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Atlantic Sawtail Catshark

Galeus atlanticus

iNaturalist Wikipedia

A mysterious resident of the deep, the Atlantic Sawtail Catshark is a master of the Mediterranean's darkest corners. With its distinctive saw-like tail and elegant markings, this rare species offers a fascinating glimpse into life on the continental slope.

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Quick Identification

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Size

A small, slender shark reaching up to 45 cm (18 inches) in length; typically weighs less than 1 kg (2.2 lbs).

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Colors

Light greyish-brown base color with 15–18 distinct dark brown 'saddles' or blotches along the back and tail; the interior of the mouth is notably dark.

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Key Features

Prominent crest of enlarged, saw-like scales (dermal denticles) along the upper edge of the tail
Slender, elongated body with two small dorsal fins located far back
Series of dark, saddle-shaped markings along the dorsal surface

When You’ll See Them

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Activity pattern Active day and night

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Peak hours 12 AM - 12 PM (Consistent deep-sea activity)

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Season Year-round

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Diet Primary diet consists of small deep-sea crustaceans (shrimp and krill), cephalopods like small squid, and various bony fishes found near the seafloor.

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Habitat Deepwater continental slopes, specifically on muddy or sandy substrates at depths of 400 to 600 metres.

Behavior

The Atlantic Sawtail Catshark is a shy, bottom-dwelling species that spends its life cruising the dark, cold waters of the continental slope. Unlike the high-speed sharks of the open ocean, this species is a slow, methodical swimmer that stays within a few meters of the seabed. It is relatively solitary, though it may congregate in areas where food is abundant or for breeding purposes.

As a deep-water specialist, its interactions with humans are virtually non-existent outside of scientific research and accidental bycatch by commercial trawlers. It poses no threat to humans due to its small size and deep-sea habitat. Its behavior is largely dictated by the sparse availability of prey in the deep, leading it to be an opportunistic scavenger and hunter that relies on its keen sense of smell and electroreception to find food in near-total darkness.

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Camera Tips

Capturing the Atlantic Sawtail Catshark requires specialized equipment, as this species lives far below the reach of standard backyard gear. For those using deep-sea AI-powered cameras or Baited Remote Underwater Video (BRUV) systems, placement is everything. You must secure your rig to a weighted frame capable of withstanding the pressures at 400–600 meters. Aim the camera horizontally across the seafloor, as this species is strictly benthic and will rarely swim more than a meter or two above the substrate.

Since there is no natural light at these depths, high-quality infrared or low-intensity LED lighting is essential. Using a 'red light' spectrum is often preferred by researchers as it is less likely to spook deep-sea organisms that cannot perceive red wavelengths. To draw the catshark into the camera's field of view, use a perforated bait canister filled with oily fish like sardines or mackerel. The scent trail will travel through the deep-sea currents, guiding the shark directly to your lens.

Set your AI triggers for 'motion' with a high sensitivity, but be prepared for 'false positives' from marine snow or drifting debris. Because these sharks move slowly, a lower frame rate (30fps) is usually sufficient for high-quality identification. Ensure your housing is rated for at least 100 bar of pressure to prevent catastrophic failure. The best time for deployment is during periods of calm surface weather to ensure the safe retrieval of your camera rig after its deep-sea mission.

Similar Species

Species that look similar or are commonly confused with Atlantic Sawtail Catshark.

Blackmouth Catshark

The Blackmouth is larger, more widely distributed, and has a significantly darker black interior to its mouth.

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Frequently Asked Questions

Atlantic Sawtail Catsharks live in the 'midnight zone' where sunlight does not penetrate, so they do not follow a traditional day-night cycle. They are active 24/7, though their movements may fluctuate based on deep-ocean currents and the presence of prey.

To attract this species, you need a deep-sea BRUV system baited with oily fish like mackerel. The scent is the primary lure in the dark. Note that these sharks live at depths of 400m+, so they cannot be found in shallow coastal 'backyards'.

They are opportunistic predators that eat a variety of deep-sea creatures, including small shrimp, krill, squid, and tiny bony fish that live along the muddy seafloor.

No, they are never found in suburban or shallow coastal areas. They are exclusive to the deep continental slopes of the Northeast Atlantic and Alborán Sea, hundreds of meters below the surface.

While they look very similar, the Atlantic Sawtail has a slightly shorter snout and a different color inside the corners of its mouth. It is also generally smaller and has a more restricted geographic range than the widespread Blackmouth Catshark.

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