This sharks tail has distinctive pattern

The Flagtail swellshark (Cephaloscyllium signourum) is a little-known species of catshark, belonging to the family Scyliorhinidae. They can be found in northeastern Queensland, Australia at depths between 1,575-2,297 feet. They have a variegated color pattern. Like other swellsharks, the Flagtail swellshark can inflate its body with water (or air on land) in an effort to deter potential predators.


Family: Scyliorhinidae – Catsharks

Genus: Cephaloscyllium

Species: signourum


Phylum– Chordata

Class– Chondrichthyles


Common NameGround Sharks

Family– Scyliorhinidae

Common NameCatsharks




Average Size and Length: They reach a length of at least 74 cm/2.4 feet.

Current Rare Mythical Sightings: In 1994, Commonwealth Scientific and Industrial Research Organization (CSIRO) chief researchers Peter Last and John Stevens recognized an undescribed Australian swellshark with a variegated color pattern, which they provisionally named Cephaloscylliumsp. E“. Later investigation revealed that “sp. E” in fact constituted two species: The Speckled swellshark (C. speccum) and the Flagtail swellshark, which was formally described in a 2008 CSIRO publication by Peter Last, Bernard Séret, and William White.

Because of its distinctive caudal fin marking, it was given the specific epithet signourum from the Latin signum (“flag”) and the Greek oura (“tail”).

The type specimen is a 74 cm/ 2.4 feet long female collected at the Lihou Reef and Cays, near Queensland.

Teeth and Jaw: The mouth is large, short and wide, without furrows at the corners. There are 84 upper tooth rows and 97 lower tooth rows. Most of the small teeth have three cusps with the central cusp the longest; the teeth toward the jaw corners may also have 1–2 additional lateral cusplets. The upper teeth are exposed when the mouth is closed.

Head: The head is short, broad and flattened. The snout is rounded, with nostrils preceded by laterally enlarged skin flaps that do not reach the mouth. The slit-like eyes are positioned high on the head, and are followed by tiny spiracles.

Denticles: The body is densely covered by small, overlapping dermal denticles with a median ridge and a single cusp, though a few may be three-cusped.

Tail: 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 Flagtail swellshark is found off of northeastern Queensland, Australia and possibly surrounding islands at a depth of between 1,575-2,297 feet. They have been reported from Murray Island and Lihou Reef. It is not confirmed if other reports in other locations are the same species. They are bottom-dwelling. They are considered tropical benthopelagic.

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

Aesthetic Identification: The Flagtail swellshark has a stout body. Adult Flagtail swellsharks have a variegated brown coloration with 9–10 darker dorsal saddles and “V”-shaped blotch at the tip of the upper caudal fin lobe. Juveniles are yellow with narrow brown bars instead of saddles, and a distinctive marking between the spiracles shaped like two loops connected by a line. The ventral side is plain whiteish. 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 large and broad, with somewhat pointed tips and nearly straight trailing margins. The first dorsal fin has a narrowly rounded apex and originates over the front half of the bases of the small pelvic fins. The second dorsal fin is smaller and lower than the first, originating before the anal fin origin. The anal fin is much larger and deeper than the second dorsal fin.

THIS IS THE HOLOTYPE DATA: The head 7.5% TL in height, trunk 16.3% TL in width; origin of first dorsal-fin is over the anterior pelvic-fin base; prenarial 3.6% TL in length; preorbital snout length is 2.0 times prenarial length, 3.0 in prepectoral length, 6.6 in prepelvic length; snout-vent length long, 51.7% TL; nostril width 2.7% TL; eye-spiracle space narrow, 0.5% TL; pectoral fin medium-sized, its height 12.8% TL, posterior margin 11.9% TL; anal fin tall, 4.0% TL; anal-caudal space is 5.0% TL; precaudal length is 76% TL; interdorsal space is 6.6% TL; teeth with 3 well-developed cusps near symphysis of upper jaw; mostly unicuspidate flank denticles; back without the greatly enlarged denticles; adult clasper unknown; vertebral centra 115-116; tooth count high, 84 teeth in upper jaws, 97 in lower jaws; color of upper half of body medium brown, with a variegated pattern that is not clearly demarcated from the ventral surface; dark saddles (10) evident on body and tail; dorsal fins are pale variegated; dark blotch absent over gills; marking on posterior margin of terminal lobe of caudal fin dark, anteriorly directed, V-shaped; upper surface of pectoral-fin with a dark brown central blotch; centered over ventral origin of caudal fin is a well-developed saddle; ventral surface is uniformly greyish or white in color; juveniles are pale with dark transverse markings appearing as narrow bars and hollow saddles; markings between spiracles not separated into two unconnected pseudo-ocelli.

Biology and Reproduction: More than likely they are oviparous.

Behavioral Traits, Sensing and Intelligence: Like other members of its genus, the Flagtail swellshark can expand its body with water (or air on land) to appear larger in an effort to ward of potential predators.

Speed: More than likely they are slow and sluggish.

Flagtail Swellshark Future and Conservation: Not enough data to evaluate.

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