Frilled shark (Chlamydoselachus anguineus)
The little-known, deepwater-dwelling frilled shark (Chlamydoselachus anguineus) is one of the most primitive species of living shark. The species name anguineus, which derives from the Latin for snakelike, only partly conveys its bizarre appearance. The head is lizard-like and features a blunt-ended snout and a very large mouth armed with multiple rows of sharp, three-pronged teeth. While each tooth is relatively small, there are around 300 in total, providing almost a thousand sharp hooks on which to trap struggling prey. Behind the head, on both sides of the body, there are six gill slits, which each possess a distinctive frilly margin. The front slits on each side extend beneath the body, meeting under the throat, giving the appearance of a frilly collar. The body is dark brown or grey in colour, with a large anal fin and small, paddle-shaped pectoral fins, while the dorsal fin is relatively small and set very far back on the body. The caudal fin has a small, vestigial lower lobe, while in contrast, the upper lobe is very elongated, and further extends the serpentine body.