Alex Mustard / Grooved brain coral (Diploria labyrinthiformis) at night with polyps extended to feed, Grand Cayman, Cayman Islands, British West Indies. Caribbean Sea.

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.

David Shale / Hydromedusa/ Trachymedusa (Crossota sp) from approx 2700m, mid Atlantic ridge, June 2010

Michele Westmorland / Snorkeler swimming with harmless Jellyfish (Mastigias papua etpisonii), Jellyfish Lake, Rock Islands, Palau, Micronesia.

Alex Mustard / Synchronous spawning of a mountainous star coral (Montastraea faveolata) at night. East End, Grand Cayman, Cayman Islands, British West Indies, Caribbean Sea.

Linda Pitkin / 2020VISION / Pink sea fan / Warty coral (Eunicella verrucosa) with attached eggs of a Common squid (Loligo vulgaris), eggcase of a Lesser-spotted dogfish (Scyliorhinus canicula), and Spiny starfish (Marthasterias...

Linda Pitkin / 2020VISION / Sunset cup coral / Yellow cave coral (Leptopsammia pruvoti), on sponge covered rock face, Lundy Island Marine Conservation Zone, Devon, England, UK, May

Alex Mustard / Boulder star coral (Montastraea annularis) spawning at night with released bundles of eggs and sperm floating away in the water column, East End, Grand Cayman, Cayman Islands, British West Indies, Car...

Alex Mustard / A large colony of Mountainous star coral (Montastraea faveolata) spawning at night on a coral reef, showing the synchronous release of bundles of eggs and sperm, East End, Grand Cayman, Cayman Islands...

Floris van Breugel / Staghorn corals (Acropora) on the coast of tropical island Ofu, one of the Manu'a islands, American Samoa. 2012.

Floris van Breugel / Tiny thimble jellyfish (Linuche unguiculata) drift with the current in the calm turquiose waters of a lagoon in Ofu, American Samoa. The window of sky is called Snell's Window, caused by refraction of...

Graham Eaton / Compass Jellyfish, in murky water, Abersoch, Cardigan Bay, Wales, July

Alex Mustard / 2020VISION / Amphipod (Iphimedia obesa) on top of a colony of Deadman's fingers (Alcyonium digitatum) coral, Loch Carron, Ross and Cromarty, Scotland, UK, April. Highly commended in the British Wildlife Photograph...

Alex Mustard / 2020VISION / Great spider crab (Hyas araneus) on Deadman's fingers (Alcyonium digitatum) coral, feeding in a current, Loch Carron, Ross and Cromarty, Scotland, UK, April

Graham Eaton / Common / Moon Jellyfish (Aurelia aurita) seen from below. Cardigan Bay, Wales, June. Highly commended, marine category, British Wildlife Photography Awards (BWPA) competition 2012.

Solvin Zankl / GEOMAR / Polar shrimp (Lebbeus polaris) on live Lophelia (Lophelia pertusa) from Trondheimfjord, North Atlantic Ocean, Norway. Controlled conditions. Photo taken in cooperation with GEOMAR coldwater coral res...

Nick Upton / Split level view of a Beadlet anemone (Actinia equina) attached to a boulder encrusted with Maerl (Lithothamnion glaciale) a red coralline alga, in a large rockpool, Crail, Scotland, UK, July

David Shale / Solenosmilia sp and eunicid polychaete and bamboo coral. Collected from coral sea mount near Dragon vent field on SW Indian Ridge, Indian Ocean.

David Shale / Black coral (Antipatharia) with tendrils extruded to catch prey. Collected from coral sea mount near Dragon vent field on SW Indian Ridge, Indian Ocean.

Alex Mustard / Ornate ghost pipefish (Solenostomus paradoxus) young hides amongst the branches of a black coral bush (Antipathes sp) Sangeang Island, Sumbawa, Indonesia, Flores Sea.

Alex Mustard / 2020VISION / Plumose anemones (Metridium senile) feeding on Moon jellyfish (Aurilia aurita), which they have captured. Loch Long, Argyll and Bute, Scotland, UK, June. Did you know? Loch Long was previously used as...

Alex Mustard / 2020VISION / Devonshire cup coral (Caryophyllia smithii) photographed under deep blue light to reveal its fluorescent pigments, showing up as green in this photo. Plymouth Sound, Devon, UK, English Channel, July

Alex Mustard / 2020VISION / Detail of Plumose anemone (Metridium senile) in its retracted state at slack water when it is not feeding. Plymouth Sound, Devon, England, UK, English Channel, July

Alex Mustard / Brain coral (Pseudodiploria strigosa) photographed under blue light to excite the fluorescence, Little Cayman, Cayman Islands, British West Indies, Caribbean Sea.

Alex Mustard / A diver exploring a coral reef with formation of brown tube sponges (Agelas conifera) red rope sponges (Amphimedon compressa) and deepwater sea fans (Iciligorgia nodulifera) East End, Grand Cayman, Ca...

Alex Mustard / Secretary blenny (Acanthemblemaria maria) making a home in a deserved worm tube of a great star coral (Montastraea cavernosa), East End, Grand Cayman, Cayman Islands, British West Indies, Caribbean Se...

Pete Oxford / Upside down Jellyfish (Cassiopeia sp) Jardines de la Reina National Park, Cuba, Caribbean

Linda Pitkin / 2020VISION / Dead man's fingers (Alcyonium digitatum), growing on rock faces below the kelp, St Abbs (St Abbs and Eyemouth Voluntary Marine Reserve), Berwickshire, Scotland, UK, October 2011. Did you know? Soft co...

Linda Pitkin / 2020VISION / Close-up of Dahlia anemone (Urticina felina / Tealia felina, St Abbs (St Abbs and Eyemouth Voluntary Marine Reserve), Berwickshire, Scotland, August 2011

Linda Pitkin / 2020VISION / Dahlia anemone (Urticina felina / Tealia felina), on bed of Common brittlestars (Ophiothrix fragilis), St Abbs (St Abbs and Eyemouth Voluntary Marine Reserve), Berwickshire, Scotland, August 2011

Doug Perrine / Flower Hat Jelly / Jellyfish (Olindias formosa), a rare hydromedusa with fluorescent tentacle tips. Endemic to Brazil, Argentina, and southern Japan.

Roberto Rinaldi / Yellow fan coral / Seafan (Paramuricea clavata) amongst mass of invasive algae (Caulerpa taxifolia) with Rainbow wrasse fish (Coris julis), Strait of Messina, Southern Italy

David Shale / Detail of deepsea Sea pen (Pennatulacea) from coral seamount, Indian Ocean, December 2011

David Shale / Deepsea Hermit crab with zoanthid (Epizoanthus sp) on shell, from a coral seamount in the Indian Ocean, November 2011

David Shale / Deepsea Anemone from a coral seamount, Indian ocean, November 2011

Jeff Rotman / Gorgonian Seafan Coral (Gorgonacea) polyps open to feed at night. South China Sea, Sipadan Island, Borneo.

Jeff Rotman / Alcyonarian Coral (Dendronephthya spp.) polyps open and feeding. Red Sea, Egypt.

Alex Mustard / 2020VISION / A gully lined with the soft coral Dead man's fingers (Alcyonium digitatum) growing beneath a summer canopy of kelp, Rosehearty, Moray Firth, Scotland, UK, June

Alex Mustard / 2020VISION / Colourful deadman's fingers (Alcyonium digitatum) a type of soft coral, growing on a wall in Conservation Bay, Loch Carron, Scotland, UK, April. Model released.

Alex Mustard / 2020VISION / Group of orange and white Plumose anemones (Metridium senile) with Moon jellyfish (Aurilia aurita) overhead in a sealoch, Loch Long, Argyll and Bute, Scotland, UK, June

Alex Mustard / 2020VISION / Phosphorescent Seapen (Pennatula phosphorea) extends out of the muddy seabed in the calm waters of the upper reaches of a Scottish sea loch. Loch Duich, Ross and Cromarty, Scotland, UK, April

Alex Mustard / 2020VISION / Compass jellyfish (Chrysaora hysoscella) swimming over a rocky reef, Plymouth, Devon, UK, August. Did you know? Compass jellyfish change gender throughout their lives, starting off male, and later bec...

Alex Mustard / 2020VISION / Group of Jewel anemones (Corynactis viridis) photographed under blue light to show their fluorescence, Plymouth Sound, Devon, UK, July

Georgette Douwma / Bubble Tip Anemone (Entacmaea quadricolor). The tentacles are usually a dull brown, but this anemone is partially bleached and has lost most of the endosymbiotic zooxanthellae. Raja Ampat, West Papua,...

Doug Perrine / Swarm / aggregation of venomous Moon jellyfish (Aurelia aurita) Port Fidalgo, Prince William Sound, USA, July

Georgette Douwma / Leather Coral (Sinularia flexibilis). Komodo National Park, Indonesia.

Georgette Douwma / Soft Coral (Dendronephthya sp) with Blueline snappers (Lutjanus kasmira). Rinca, Komodo National Park, Indonesia.

Juergen Freund / Tiny reef crab on soft coral, West New Britain, Papua New Guinea.

Juergen Freund / Gorgonian fan coral with Featherstar / crinoid attached, West New Britain, Papua New Guinea.

Juergen Freund / Orange cup coral (Tubastrea faulkneri) with polyps open, Batangas, Philippines.

Juergen Freund / Orange cup coral (Tubastrea faulkneri) detail of mouth and tentacles, Batangas, Philippines.

Juergen Freund / Gorgonian fan coral with crinoids / featherstars, Kimbe Bay, West New Britain, Papua New Guinea

Juergen Freund / View of sea surface through a Whip coral forest (Junceella sp) Kimbe Bay, West New Britain, Papua New Guinea

Juergen Freund / Details of mouth of an anemone, Kimbe Bay, West New Britain, Papua New Guinea.

Juergen Freund / Soft coral (Alcyonacea) in the shallow mangroves with diver, split level. North Raja Ampat, West Papua, Indonesia, February 2010

Juergen Freund / Bean shaped polyps of an Anchor coral (Euphyllia ancora), a large polyp stony (LPS) coral. Misool, Raja Ampat, West Papua, Indonesia.

Juergen Freund / Fan coral (Gorgonacea) with open polyps. Misool, Raja Ampat, West Papua, Indonesia..

Juergen Freund / Detail of a soft coral (Dendronephthya sp). Misool, Raja Ampat, West Papua, Indonesia

Juergen Freund / Fluorescent corals, Misool, Raja Ampat, West Papua, Indonesia

Juergen Freund / Mushroom leather coral (Sarcophyton sp) Bali, Indo-pacific.

Juergen Freund / Whip coral (Gorgonaceae) Komodo NP, Indonesia

Juergen Freund / Blue soft corals, Lembeh Strait, North Sulawesi, Indonesia.

Juergen Freund / Close up of the polyps of a Flowerpot coral (Goniopora sp.). Lembeh Strait, North Sulawesi, Indonesia.

Juergen Freund / Split-level shot of Fan coral (Gorgonacea) in the shallows with boat shilouetted against the sunset in the background. North Raja Ampat, West Papua, Indonesia, February 2010

Juergen Freund / Colorful coral reef with soft corals (Alcyonacea) and fan corals (Gorgonacea). Misool, Raja Ampat, West Papua, Indonesia, January

Juergen Freund / Fluorescent coral viewed under normal light, Misool, Raja Ampat, West Papua, Indonesia, sequence 1/2

Juergen Freund / Fluorescent coral viewed under UV light, Misool, Raja Ampat, West Papua, Indonesia, sequence 2/2

Suzi Eszterhas / Two Purple / Striped Jellyfish (Pelegia / Chrysaora colorata) Monterey Bay Aquarium, California, USA, Captive

Georgette Douwma / Bleached coral {Acropora sp} caused by loss of algae with living purple polyps. Maldives.

David Shale / Hydromedusa / Trachymedusa (Crossota sp) showing tentacles, from approx 2700m, mid Atlantic ridge, June 2010

David Shale / Hydromedusa / Trachymedusa (Crossota sp) from approx 2700m, mid Atlantic ridge, June 2010

Alex Hyde / Swarm of Common / Moon Jellyfish (Aurelia aurita)in sea loch, Isle of Mull, Scotland. June. Digitally stitched panorama.

Alex Hyde / Swarm of Common / Moon Jellyfish (Aurelia aurita)in sea loch, Isle of Mull, Scotland. June.

Alex Hyde / Common / Moon Jellyfish (Aurelia aurita) close-up, breaking the water's surface, Isle of Mull, Scotland. June.

Alex Hyde / Swarm of Common / Moon Jellyfish (Aurelia aurita) in sea loch, Isle of Mull, Scotland. June.

Graham Eaton / Common / Moon Jellyfish (Aurelia aurita) swarming in shallow water over kelp, Cardigan Bay, Wales, June. Highly commended in Coast and Marine category, British Wildlife Photographer of the Year Awards...

Georgette Douwma / Soft coral (Dendronephthya mucronata) on sandy seabed. Komodo National Park, Indonesia

Georgette Douwma / Spiral wire coral (Cirrhipathes sp) Indonesia

Georgette Douwma / Tree coral (Dendronephthya sp) on sandy sea bed. Rinca, Komodo National Park, Indonesia

Neil Lucas / Sea nettles (Chrysaora quinquecirrha) in aquarium, with crowd of people watching, Atlanta, USA, October 2009

Wild Wonders of Europe / Zankl / Purple stinger / Common jellyfish (Pelagia noctiluca) Malta, Mediteranean, May 2009

Wild Wonders of Europe / Lundgren / Skeleton shrimp (Caprellidea sp) on a hydroid, Saltstraumen, Bod, Norway, October 2008

Wild Wonders of Europe / Lundgren / Plumose sea anemone (Metridium senile) close-up, Saltstraumen, Bodö, Norway, October 2008

Sue Daly / Close up of polyps and tentacles of Sea fan (Gorgonia sp) Cebu, Philippines, March

Wild Wonders of Europe / Lundgren / True jelly fish (Pelagia noctiluca) Pico, Azores, Portugal, June 2009

Wild Wonders of Europe / Lundgren / True jelly fish (Pelagia noctiluca) Pico, Azores, Portugal, June 2009

Wild Wonders of Europe / Lundgren / Portuguese man-of-war (Physalia physalis) on the water surface, Pico, Azores, Portugal, June 2009

Wild Wonders of Europe / Lundgren / Portuguese man of war (Physalia physalis) Pico, Azores, Portugal, June 2009

Wild Wonders of Europe / Sá / Lion's mane jellyfish (Cyanea capillata) Mull, Scotland, June 2009

Wild Wonders of Europe / Sá / Lion's mane jellyfih (Cyanea capillata) with diver photographing it, Mull, Scotland, June 2009

Wild Wonders of Europe / Banfi / Keys simnia (Neosimnia spelta) on a Yellow gorgonia (Eunicella cavolini) Larvotto Marine Reserve, Monaco, Mediterranean Sea, July 2009

David Shale / Medusa caught with 1m ring net between 0 and 150m, Mid-Atlantic Ridge, North Atlantic Ocean

David Shale / Deepsea Medusa jellyfish (Colobonema sp), Mid-Atlantic Ridge, North Atlantic Ocean

Wild Wonders of Europe / Zankl / Golden cup coral (Astroides calycularis) Malta, Mediteranean, May 2009

Wild Wonders of Europe / Zankl / Star coral (Astroides calycularis) Malta, Mediteranean, May 2009

Wild Wonders of Europe / Zankl / Purple stinger / Common jellyfish (Pelagia noctiluca) Malta, Mediteranean, May 2009