Heidi & Hans-Juergen Koch / Greater Spotted Dogfish (Scyliorhinus stellaris) embryo in mermaid's purse egg capsule, native to Atlantic and Mediterranean

Sue Daly / Nursehound (Scyliorhinus stellaris) Sark, British Channel Islands, August.

Adrian Davies / Egg case of Nursehound (Scyliorhinus stellaris) on white background, found on beach in Cornwall, UK, July.

Pete Oxford / Catfish, various species, for sale at market in Georgetown, Guyana, South America

Alex Hyde / Nursehound dogfish (Scyliorhinus stellaris) empty egg cases / mermaid's purse. Anglesey, Wales, UK. December.

Alex Hyde / Nursehound dogfish (Scyliorhinus stellaris) empty egg cases / mermaid's purse. Anglesey, Wales, UK. December.

Alex Hyde / Nursehound dogfish (Scyliorhinus stellaris) empty egg cases / mermaid's purse and a single much samller eggcase from a Smallspotted catshark (Scyliorhinus canicula). Anglesey, Wales, UK. December.

Graham Eaton / Greater / Larger Spotted Dogfish (Scyliorhinus stellaris) caught on a fishing line and being reeled in, Cardigan Bay, Wales, UK, May 2008

Graham Eaton / Bull Huss / Larger Spotted Dogfish (Scyliorhinus stellaris) caught on a fishing line, Cardigan Bay, Wales, UK, May

Geoff Simpson / Eggcase (mermaid's purse) of Larger spotter dogfish {Scyliorhinus stellaris} Wales