Aflo / Northern sea nettle (Chrysaora Melanaster) floating, with Mackerel fry ( Carangidae) Izu, Japan. January.

Claudio Contreras,Claudio Contreras / Jellyfish, Inanuran Island, Danajon Bank, Central Visayas, Philippines, April

Ashley Cooper / Lions mane jellyfish (Cyanea capillata) washed ashore on a Northumberland Beach, England, UK. July 2014

Ashley Cooper / Girl looking at Lions mane jellyfish (Cyanea capillata), washed ashore on a Nothumberland Beach, England, UK. July 2014

Sylvain Cordier / Japanese Sea nettle or North Pacific Sea Nettle (Chrysaora melanaster), Monterey aquarium, USA

Sylvain Cordier / Japanese Sea nettle or North Pacific Sea Nettle jellyfish (Chrysaora melanaster) Monterey Aquarium, USA

Aflo / Northern sea nettle (Chrysaora melanaster) with extremely long tentacles, Izu, Japan.

David Fleetham / Brown jellyfish (Chrysaora melanaster), California, USA.

Lewis Jefferies / Crystal jellyfish (Aequorea victoria) floating above Golden Kelp forest (Laminaria ochroleuca) Lundy Island, Bristol Channel, Devon, UK.

Lewis Jefferies / Grey seal (Halichoerus grypus) swimming over Thongweed (Himanthalia elongata) with Moon jellyfish (Aurelia aurita) in background, Lundy Island, Bristol Channel, Devon, UK.

Russell Laman / Pacific sea nettle (Chrysaora fuscescens) floating among Giant kelp (Macrocystis pyrifera) in the murky waters off Monterey, California, USA, Pacific Ocean.

Alex Mustard / Crystal jellyfish (Aequorea sp.) floating above a forest of Kelp (Laminaria hyperborea), Island of Coll, Inner Hebrides, Scotland, UK, Atlantic Ocean.

Alex Mustard / Blue lion's mane jellyfish (Cyanea lamarckii) drifting through a seaweed forest with Red pom-pom seaweed (Ceramium sp.) and Spaghetti seaweed (Himanthalia elongata), Island of Coll, Inner Hebride...

Alex Mustard / Crystal jellyfish (Aequorea sp.) floating above a forest of Kelp (Laminaria hyperborea), Island of Coll, Inner Hebrides, Scotland, UK, Atlantic Ocean.

Alex Mustard / Dense growth of Bootlace seaweed (Chorda filum) in shallow water, with a Stalked jellyfish (Calvadosia sp). clinging on between strands, Kimmeridge, Dorset, England, UK, English Channel. July.

Alex Mustard / Small Stalked jellyfish (Calvadosia sp.) attached to Bootlace weed / Mermaid's hair (Chorda filum), Pendennis Head, Cornwall, UK. English Channel.

David Hall / Split level of a Lion's mane Jellyfish (Cyanea capillata) and Feather-boa kelp (Egregia menziesii), Seven-tree Island, Browning Pass, Queen Charlotte Strait, British Columbia, Canada. September.

David Hall / Lion's mane jellyfish (Cyanea capillata) and Bull kelp (Nereocystis luetkeana) Hunt Rock, Queen Charlotte Strait, British Columbia. October.

Magnus Lundgren / Brown paper nautilus (Argonauta hians) female riding on a jellyfish, off Anilao, Balayan Bay, Batangas, Philippines.

Magnus Lundgren / Brown paper nautilus (Argonauta hians) male riding on a jellyfish, off Anilao, Balayan Bay, Batangas, Philippines.

Magnus Lundgren / Brown paper nautilus (Argonauta hians) female riding on a jellyfish, off Anilao, Balayan Bay, Batangas, Philippines.

Magnus Lundgren / Brown paper nautilus (Argonauta hians) female riding on a jellyfish, off Anilao, Balayan Bay, Batangas, Philippines. .

Magnus Lundgren / Brown paper nautilus (Argonauta hians) surfing on a jellyfish, Balayan Bay, Luzon, Philippines. The nautilus uses its jellyfish host both as a food source, and as a defensive weapon. Photographed at n...

Magnus Lundgren / Brown paper nautilus (Argonauta hians) surfing on a jellyfish, Balayan Bay, Luzon, Philippines. The nautilus uses its jellyfish host both as a food source, and as a defensive weapon. Photographed at n...