A unique spurdog with 1 and 3 point cusped dermal denticles
Family: Squalidae – Dogfish Sharks
Common Name– Dogfish Sharks
Common Name– Dogfish Sharks
Status: IUCN Red List DATA DEFICIENT
Average Size and Length: The Bighead spurdog reaches 1.1 feet in length.
Current Rare Mythical Sightings: A newly discovered species, the first specimens of the Bighead spurdog were collected during South Pacific biodiversity surveys conducted by the Institut de recherche pour le développement (IRD). The Bighead spurdog was described by Peter Last, Bernard Séret, and John Pogonoski in a 2007 Commonwealth Scientific and Industrial Research Organisation (CSIRO) publication.
Teeth and Jaw: The mouth is nearly straight and has long furrows at the corners. There are 26–27 upper and 22–24 lower tooth rows. Each tooth has a single angled, knife-like cusp.
Head: The Bighead spurdog has an extremely broad head with a hump behind it. The snout is short and triangular with a blunt tip. The nostrils have skin flaps. The eyes are oval, medium sized, and have a notch in the outside corner; behind them are small, crescent-shaped spiracles.
Denticles: The dermal denticles of the Bighead spurdog are unique. Some of the dermal denticles are 1-pointed cusps, and others are 3-pointed cusps. This mix is seen in adult sharks, and is extremely unique. The dermal denticles do not overlap and are tiny.
Tail: There are lateral keels on the caudal peduncle. The caudal fin is asymmetrical, with a long upper lobe and a well-developed lower lobe; the trailing margins of both lobes are convex.
Demographic, Distribution, Habitat, Environment and Range: The Bighead spurdog has only been recorded from south of New Caledonia, and from seamounts on the Norfolk Ridge in the northern Tasman Sea. It has been caught between the depths of 1,470–2,625 feet.
Aesthetic Identification: The Bighead spurdog has a spindle-shaped, robust and stalky body. There are 5 pairs of gill slits with the fifth pair the longest. It is brown above and counter-shaded light below. The dorsal fins darken towards the apexes. The dorsal fin free rear tips and the caudal fin posterior margin are white. It has 2 dorsal fins with long spines which have narrowly rounded apexes, short free rear tips and concave posterior margins. The first dorsal fin originates above the pectoral fin insertions; the second is smaller than the first and originates behind the pelvic fins. The pectoral fins are medium-sized with rounded tips, the pelvic fins are small, and there is no anal fin.
Biology and Reproduction: Not much is known about the Bighead spurdog. They are presumably ovoviviparous. Males seem to mature sexually at under 26 inches long.
Behavioral Traits, Sensing and Intelligence: Unknown.
Bighead Spurdog Future and Conservation: Rare and little known, the Bighead spurdog is sometimes caught as bycatch from longline fisheries. There is not enough data to evaluate.
Bighead Spurdog Recorded Attacks on Humans: Not a threat to humans.
A newly discovered species by:
Last, P.R.; Séret, B.; Pogonoski, J.J. (2007). “Squalus bucephalus sp. nov., a new short-snout spurdog from New Caledonia”. Descriptions of new dogfishes of the genus Squalus (Squaloidea: Squalidae). CSIRO Marine and Atmospheric Research. pp. 23–29.