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

Nick Upton / Large male White-clawed crayfish (Austropotamobius pallipes) with claspers visible under the tail, caught in a well stocked stream ahead of translocation to an ARK site, safe from Signal crayfish (Pac...

Shane Gross / Nurse sharks (Ginglymostoma cirratum) ready to mate. Showing male claspers, which are used to channel semen into the female during mating, Eleuthera, Bahamas.

Shane Gross / Nurse sharks (Ginglymostoma cirratum) ready to mate. Showing male claspers, which are used to channel semen into the female during mating, Eleuthera, Bahamas.

Tony Wu / Whitespotted bamboo shark (Chiloscyllium plagiosum) working his way into a crevice to approach female to mate. The males two claspers (the organs used for inseminating the female shark) are clearly vi...

Lorraine Bennery / Common blue damselfly (Enallagma cyathigerum) gripping female with tail claspers as she prepares to mate in wheel position, Haut-Rhone Francais National Natural Reserve, France,June.

Lorraine Bennery / Common blue damselfly (Enallagma cyathigerum) gripping female with tail claspers as she prepares to mate in wheel position, Haut-Rhone Francais National Natural Reserve, France, June.

Lorraine Bennery / Common blue damselfly (Enallagma cyathigerum) gripping female with tail claspers as she prepares to mate in wheel position, Haut-Rhone Francais National Natural Reserve, France, June.

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