Undulate ray: A threatened skate with wavy brown markings found in the East Atlantic.

The undulate ray is a cartilaginous fish inhabiting sandy bottoms in the Mediterranean and East Atlantic. It faces endangerment from overfishing due to slow growth and late maturity, leading to strict catch bans in European waters.

Share on WhatsApp

Grows up to 100 cm in length
Lays leathery egg cases known as mermaid purses
Illegal to keep in EU waters since 2009
Reaches sexual maturity at eight or nine years
Prefers sandy and muddy seabeds

What it is

This skate has a flat, disc-shaped body that is triangular at the front and rounder at the rear. Its upper surface displays light brown to grey tones with dark wavy bands and small white spots. The underside is creamy-white. Spines protect the skin, arranged differently in males and females. Two dorsal fins sit near the end of a tail that matches the body in length.

Where it lives

Its distribution is patchy across the northeastern Atlantic, stretching from southern Ireland and England down to Senegal. It also lives in the western Mediterranean. While generally uncommon, it can be locally abundant near northwest Ireland, the eastern English Channel, and southern Portugal. It prefers sandy, muddy, or detrital seabeds between 50 and 200 metres deep.

How it lives

Little is known about its daily behaviour. It feeds on small fish, crustaceans, molluscs, and other bottom-dwelling creatures. Growth markers in vertebrae suggest a maximum lifespan of roughly two decades. As a benthic predator, it hunts along the sea floor, using its ventral mouth to capture prey hidden in the sediment.

Breeding and life cycle

Females lay eggs from March to September, producing around thirty per year. The eggs are encased in leathery black capsules with horny corners, often called mermaid purses. These cases measure up to 90 mm long. Sexual maturity arrives late, at eight years for males and nine for females. Reproductive activity peaks in winter.

A drawing made by EveryFish from what this page says. It is a diagram, not a picture of the real fish.

Fish and people

Commercial fisheries catch this ray using trawls, gillnets, and lines, either intentionally or as bycatch. It adapts reasonably well to captivity and appears in public aquariums. Due to stock declines, keeping undulate rays caught in EU waters has been illegal since 2009. Fishers must return them unharmed if possible to aid population recovery.

Status and threats

The species is classified as endangered. Overfishing poses a severe threat because the ray matures late and reproduces slowly. Populations have dropped sharply in the north Atlantic, with no recent records in the English Channel. Conservation measures now mandate the release of any accidentally caught individuals to prevent further depletion.

Questions people ask about Undulate ray

Is it legal to keep undulate rays?

No. Since 2009, it has been illegal to retain undulate rays caught in European Union waters. Fishers must return them to the sea unharmed if possible to help protect declining stocks.

What do undulate rays eat?

They feed on small fish, crustaceans, molluscs, and other macrobenthos found on the sea floor. Their ventral mouth allows them to hunt effectively in sandy and muddy habitats.

How big do they get?

An adult undulate ray typically weighs about 4.5 kg but can reach up to 10 kg. In terms of length, they can grow to a maximum of 100 cm, including their tail.

Good reading and sources

Where this page comes from

The facts on this page come from the Wikipedia article "Undulate ray", written by its contributors and used under the CC BY-SA 4.0 licence, and from its Wikidata record (CC0). EveryFish rewrote the text in its own words, with AI assistance, and compares every page with the article to make sure no passage is copied. It may be reused under the same CC BY-SA 4.0 licence with a link back.

It may contain mistakes, and figures change over time. Nothing here is investment or buying advice. If something is wrong, tell us. Last refreshed 2026-11-15.

Photo credits on this page

The small pictures above come from Wikimedia Commons under free licences. Some are cropped to fit.