Pete Oxford / Broadleaf Gulfweed (Sargassum fluitans) floating mat, Ambergris Caye, Belize

Solvin Zankl / Tiny crab on Broad-toothed Gulfweed (Sargassum fluitans) Sargassum Community. Sargasso Sea, Bermuda

Juergen Freund / Sargassum seaweed (Sargassum sp) floating on the sea surface, Palawan, Philippines, May

Norbert Wu / Atlantic Spotted Dolphin (Stenella frontalis) playing with Sargassum weed, Little Bahama Bank, Caribbean

Alex Mustard / A raft of sargasso weed (Sargassum natans) in open ocean. Off shore, Grand Cayman, Cayman Islands, British West Indies. Caribbean Sea.

Sergio Hanquet / Gulfweed crab (Planes minutus), epibiont on Loggerhead turtle (Caretta caretta). Tenerife, Canary Islands.

Tony Wu / Korean sandlance (Hypoptychus dybowskii) egg clusters on Sargassum (Sargassum horneri). Fish produce sticky secretion in kidneys that adheres eggs to Sargassum. Hokkaido, Japan. May.

Nick Upton / Japanese wireweed (Sargassum muticum), invasive non-native species in Atlantic Ocean. Cornwall, England, UK. September.

Nick Upton / Japanese wireweed (Sargassum muticum), invasive non-native species in Atlantic Ocean. Cornwall, England, UK. September.

Nick Upton / Japanese wireweed (Sargassum muticum), invasive non-native species in Atlantic Ocean. Cornwall, England, UK. September.

David Fleetham / Sargassum fish (Histrio histrio) at the sea surface with floating sargassum weed. Hawaii.

Robin Chittenden / Japanese Wireweed (Sargassum muticum) in rock pool, Isle of Wight, Hampshire, UK August