Sealife guideThe thornback rayRaja clavata

Last updated on 07/06/2025 at 10:44 PM

Taxonomy

Common name: Thornback ray, roker
French name: Raie bouclée
Spanish name: Raya de clavos,raya común
Scientific name: Raja clavata (Linnaeus, 1758)
Family name: Rajidae
Order name: Rajiformes
Class name: Elasmobranchii

Description

The thornback skate is a medium-sized species, easily recognized by the presence of sharp, hook- or loop-shaped spines covering its dorsal surface, giving it a distinctive texture—especially along the midline of the back and on the tail, hence its name.

The thornback ray (Raja clavata) © Planctonvideo | Dreamstime.com

Its body is flattened and diamond-shaped, with broad pectoral fins fused to the head. The tail, clearly separated from the disc, is relatively slender and usually bears two small dorsal fins.

The thornback skate can reach up to 4 feet in length and typically weighs between 11 and 18 pounds. Its dorsal side is brown to grayish with light ocellated (eye-like) patterns, while its ventral side is white.

Geographic range

The thornback skate is widely distributed throughout the northeastern Atlantic ocean, ranging from Norway down to Morocco, including the Mediterranean sea and the Black sea.

Habitat

The thornback skate inhabits soft bottoms (sand, mud, gravel) at depths generally ranging from 33 to 984 feet, although it has been observed at depths of up to 3,280 feet in some areas.

Diet

The thornback skate is a carnivorous species that primarily feeds on small benthic fish, crustaceans such as crabs, shrimp and amphipods, as well as mollusks including cephalopods and bivalves.

It uses its ventral mouth to capture prey buried in the substrate by creating a strong suction.

Reproduction

The thornback skate is oviparous. Its breeding season mainly occurs in spring and summer but varies depending on latitude. Females lay their eggs enclosed in sturdy, rectangular-shaped capsules called mermaid’s purses, which measure approximately 2 to 3.5 inches in length.

Baby skates hatch fully formed after an incubation period of 4 to 6 months, depending on the surrounding seawater temperature.

Did you know ?

Due to its slow growth, late maturity and low reproductive rate, the thornback skate is particularly vulnerable to overfishing, as it is often caught as bycatch in bottom trawls and gillnets. Its population has noticeably declined in certain parts of its range, especially in the North sea.

The thornback ray is listed as many other marine species within The IUCN Red List of threatened species. The thornback ray appears in the IUCN Red List since 2016 within the category Near Threatened !

Within the same genus

Big skate
(Raja binoculata)

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(Physalia physalis)

Thornback ray
(Raja clavata)

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