NARROWBAR SWELLSHARK

Taxonomy:

Phylum– Chordata

Class– Chondrichthyles

Order– Carcharhiniformes

Common Name– Ground Sharks

Family– Scyliorhinidae

Common Name– Catsharks

Genus– Cephaloscyllium

Species– zebrum

Status: IUCN Red List DATA DEFICIENT

Average Size and Length: They reach at least 43 cm/1.4 feet.

Current Rare Mythical Sightings: In 1994, Commonwealth Scientific and Industrial Research Organisation (CSIRO) chief researchers Peter Last and John Stevens applied the provisional name Cephaloscyllium “sp. D” to two striped swellsharks trawled from Flinders Reef in December 1985. One was a 44.5 cm/17.5 inches long male, and the other a 43.5 cm/17.1-inch-long female. In 2008, this species was formally described by Peter Last and William White in a CSIRO publication, and given the specific epithet zebrum in reference to its unique color pattern. The male specimen was designated as the holotype and the female a paratype.

Teeth and Jaw: The mouth is long and narrow. There are no furrows at the corners of the mouth. The tooth rows number 60–61 in the upper jaw and 59–62 in the lower jaw. The teeth are small, most having three cusps in the male specimen and five cusps in the female specimen near the symphysis of the upper jaw. The upper teeth are exposed when the mouth is closed.

Head: The head is short and broad. The snout is rounded, with the nostrils preceded by laterally expanded skin flaps that do not reach the mouth. The head is between 10.2-11.1% of the total length in height. The prenarial is between 4.4-4.8% of the total length, in length. The preorbital snout length is 1.5 times prenarial length. The snout-vent, 49.4-50.3% of total length, in length. The nostril is 2.2-2.4% T of total length in width. The eye-spiracle space is wide, between 1.1-1.3% of total length. There are ridges over the eyes. The eyes are slit-like and are placed high on the head and followed by tiny spiracles.

Denticles: The body is densely covered by fine, arrowhead-shaped dermal denticles bearing median and lateral ridges.

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

Demographic, Distribution, Habitat, Environment and Range: The Narrowbar swellshark can be found in northeast Australia, recorded from the continental slope at 1, 444 feet. The specimens were collected from Flinders Reef. They are considered tropical bathypelagic.

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

Aesthetic Identification: The Narrowbar swellshark has a very distinct pattern of numerous narrow closely spaced dark bars on a dark brownish to cream colored background. The body is stalky. The bars do not join to form rings or saddles. There are 17-18 of these bars present pre-dorsally. There are irregular lines on the snout. The fins, and the ventral side are uniformly pale. They have an inflatable stomach. The fourth and fifth gill slits lie over the pectoral fin and are shorter than the first three. It is between 2.8-2.9 in prepectoral length, and about 6.3 in prepelvic length. The pectoral fins are broad and moderate in size, with narrowly rounded tips. The first dorsal fin is triangular, and set behind the pelvic fins. The second dorsal fin is much smaller than the first, and much smaller. It sits over the anal fin. The pelvic fins are small, with elongate claspers in males. The anal fin is rounded and much larger and deeper than the second dorsal fin. The trunk is narrow, its width is between 14.7-15.7% of the total length. The height of the pectoral fin is between 11.3-12.1% of the total length. The posterior margin length is between 10.6-11.6% of the total length. The height of the anal fin is between 3.2-3.3% of the total length. The anal-caudal space is about 5.4% of the total length. The precaudal length is between 75-76% of the total length. The interdorsal space is between 6.2-7.7% of the total length. The adult clasper is long, up to 8.2% of the total length, almost reaching the anal fin, with an interspace about 3.9 in the anal-fin base.

Biology and Reproduction: Unknown, but more than likely oviparous. The vertebral centra is between 110-111.

Behavioral Traits, Sensing and Intelligence: They have inflatable stomachs that they use to expand their bodies by filling themselves with water or air (on land), to appear bigger to potential predators.

Speed: More than likely they are sluggish.

Narrowbar Swellshark Future and Conservation: There is not enough data to evaluate. They are only known from a few specimens trawled from one location. They are subjected to minimal fishing pressure. 

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