1. Six- and Sevengill Sharks Hexanchidae

2. Diagnostic Features Body cylindrical and moderately slender to snout with no abdominal keels Body cylindrical and moderately slender to snout with no abdominal keels 6 or 7 pairs of gill slits not connected across throat 6 or 7 pairs of gill slits not connected across throat Mouth subterminal on snout Mouth subterminal on snout Teeth in upper and lower jaws differentiated Teeth in upper and lower jaws differentiated Anal fin smaller than dorsal Anal fin smaller than dorsal Caudal fin with strong subterminal notch Caudal fin with strong subterminal notch Can be 4.5’ to 16’ max length at maturity Can be 4.5’ to 16’ max length at maturity

3. Teeth Structure

4. Habitat and Distribution Boreal and cold temperate to tropical seas Boreal and cold temperate to tropical seas Most species deepwater, some in bays and close inshore Most species deepwater, some in bays and close inshore

5. Feeding Habits Sharks Sharks Rays Rays Large bony fishes Large bony fishes Crustaceans Crustaceans Carrion—sometimes mammals Carrion—sometimes mammals

6. Ecology Ovoviviparous Ovoviviparous –6-12 pups per litter –Lack yolk-sac placenta

7. Genera Hexanchus Hexanchus Heptranchius Heptranchius Notorynchus Notorynchus

8. Hexanchus Head broad or narrow and pointed Head broad or narrow and pointed Six pairs of gill slits Six pairs of gill slits No spots on body No spots on body No black tipped fins No black tipped fins Max length: 6’ to 16’ Max length: 6’ to 16’

9. Heptranchias Head narrow, pointed Head narrow, pointed Seven pairs of gill slits Seven pairs of gill slits Large eyes Large eyes Mouth narrow and parabolic (bowl shaped) Mouth narrow and parabolic (bowl shaped) Spots absent from body Spots absent from body Caudal peduncle long Caudal peduncle long Black-tipped fins very noticeable in juveniles Black-tipped fins very noticeable in juveniles Max length: 4.5’ Max length: 4.5’

10. Notorynchus Head broad and rounded or bluntly pointed Head broad and rounded or bluntly pointed Seven pairs of gill slits Seven pairs of gill slits Small eyes Small eyes Mouth wide and arc-ed Mouth wide and arc-ed Caudal peduncle short Caudal peduncle short Body with small black spots Body with small black spots Dorsal and upper caudal lobe without black tips Dorsal and upper caudal lobe without black tips Max length: 10’ Max length: 10’

11. Related Articles ADNET S (2006) Biometric analysis of the teeth of fossil and Recent hexanchid sharks and its taxonomic implications. Acta Palaeontologica Polonica: Vol. 51, No. 3 pp. 477-488. ADNET S (2006) Biometric analysis of the teeth of fossil and Recent hexanchid sharks and its taxonomic implications. Acta Palaeontologica Polonica: Vol. 51, No. 3 pp. 477-488. DUNBRACK R and ZIELINSKR (2005) Body size distribution and frequency of anthropogenic injuries of Bluntnose Sixgill Sharks, Hexanchus griseus, at Flora Islets, British Columbia. Canadian Field- Naturalist: Vol. 119, No. 4 pp. 537-540. DUNBRACK R and ZIELINSKR (2005) Body size distribution and frequency of anthropogenic injuries of Bluntnose Sixgill Sharks, Hexanchus griseus, at Flora Islets, British Columbia. Canadian Field- Naturalist: Vol. 119, No. 4 pp. 537-540. LUCIFORA LO, et al (2005) Reproduction, abundance and feeding habits of the broadnose sevengill shark Notorynchus cepedianus in north Patagonia, Argentina. Marine Ecology- Progress Series: Vol. 289, pp. 237-244. LUCIFORA LO, et al (2005) Reproduction, abundance and feeding habits of the broadnose sevengill shark Notorynchus cepedianus in north Patagonia, Argentina. Marine Ecology- Progress Series: Vol. 289, pp. 237-244. MAISEY JG (2004) Morphology of the Braincase in the Broadnose Sevengill Shark Notorynchus (Elasmobranchii, Hexanchiformes), Based on CT Scanning. American Museum Novitates: Vol. 3429, No. 1 pp. 1–52. MAISEY JG (2004) Morphology of the Braincase in the Broadnose Sevengill Shark Notorynchus (Elasmobranchii, Hexanchiformes), Based on CT Scanning. American Museum Novitates: Vol. 3429, No. 1 pp. 1–52.

12. Works Cited Compagno, L.J.V., 1984. FAO species catalogue. Vol. 4. Sharks of the world. An annotated and illustrated catalogue of shark species known to date. Part 1 - Hexanchiformes to Lamniformes. FAO Fish. Synop. 125(4/1):1-249. Compagno, L.J.V., 1984. FAO species catalogue. Vol. 4. Sharks of the world. An annotated and illustrated catalogue of shark species known to date. Part 1 - Hexanchiformes to Lamniformes. FAO Fish. Synop. 125(4/1):1-249.