth, and rays have plate-like teeth (for crushing prey). Their major difference lies internally, though: their reproductive strategies. Rays are viviparous (bear live young) while skates are oviparous (lay leathery eggs, similar to shark egg capsules).  

© africanaquatics.co.za

​The common skate (Dipturus batis) is the largest skate in the world, reaching up to 2.5 m (8.2 ft) in length; they can get to be up to 50 years old! The smallest skate is the starry skate (Raja stellata), only obtaining a total length of 0.76 m (about 2.5 ft).

"So are they harmful to humans?" Skates, which lack stinging spines, are completely harmless to humans! You might get a bit scratched up from the thorns due to improper handling, but nothing a band-aid can't fix in a quick minute.
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differences between skates vs rays

Characteristic
Reproduction

Dorsal fin(s)

Pelvic fins

Tail
​
Protection



​Teeth

​Size

Skates
Oviparous

Distinct

Fins have 2 lobes

Fleshy, lack spine
​
Have "thorny projections on their backs and tails for protection from predators" 
​
Small
​
Smaller than rays

Rays
Viviparous

Missing or vestigial

Fins have 1 lobe 

Whip-like with stinging spine(s)
​
Rely on their stinging spines or barbs for protection 
​

Plate-like teeth
​
Larger than skates

glossary ​

• Dorsal fin: Fin located on the back.
• IUCN: International Union for Conservation of Nature.
• Generas: Plural form of genus.
• Genus: A group of organisms ranking above a species and below a family.
• Oviparity/oviparous: Where adult Chondrichthyans lay eggcases (also known as ‘mermaid’s purses) and the baby develops inside the egg before hatching.
• Pelvic fins: Fins located behind the gills on either side.
• Pup: Give birth to baby sharks (pups).
• Pups: Baby sharks.
• Viviparous: Eggs hatch inside the female's body and the babies are fed by a placenta which transfers nourishment from the mother to the babies (via an umbilical cord which is connected to the baby shark between the pectoral fins).​

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