Nick Garbutt / Aggregation / bloom / swarm of Moon Jellyfish (Aurelia aurita) in the clear waters of Loch Na Keal, off the Isle of Mull, north west Scotland, UK, June, Photographed through the surface.

Gary Bell/ Oceanwide / Jellyfish (Cyanea rosella), Spencer Gulf, South Australia, Australia

Gary Bell/ Oceanwide / Portuguese Man Of War (Physalia physalis) jellyfish, Coffs Harbor, Solitary Islands Marine Park, New South Wales, Australia

Gary Bell/ Oceanwide / Portuguese Man Of War (Physalia physalis) jellyfish, Coffs Harbor, Solitary Islands Marine Park, New South Wales, Australia

Jordi Chias / Jellyfish (Diplulmaris antarctica). Cuverville, Antarctic Peninsula, Antarctica.

Alex Mustard / Jellyfish (Catostylus sp.) swims beneath a slick of plastic debris. Indian Ocean off Sri Lanka. Highly commended in the Environmental Report section, Montphoto competition 2019

Sue Daly / Barrel jellyfish (Rhizostoma octopus) swimming past, Sark, British Channel Islands, UK, September.

Ingo Arndt / Mastigias jellyfish (Mastigias sp) with mass of jellyfish in background, Jellyfish lake, Palau, Western Pacific Islands, Micronesia

Ingo Arndt / Mass of Mastigias jellyfish (Mastigias sp) in Jellyfish lake, Palau, Western Pacific Islands, Micronesia, March 2009

Alex Mustard / Lion's mane jellyfish (Cyanea capillata) with feeding tentacles spread swimming in the sun in shallow water. Gulen, Norway. North East Atlantic Ocean.

Alex Mustard / Aggregation of Golden jellyfish (Mastigias sp.) in a marine lake in Palau, the golden colour of this species comes from symbiotic algae in its tissues. Jellyfish Lake, Eil Malk island, Rock Islands, P...

Luis Quinta / Moon jellyfish (Aurelia aurita) near the surface, Santa Maria Island, Azores, September.