Tom Vierus / Many-colored fruit-dove (Ptilinopus perousii) female, perched in tree, Turtle Island, Yasawa Islands, Fiji.

Tom Vierus / Many-colored fruit-dove (Ptilinopus perousii) female, perched in tree with a berry in beak, Turtle Island, Yasawa Islands, Fiji.

Joel Sartore / Photo Ark / Many-colored fruit dove (Ptilinopus perousii) male profile, Toledo Zoo. Captive.

Jane Burton / Balloon fish {Diodon holocanthus} inflated in self-defence. Captive.

Jane Burton / Balloon fish {Diodon holocanthus} one inflated in self-defence. Composite, Captive

Constantinos Petrinos / Broadclub cuttlefish {Sepia latimanus} deimatic display, defence, gives illusion of

Mark Brownlow / White doves in trance, lying on back, feigning death in self defence. When line drawn from their beak they fall into a trance

Juergen Freund / Leopard sea cucumber extrudes toxic tentacles in self defence

Jiri Lochman / Short-beaked echidna (Tachyglossus aculeatus acanthion) digging itself into the ground as means of self-defence, Dryandra Forest, Western Australia.