Nick Upton / European eel (Anguilla anguilla) elver wriggling up an Eel pass between clumps of nylon bristles on the side of a weir on a drainage channel as it migrates upstream at night, Somerset Levels, UK, Apri...

Nick Upton / European eel (Anguilla anguilla) elver wriggling up an Eel pass between clumps of nylon bristles on the side of a weir on a drainage channel as it migrates upstream at night, Somerset Levels, UK, Jul...

Nick Upton / European eel (Anguilla anguilla) elvers wriggling up an Eel pass between clumps of nylon bristles on the side of a weir on a drainage channel as they migrate upstream at night, Somerset Levels, UK, Ju...

Robert Valentic / Northern death adder {Acanthophis praelongus} male luring prey by wriggling its tail tip, Weipa, Queensland, Australia

Robert Valentic / Barkly death adder {Acanthophis hawkei} female wriggling the tip of its tail (caudal lure) to mimic a grub or worm to attract a lizard within strike range, Northern Territory, Australia

Robert Valentic / Rugose Death Adder (Acanthophis rugosus) male wriggling the tip of its tail (caudal lure) to mimic a grub or worm to attract a lizard within strike range, Darwin, Northern Territory, Australia

Michael & Patricia Fogden / Redtail Coral Snake (Micrurus mipartitus) venomous, defensive tail wriggling display, rainforest, Costa Rica

Espen Bergersen / Walruses (Odobenus rosmarus) hauled out on beach with one rubbing belly on sand, Sarstangen, Svalbard, Norway, August.

Espen Bergersen / Walruses (Odobenus rosmarus) hauled out on beach, with one lying upside down and wriggling to scratch back, Sarstangen, Svalbard, Norway, August.

Neil Aldridge / Tiger leech (Haemadipsa picta) waving front end around in response to movement beside leaf, before detaching rear end from leaf and leaving frame, Danum Valley, Sabah, Borneo, Malaysia.

Jacob Guy / Hairy frogfish (Antennarius striatus) using lure to attract prey as it waits to ambush them, Indonesia, Pacific Ocean.

Jacob Guy / Hairy frogfish (Antennarius striatus) using lure to attract prey as it lies in wait to ambush them on seabed, Indonesia, Pacific Ocean.