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The Blackmouth catshark (Galeus melastomus) is a small, deep-water shark belonging to the family Pentanchidae (formerly Scyliorhinidae). It is characterized by its slender body, distinctive dark markings inside its mouth, and a series of dark saddles and spots on its dorsal surface. This species is a common inhabitant of continental shelves and slopes in the North Atlantic and Mediterranean Sea.
Physical Characteristics
- Body shape
- elongated
- Coloration
- Dorsal surface is typically greyish-brown to reddish-brown, marked with 8-10 distinct dark saddle-like blotches and numerous smaller dark spots. The ventral surface is paler, often whitish. The most distinctive feature is the black or dark grey lining of the mouth and gill slits.
- Scale type
- placoid
- Mouth position
- subterminal
- Distinctive features
- Black or dark grey lining of the mouth and gill slits, 8-10 dark saddle-like blotches on the dorsal surface, Numerous small dark spots scattered over the body, Rough skin due to dermal denticles, Two dorsal fins of similar size, located far back on the body, Caudal crest of enlarged dermal denticles along the dorsal margin of the caudal fin
- Dorsal fin
- Two relatively small dorsal fins, nearly equal in size. The first dorsal fin originates over or slightly behind the pelvic fin origins. The second dorsal fin originates over the anal fin.
- Tail fin
- Long, low caudal fin with a distinct notch near the tip of the upper lobe. The dorsal margin of the caudal fin has a prominent crest of enlarged, saw-like dermal denticles.
- Pectoral fin
- Moderately large and rounded.
- Distinctive fins
- Anal fin is long and low, originating beneath the first dorsal fin and extending to just before the caudal fin.
Identification Tips
Mouth and Gill Slits
The most reliable identifying feature is the black or dark grey coloration inside the mouth and gill slits, which is unique among catsharks in its range.
Body Coloration and Markings
Look for the distinctive pattern of 8-10 dark saddle-like blotches and numerous smaller dark spots on a greyish-brown to reddish-brown background.
Caudal Fin Crest
Examine the dorsal margin of the caudal fin for a prominent crest of enlarged, saw-like dermal denticles.
Body Shape
Its slender, elongated body is typical of many deep-water catsharks, but combined with the other features, it aids identification.
Habitat
- Water type
- saltwater
- Depth
- Typically found at depths of 150 to 1200 meters (490 to 3,940 feet), occasionally shallower (down to 50 meters) or deeper (up to 2000 meters).
- Environment
- Demersal, inhabiting continental shelves and slopes, often over muddy or sandy bottoms. Prefers cold, deep waters.
- Geographic range
- Eastern North Atlantic Ocean, from Iceland and Norway south to Senegal, including the Mediterranean Sea. Also found off the Azores and Madeira.
Aquarium Information
- Care level: expert
- Temperament: peaceful
- Diet: carnivore
- Minimum tank size: Not suitable for home aquaria due to size, depth requirements, and specialized care.
- Temperature: Typically 8-12°C (46-54°F)
- pH level: 7.8-8.4
- Hardness: High (marine salinity)
- Compatibility: Not compatible with typical aquarium setups. Requires specialized deep-water facilities.
- Special requirements: Requires very large, deep, cold-water aquaria with specialized filtration and lighting to simulate its natural deep-sea environment. Not a species for public or private aquariums without significant resources and expertise.
Wild Information
- Conservation status: least concern
- Seasonality: No specific seasonal patterns for commercial fishing; caught year-round as bycatch in deep-water fisheries.
- Market price: Low to moderate, often landed as bycatch.
- Commercial importance: low
- Taste: Mild, somewhat firm white flesh.
- Texture: Firm, flaky.
- Cooking methods: Fried, Grilled, Baked, Stewed
- Nutritional value: Good source of protein, low in fat. Mercury content can be a concern in larger, older individuals, though this species is relatively small.
Key Facts
Deep-Sea Dwellerinteresting
The Blackmouth catshark is a true deep-sea species, commonly found at depths where sunlight barely penetrates, relying on its keen senses to navigate and hunt in the dark.
Black Mouth Mysteryinteresting
The distinctive black lining of its mouth and gill slits, which gives it its common name, is thought to potentially aid in camouflage by making its mouth less visible when open in the dark depths, or perhaps plays a role in species recognition.
Egg-laying Sharkbehavior
Unlike many sharks that give live birth, the Blackmouth catshark is oviparous, laying distinctive, flask-shaped egg cases (mermaid's purses) on the seabed.
Dietary Generalistbehavior
This catshark is an opportunistic predator, feeding on a wide variety of small deep-sea invertebrates and fish, showcasing its adaptability in a resource-scarce environment.
Sawtail Featureinteresting
The crest of enlarged dermal denticles along the dorsal edge of its caudal fin gives it a 'sawtail' appearance, a feature shared with other members of the genus Galeus.
Safety Information
Safe- Safety level: safe
- Venomous: No
- Edibility: edible
- Handling notes: Blackmouth catsharks are not dangerous to humans. They are small and generally docile. Handle with care to avoid injury to the shark, especially if releasing. Their skin is rough due to placoid scales, so gloves are advisable to prevent abrasions.
Similar Species
Nursehound
Scyliorhinus stellaris
Lacks the black mouth lining. Has larger, more widely spaced spots and a more robust body. Found in shallower waters.
Small-spotted catshark
Scyliorhinus canicula
Lacks the black mouth lining. Has numerous small, closely packed dark spots and a more slender body. Found in shallower waters.
Iceland catshark
Galeus murinus
Also has a dark mouth lining, but its body coloration is more uniformly dark brown or grey, lacking the distinct saddles and spots of G. melastomus. Its range is generally further north and deeper.
Sawtail catshark
Galeus atlanticus
Similar in appearance but generally smaller and found in more restricted areas of the eastern Atlantic. Differentiation often requires careful examination of denticle patterns and fin proportions.
Scientific Classification
- Kingdom
- Animalia
- Phylum
- Chordata
- Class
- Chondrichthyes
- Order
- Carcharhiniformes
- Family
- Pentanchidae
- Genus
- Galeus
- Species
- melastomus
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