Kim Taylor / Brine shrimp {Artemia salina} male showing claspers

Jeff Rotman / Close up view of male reproductive organ 'Claspers' of Whitetip Reef Shark (Triaenodon obesus) Cocos Island, Costa Rica, Pacific Ocean.

Nick Upton / Male Banded demoiselle damselfly (Calopteryx splendens) gripping female with tail claspers before flying off in tandem and mating, Wiltshire, UK, May

Nick Upton / Male Banded demoiselle damselfly (Calopteryx splendens) gripping female with tail claspers as she prepares to mate in wheel position, Wiltshire, UK, May

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

Doug Perrine / Male Sand tiger shark showing claspers and lateral line {Carcharias taurus} Grey nurse

Kim Taylor / Brine shrimp {Artemia salina} male showing claspers. Captive.

Kim Taylor / Brine shrimp {Artemia salina} male clasping egg laden female

JEFF FOOTT / Male Fiddler crab {Uca pugilator} Mangroves, Florida, USA. Note enlarged claw

Jeff Rotman / Claspers on male Iago shark (Iago omanensis) Red Sea Deep sea shark at 500m depth

Jeff Rotman / Claspers (penis) of Epaulette Shark {Hemiscyllium ocellatum} Australia, Pacific

TOM WALMSLEY / Close up of claspers (male sex organs) of Sand tiger / Raggedtooth shark {Carcharias taurus} Cape Peninsular, South Africa