Morley Read / Close-up of Agua rica leaf frog (Phyllomedusa ecuatoriana) eggs after 11 days development, showing beating heart and blood flowing over gills, Ecuador. Endangered. (non-ex)

Nigel Cattlin / Immature caterpillar of a codling moth (Cydia pomonell) eating its way through a gallery in a ripening apple fruit, Berkshire, July

Morley Read / Developing embryo of the Ecuadorian monkey frog (Phyllomedusa ecuatoriana), showing heart beating and blood flowing, Morona Santiago Province, Ecuador, (non-ex)

Pete Oxford / Glass Frog (Hyalinobatrachium aureoguttatum) underside showing internal organs, native to South America

Pete Oxford / Glass Frog (Hyalinobatrachium aureoguttatum) underside showing internal organs, native to South America

Pete Oxford / Glass Frog (Hyalinobatrachium aureoguttatum) underside showing internal organs, native to South America

Juergen Freund / Green urn sea squirt / tunicate (Didemnum molle) internal detail. Misool, Raja Ampat, West Papua, Indonesia.

Stephen Dalton / Two Water Fleas (Daphnia sp.), showing transparency of bodies and internal organs. UK, September.

Pete Oxford / Northern Glassfrog (Hyalinobatrachium fleischmanni) underside showing internal organs, northwest Ecuador

Graham Eaton / An underwater view of a mountain stream showing internal reflections on the water surface, Snowdonia NP, Gwynedd, Wales, UK, December 2009.

Juergen Freund / X-ray of the shell of the Pearly / Chambered nautilus {Nautilus pompilius} showing the internal chambers of the shell.

Nigel Cattlin / Doyenne du Comice pear (Pyrus communis) fruit with deformity and internal hard growth caused by Pear stony pit virus, cross section. Berkshire, England, UK. October.