ATLANTIC SAWTAIL CATSHARK
A catshark with a dark mouth and a crest of dermal denticles
The Atlantic Sawtail catshark (Galeus atlanticus) is a little-known species of catshark, belonging to the family Scyliorhinidae, found in the northeastern Atlantic Ocean, centered on the Strait of Gibraltar and the Alborán Sea. It is found on or close to the bottom over the continental slope, mostly at depths of 1,312–1,968 feet. The Atlantic Sawtail catshark closely resembles the Blackmouth catshark and was once considered to be the same species. There are several differences though, including the depth of the caudal peduncle, the color of the furrows and the length of the snout.
Family: Scyliorhinidae – Catsharks
Common Name– Ground Sharks
Common Name– Catsharks
Status: IUCN Red List NEAR THREATENED
Average Size and Length: Mature males have been measured between 38-42 cm/1.2-1.4 feet. Mature females have been measured between 40-45 cm/1.3-1.5 feet. The maximum recorded has been 45 cm/1.5 feet.
Rey and colleagues (2010) reported the smallest mature males and females in their study to be 33 cm/1 foot and 37cm/1.2 feet.
Current Rare Mythical Sightings: The original description of the Atlantic Sawtail catshark, as Pristiurus atlanticus, was published in 1888 by French naturalist Léon Louis Vaillant, in Expéditions scientifiques du “Travailleur” et du “Talisman” pendant les années 1880, 1881, 1882, 1883. Vaillant based his account on a specimen caught at a depth of 540 m/ 1,771 feet off Cape Spartel in northwestern Morocco. They weer previously and long thought to be the same species as the Blackmouth catshark (G. melastomus), until it was resurrected by Ramón Muñoz-Chápuli and A. Perez Ortega in 1985. Castilho and colleagues (2007) further affirmed the distinction between G. atlanticus and G. melastomus using morphometric and mitochondrial DNA data.
Teeth and Jaw: The mouth cavity is black. The mouth is large, wide and curved, with long furrows around the corners. The small teeth each have a narrow central cusp flanked by multiple smaller cusplets on either side.
Head: The head is flattened and the snout is long and angular. The head is proportionately shorter and narrower, and the nostrils relatively farther from the snout tip, than in the Blackmouth catshark. The nostrils are partially covered by triangular flaps of skin on their anterior rims. The eyes are horizontally oval and equipped with nictitating membranes. There is a slight ridge below each eye, and a minute spiracle behind. The eyes are on the lateral edges of the head.
Denticles: There is a distinct crest of enlarged dermal denticles along the upper margin of the tail. The skin is covered by dermal denticles, each with a leaf-shaped crown bearing a median ridge and three marginal teeth.
Tail: The tail is elongated. The caudal has a dark margin and is not black-tipped. The caudal peduncle is compressed from side to side. Its height is greater than in the Blackmouth catshark, exceeding 4.5% of the total length. The caudal fin is low, with a small lower lobe and a ventral notch near the tip of the upper lobe.
Demographic, Distribution, Habitat, Environment and Range: The Atlantic Sawtail catshark can be found in the northeast Atlantic and the Mediterranean in Spain around the Straits of Gibraltar and possibly to Mauritania and Italy. It is most abundant in the center of the Alborán Sea, and around Isla de Alborán. Its total range has been estimated to encompass 19,000 square miles, about evenly divided between the northeastern Atlantic and the western Mediterranean. They are found on the continental slopes between 1,312–1,968 feet. They are bathydemersal. There was a single account of one spotted at 160 feet.
Aesthetic Identification: The Atlantic Sawtail catshark is grey dorsally, and whitish ventrally. There are dark grey blotches and saddles or narrow vertical bars along the body and the tail (rarely are they absent). The pectoral fins are large, wide and with rounded corners. There are angular dorsal fins that are dusky with light rear webs. The first dorsal fin is positioned over the latter portion of the pelvic fin bases, while the second is positioned over the latter portion of the anal fin base. The short, low pelvic fins are placed close to the anal fin. The anal fin is long and low.
Biology and Reproduction: They are oviparous. They apparently have multiple ovipary, there were nine egg cases found in one female. This suggests that the hatching period is short and outside the mother. Mating and spawning occur year-round.
The tough egg case is flask-shaped and reddish, with a rounded bottom and a pair of horns at the top, and measuring around 3.1–3.8 cm/1.2–1.5 inches long and 1.1–1.3 cm/0.43–0.51 inches across. The egg case of the Blackmouth catshark is similar in appearance but significantly larger.
Behavioral Traits, Sensing and Intelligence: Unknown.
Atlantic Sawtail Catshark Future and Conservation: They are currently near threatened. They have been caught incidentally by commercial deep-water fisheries throughout its range, but the impact of fishing pressure on its population is uncertain, but given its restricted range they are classified as near threatened.
Atlantic Sawtail Catshark Recorded Attacks on Humans: Not a threat to humans.