The African Sawtail catshark (Galeus polli) is a species of catshark belonging to the family Scyliorhinidae. They are found at depths of 522-2,362 feet off the western African coast from Morocco to South Africa. They are slender with a long, pointed snout, a series of dark saddles along the back and tail, and a prominent crest of enlarged dermal denticles along the upper edge of the caudal fin. Its maximum known length is 46 cm/1.5 feet. The African Sawtail catshark is the only known member of its genus to be ovoviviparous.
Family: Scyliorhinidae – Catsharks
Common Name– Ground Sharks
Common Name– Catsharks
Average Size and Length: They are born between 10-12 cm/3.9-4.7 inches. Adolescent males have been measured between 27-32 cm/10.6-12.6 inches. Adolescent females have been measured between 29-38 cm/11.4 inches-1.2 feet. Mature males have been measured between 30-46 cm/11.8 inches-1.5 feet. Mature females have been measured between 30-43 cm/11.8 inches-1.4 feet. The longest recorded has been 46 cm/1.5 feet.
Current Rare Mythical Sightings: Taxonomy: In 1953, Belgian ichthyologist Max Poll published a report on sharks and chimaeras captured during a 1948–49 Belgian oceanographic expedition off western Africa, including several seemingly ovoviviparous Blackmouth catsharks (G. melastomus). As the Blackmouth catshark is known to be oviparous, Poll’s account alerted French zoologist Jean Cadenat to the presence of a distinct catshark species in the region. After examining more specimens from Senegal, Cadenat described the new species in a 1959 issue of the scientific journal Bulletin de l’Institut Francais d’Afrique Noire (Sér A) Sciences Naturelles, naming it in Poll’s honor.
Teeth and Jaw: The mouth lining is dark. The mouth is large, wide, and arched, with well-developed furrows at the corners. The teeth have a central cusp and 1–2 pairs of smaller lateral cusplets.
Head: They have a flattened head, and a long-pointed snout. The anterior rim of each nostril has a triangular flap of skin. The eyes are horizontally oval with nictitating membranes. There are no ridges underneath. Tiny spiracles are located behind the eyes.
Denticles: There is a distinct crest of enlarged dermal denticles along the upper margin of the tail. They are not on the lower margin. The dermal denticles are small and overlapping, each with three-toothed crown that has a median ridge.
Tail: The tail is elongated. The caudal peduncle is compressed from side to side and leads to a low caudal fin with a small lower lobe and a ventral notch near the tip of the upper lobe.
Demographic, Distribution, Habitat, Environment and Range: The African Sawtail catshark can be found in the eastern Atlantic in southern Morocco to South Africa on the west coast (26°N – 26°S). They are found on the upper continental slope and outer continental shelf in deep water between 522-2,362 feet, and can tolerate low levels of oxygen. It is most common at depths of 846-1,608 feet. They are considered bathydemersal. They are abundant off the coast of Namibia to the Northern Cape Province of South Africa, and rare south of the Orange River.
Diet: They eat small fish (lanternfishes, hakes, grenadiers, rockfishes and lightfishes), squid and shrimp and other crustaceans.
Aesthetic Identification: The African Sawtail catshark is somewhat small and slender with usually 11 or less well-defined dark grey or blackish-grey saddle blotches outlined in whiteish on the back and the tail. They are sometimes uniform dark above. There are no black dorsal and caudal fin tips. There are 5 gill slits. The two dorsal fins are blunt-tipped and similar in size. The first dorsal fin is positioned over the rear of the pelvic fins and the second over the rear of the anal fin. The pectoral fins are large and broad with rounded corners, while the pelvic and anal fins are elongated and more angular. The anal fin base is close to the pelvic and caudal fins and measures 14–17% of the total length, much greater than the distance between the dorsal fins.
Biology and Reproduction: They are the only known member of their genus to be ovoviviparous, or aplacental viviparous, having 6-12 pups per litter. Reproduction is year-round. Adult females have two functional uteruses.
The developing embryos are initially sustained an external yolk sac, and emerge from the egg at between 2.4 and 2.8 cm/0.94 and 1.10 inches long. Pigmentation begins to develop at an embryonic length of 5 cm/2.0 inches. At around 6 cm/2.4 inches long, the embryos have well-developed external gills, which largely disappear by the time they are 10 cm/3.9 inches long. Near-term fetuses weigh over twice as much as eggs, suggesting some form of secondary maternal provisioning during gestation. (Cadenat, J. (1959). “Notes d’ichtyologie ouest-africaine. XX. Galeus polli espèce nouvelle ovovivipare de Scylliorhinidae“. Bulletin de l’Institut Francais d’Afrique Noire (Sér A) Sciences Naturelles. 21 (1): 395–409).
Behavioral Traits, Sensing and Intelligence: They are known to tolerate low levels of oxygen.
African Sawtail Catshark Future and Conservation: They are currently of least concern. Only the shallow part of its range is heavily fished. It is small and easily escapes trawls. They are on occasion utilized for meat or fishmeal.
African Sawtail Catshark Recorded Attacks on Humans: Not a threat to humans.