Nick Hawkins / Ocean sunfish (Mola mola) off Halifax, Nova Scotia, Canada. July.

Gary Bell/ Oceanwide / Porcupinefish (Diodon nicthemerus) in defensive posture, Port Phillip Bay, Mornington Peninsula, Victoria, Australia

Juergen Freund / Globefish (Diodon nicthemerus) swimming past a mass of plastic moving in the current, North Sulawesi, Indonesia.

Sue Daly / Ocean sunfish (Mola mola) , Sark, British Channel Islands, UK, September.

Franco Banfi,Franco Banfi / Ocean Sunfish (Mola Mola) with Longfinned bannerfish (Heniochus acuminatus) Crystal Bay, Nusa Penida, Bali Island, Indonesia, Pacific Ocean

Alex Mustard / Spotted porcupinefish (Diodon hystrix) swimming in open water above a coral reef, West Bay, Grand Cayman, Cayman Islands, British West Indies, Caribbean Sea.

Georgette Douwma / Black-blotched Porcupinefish / Short-spine Porcupinefish (Diodon liturosus) and a Klein's butterflyfish (Chaetodon kleinii) sheltering in barrel sponge. Komodo National Park, Indonesia.

Claudio Contreras / Balloon fish (Diodon holocanthus) with defensive spines, Puerto Morelos National Park, Caribbean Sea, Mexico, January

Jeff Rotman / Black Blotched Porcupinefish (Diodon liturosus) inflated swimming in open ocean. Sipadan Islands, South China Sea.

Flip Nicklin / Long-spine Porcupinefish (Diodon holocanthus) in defense posture, North America

Fred Bavendam / Porcupinefish (Diodon nicthemerus) swallows water to puff itself up and points its spines outward as a defense against predators, South Australia

Juergen Freund / Balloonfish (Diodon holocanthus). Caribbean