A catshark with a wide range

The Mouse catshark (Galeus murinus) is a species of catshark belonging to the family Scyliorhinidae. It is common in the northeastern Atlantic Ocean from Iceland to Faroes. The Mouse catshark has a uniformly brown body and is characterized by large, rounded pelvic fins and crests of enlarged dermal denticles along both the dorsal and ventral caudal fin margins.


Family: Scyliorhinidae – Catsharks

Genus: Galeus 

Species: murinus


Phylum– Chordata

Class– Chondrichthyles


Common NameGround Sharks

Family– Scyliorhinidae

Common NameCatsharks




Average Size and Length: Adult males measure between 50-63 cm/1.6-2.1 feet. Females have been recorded at 53 cm/1.7 feet, more than likely more sample specimens need to be recorded.

Current Rare Mythical Sightings: Norwegian zoologist Robert Collett originally described the mouse catshark as Pristiurus murinus, in a 1904 issue of the scientific journal Forhandlinger i Videnskabs-selskabet i Christiania; its specific epithet means “relating to a mouse” in Latin. The type specimen is an immature female 22 cm/8.7 inches long, collected 150 km/93 miles northwest of the Hebrides at a depth of 1,100–1,300 m/3,608–4,265 feet. Later authors have recognized Pristiurus as a junior synonym of Galeus.

Teeth and Jaw: The mouth is blackish in color. The mouth is large and forms a wide arch, with well-developed furrows at the corners. The teeth have a narrow central cusp and multiple lateral cusplets on either side.

Head: The snout is long and blunt. The nostrils are divided by triangular flaps of skin in front. The eyes are horizontally oval and equipped with nictitating membranes. A thin ridge is present beneath each eye, and a tiny spiracle behind.

Denticles: There is a distinct crest of enlarged dermal denticles along the upper margin of the tail, and along the ventral midline of the caudal peduncle. The dermal denticles are small and overlapping. Each one has an arrowhead-shaped crown with a horizontal ridge and three marginal teeth.

Tail: The precaudal tail is cylindrical, not flattened. The tail is elongated. The caudal fin is low, with a small lower lobe and a ventral notch near the tip of the upper lobe.

Demographic, Distribution, Habitat, Environment and Range: The Mouse catshark can be found in the northeast Atlantic Ocean on the west coast of Iceland to Faroe Channel (66°N – 61°N, 28°W – 5°W). They also may be found in Hebrides, Scotland, and Ireland, to as far south as France and even possibly Western Sahara (but this is not confirmed). They are found on the continental slope on or near the bottom between 1,247-4,101 feet. They are considered bathydemersal.

Diet: More than likely, it preys mainly on benthic crustaceans, bony fishes, and cephalopods close to the sea floor. This would consist primarily of shrimp such as Pasiphaea multidentata and Sergestes robustus, other crustaceans such as Dorhynchus thomsoni, bony fishes such as Micromesistius poutassou, and cephalopods.

Aesthetic Identification: The Mouse catshark has a firm body, that is uniform brown dorsally, and slightly paler ventrally. There are five pairs of gill slits. The first dorsal fin has a rounded tip and is positioned over the aft portion of the pelvic fins. The second dorsal fin is similar in size and shape as the first, and is positioned over the aft portion of the anal fin. The pectoral fins are large and broad. The pelvic fins are distinctive, being large and wide with an evenly rounded margin. In adult males, the inner margins of the pelvic fins are fused together to form an apron partially covering the claspers. The anal fin is large and angular. Its base measures roughly 12–13% of the total length, much longer than the distance between the dorsal fins. The pelvic, anal, and caudal fins are all very close to each other.

Biology and Reproduction: Unknown, but more than likely oviparous, and some reports are coming in about the egg cases, which seem to be “furry” due to tiny fibers covering it. The egg cases are supposedly golden yellow and vase-shaped, measuring 5.4–5.6 cm/2.1–2.2 inches long and 1.4–1.7 cm/0.55–0.67 inches across. It is squared off at the top and the bottom with a short projection.

The young are estimated to hatch at a length of approximately 8–9 cm/3.1–3.5 inches.

A 2005 phylogenetic analysis by Samuel Iglésias and colleagues, based on mitochondrial and nuclear DNA, found that G. murinus forms a clade with G. melastomus, apart from the clade of G. eastmani, G. sauteri, and G. gracilis.

Behavioral Traits, Sensing and Intelligence: Unknown.

Mouse Catshark Future and Conservation: They are considered of least concern. They are caught incidentally by commercial trawl fisheries, but does not appear to be threatened by fishing activities.

Mouse Catshark Recorded Attacks on Humans: Not a threat to humans.