The Pygmy Ribbontail catshark (Eridacnis radcliffei) is a species of Finback catshark, belonging to the family Proscylliidae. It is distributed patchily in the western Indo-Pacific from Tanzania to the Philippines. It can be found in and around muddy bottoms, around the edges of continental and insular shelves at a depth of 232-2,513 feet. It ranks at a tie for 3rd place at 24 cm/9.4 inches in the PSD ranked World’s Smallest Sharks. It has a slender body with a low, ribbon-like tail fin, and is dark brown in color with blackish dorsal fin markings and tail bands.

Family: Proscylliidae – Finback Catsharks

Genus: Eridacnis 

Species: radcliffei


Phylum– Chordata

Class– Chondrichthyles


Common NameGround Sharks

Family– Proscylliidae

Common NameFinback Catsharks




Average Size and Length: They are born around 11 cm/4.3 inches. Mature males have been measured around 18-19 cm/7 inches, and adult females around 15-16 cm/6 inches. The maximum recorded has been 24 cm/9.4 inches. It is one of the smallest species of sharks. It ties for 3rd place in our PSD ranked World’s Smallest Sharks. To read more on the PSD World’s Smallest Sharks visit here.

Average Weight: One male shark 18.6 cm/7.3 inches long weighed 14 g/0.49 ounces and a pregnant female 24.2 cm/9.5 inches long weighed 37 g/1.3 ounces.

Current Rare Mythical Sightings: The first known specimens of the Pygmy Ribbontail catshark were collected during the 1907–1910 Philippine Expedition of the U.S. Fish Commission Steamer Albatross. Hugh McCormick Smith, Deputy Fish Commissioner and director of the expedition, published a description of this shark in a 1913 issue of the Proceedings of the United States National Museum, naming it for the expedition’s General Assistant and Naturalist Lewis Radcliffe, and creating for it the new genus Eridacnis. The type specimen is a 23 cm/9.1-inch-long adult female caught off Jolo Island in the Sulu Archipelago, Philippines.

Teeth and Jaw: The mouth is wide and V-shaped, without furrows at the corners and containing numerous rows of small, multi cusped and pointed teeth that become more comb or burr-like towards the sides. There are papillae on the roof of the mouth.

Head: It has a short, rounded snout and elongated, oval eyes with nictitating membranes. Each nostril is preceded by a short, triangular flap of skin.

Tail: They have a long, low, narrow, ribbon-like caudal fin with prominently visible dark banding. It comprises a quarter of the total length or more and lacks a lower lobe.

Demographic, Distribution, Habitat, Environment and Range: The Pygmy Ribbontail catshark can be found in the Indo-west Pacific, in Tanzania, in the Gulf of Aden, in India, in the Andaman Islands, Vietnam, and the Philippines. Its range is quite patchy (22°N – 10°S). They are found in mud, on the upper continental slope on the outer shelves between 232-2,513 feet. They are dep-water bathydemersal.

Diet: They more than likely feed on small bony fish, crustaceans, and squid. In India, one study concluded 55% of their diet was composed of bony fishes that were mainly lanternfishes but also bristlemouths and small eels, 28% of crustaceans that were mainly shrimp but also stomatopods and crab larvae, and 14% of squid, and the remainder of other items including a bivalve. (Nair, R.V. & K.K. Appukuttan (1973). “Observations on the food of deep sea sharks Halaeurus hispidus (Alcock) Eridacnis radcliffei Smith and Iago omanensis Compagno and Springer“. Indian Journal of Fishes. 20 (2): 575–583).

Aesthetic Identification: The Pygmy Robbontail catshark is extremely thin, small and dark brown in color. There are blackish markings on two spineless dorsal fins. There are papillae at the edges of the gill arches. The two dorsal fins are of similar size, the first positioned slightly closer to the pectoral fins than the pelvic fins and the second over the anal fin. The anal fin is less than half the height of the dorsal fins.

Biology and Reproduction: They are ovoviviparous, having one or two very large pups per litter. They more than likely grow fast. Females carry large eggs or have been known to become pregnant at 15 cm/6 inches long, and carry the small embryos are at 17 cm/7 inches, though only females over 18 cm long have been found with fully developed fetuses. This is the reason researchers believe they grow relatively fast.

Current research suggests they are possibly capable of fluorescence. Read more about PSD Glow in the Dark Sharks here.

Behavioral Traits, Sensing and Intelligence: Unknown.

Speed: They are more than likely slow swimming.

Pygmy Ribbontail Catshark Future and Conservation: They are currently of least concern. They are common in southern India and in the Philippines. Pygmy Ribbontail catsharks are captured incidentally in bottom trawls off the Philippines. It is of little commercial interest.

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