Another rare Australian catshark

The Speckled swellshark (Cephaloscyllium speccum) is a little-known species of catshark belonging to the family Scyliorhinidae, with a patchy distribution in northwestern Australia. The northeastern sightings are actually a separate species. As its common name suggests, its color pattern consists of many dark spots and white-spotted dark saddles and blotches on a light gray background. The juveniles are yellow with dark spots and lines, and distinctive ocelli, or eyespot-like marks behind each eye. Like other swellsharks, this species can inflate itself in an effort to deter predators when they feel threatened.


Family: Scyliorhinidae – Catsharks

Genus: Cephaloscyllium 

Species: speccum


Phylum– Chordata

Class– Chondrichthyles


Common NameGround Sharks

Family– Scyliorhinidae

Common NameCatsharks




Average Size and Length: Mature males have been measured at 64 cm/2.1 feet. They can reach at least 68 cm/2.2 feet.

Current Rare Mythical Sightings: In 1994, Commonwealth Scientific and Industrial Research Organisation (CSIRO) chief researchers Peter Last and John Stevens provisionally gave the name Cephaloscylliumsp. E” to an undescribed Australian swellshark with a variegated color pattern. Later investigation revealed that “sp. E” in fact constituted two species: the Flagtail swellshark (C. signourum) and the Speckled swellshark, which was formally described in a 2008 CSIRO publication by Peter Last, Bernard Séret, and William White. Its specific epithet is derived from the Latin specca, meaning “speckled”. The type specimen is a 68 cm/2.2 feet long adult male collected from Rowley Shoals off Western Australia.

Teeth and Jaw: The mouth is long and arched. There are no labial furrows. The tooth rows number 69–84 in the upper jaw and 74–97 in the lower jaw. The upper teeth are exposed when the mouth is closed. Large sharks have 5-cusped teeth while small sharks have 3-cusped teeth. The central cusp is by far the largest and is longer in adult males than in adult females.

Head: The head is short, broad and flattened. The head is between 7.8-12.5% in total length in height. The snout is blunt, with the nostrils preceded by laterally expanded skin flaps that do not reach the mouth. The slit-like eyes are positioned high on the head and are followed by tiny spiracles. The mouth reaches past the front end of the eyes. The eyes are cat-like. There are ridges over the eyes. The prenarial is between 3.6-4.9% of the total length, in length. The preorbital snout length is 1.5-2.0 times prenarial length. The snout-vent length is long, 47.4-51.1% of the total length. The nostril is 2.2-2.7% of the total length, in width. The eye-spiracle space is narrow, 0.4-1.0% of the total length.

Denticles: The body is densely covered by small, overlapping arrowhead-shaped dermal denticles with a median ridge. They are unicuspidate or weakly tricuspidate flank denticles. The back is without greatly enlarged denticles.

Tail: The tail is short. The caudal fin has a distinct lower lobe and a strong ventral notch near the tip of the upper lobe.

Demographic, Distribution, Habitat, Environment and Range: The Speckled swellshark has a patchy record from tropical northwest Australia from Rowley Shoals to Ashmore Reef. They are found on the continental slope between 1,280-1,444 feet. Previously, records from the northeast were thought to be the Speckled swellshark, but are in fact the Flagtail swellshark. They are considered benthopelagic.

Ram-Suction Index: More than likely high on the suction side of the index.

Aesthetic Identification: The Speckled swellshark has a pale greyish upper surface with intense mottling of small, dark blotches, and larger botches and saddles with small white spots. There are rounded blotches and white spots below the eyes followed by 3 pre-dorsal saddles. The fins are mostly pale with darker spots and blotches. The Speckled swellshark is stalky, with an inflatable stomach. The fourth and fifth pairs of gill slits lie over the pectoral fin bases and are shorter than the first three. The pectoral fins are moderate in size, with somewhat pointed tips and nearly straight trailing margins the height is between 8.9-13.8% of the total length and the posterior margin is between 8.5-13.3% of the total length. The pelvic fins are small, with short claspers in males. The interdorsal space is between 6.5-8.6% of the total length. The first dorsal fin has a narrowly curved apex. The second dorsal fin is much smaller than the first dorsal fin, but both dorsal fins are small. The first dorsal fin base is over or behind the pelvic fin bases. The anal fin resembles the second dorsal fin but is larger and deeper. The anal fin is tall, between 3.2-4.4% of the total length. The anal-caudal space is between 4.5-6.1% of the total length. The precaudal is between 76-78% of the total length, in length. The trunk width is between 13.0-16.8% of the total length. It is 2.6-3.1 in prepectoral length, 5.9-7.1 in prepelvic length. The adult claspers are long, the outer length is about 7% of the total length. 

Biology and Reproduction: Unknown, but more than likely oviparous. The vertebral centra count is between 111-115.

Behavioral Traits, Sensing and Intelligence: Like other members of its genus, they have an inflatable stomach that they can fill with water (or air on land) in an effort to appear larger and deter potential predators or threats.

Speed: More than likely sluggish and slow.

Speckled Swellshark Future and Conservation: There is not enough data to evaluate. They are only known from a few specimens and may be rare. They may be subject to little fishing pressure.

Speckled Swellshark Recorded Attacks on Humans: Not a threat to humans.