Tony Wu / Whitespotted bamboo sharks (Chiloscyllium plagiosum) pair mating with the male above, insertion of right clasper clearly visible. Kannoura, Shikoku, Kochi-ken, Japan

Tony Wu / Whitespotted bamboo sharks (Chiloscyllium plagiosum) pair mating with the male above, insertion of right clasper clearly visible. Kannoura, Shikoku, Kochi-ken, Japan

Doug Perrine / Plownose chimaera (Callorhinchus milii) captive, showing eye, head clasper to grasp female when mating and electro-recteptors (ampullae of Lorenzini) Victoria, Australia.

Doug Perrine / Plownose chimaera (Callorhinchus milii) captive, showing head clasper to grasp female when mating and electro-recteptors (ampullae of Lorenzini) Victoria, Australia.

Norbert Wu / Spotted Ratfish (Hydrolagus colliei) claspers of male for use in mating, Alaska

Pascal Kobeh / Close-up of the two claspers of Sand tiger shark / Grey nurse shark (Carcharias taurus) Kwazulu-Natal, South Africa

David Fleetham / Close look at the claspers on a male Blacktip reef shark, (Carcharhinus melanopterus) Yap, Micronesia.