Norbert Wu / Orange Tube Coral (Tubastraea aurea) polyps extended only at night, Dutch Antilles, Caribbean

Fred Bavendam / Fusilier (Caesio sp) school streaming over a vast field of Disc Coral (Turbinaria reniformis), Manado, Sulawesi, Indonesia

Alex Mustard / Yellow cabbage coral (Turbinaria reniformis) growing on a coral reef, surrounded by scalefin anthias: Pseudanthias squamipinnis. Ras Mohammed National Park, Sinai, Egypt. Red Sea

Alex Mustard / Large green branching coral (Tubastrea sp.) with damselfish on a coral reef. Misool, Raja Ampat, West Papua, Indonesia. Misool Marine Protected Area. Ceram Sea. Tropical West Pacific Ocean.

Gary Bell/ Oceanwide / Disc Coral (Turbinaria reniformis) and Banana Fusilier (Pterocaesio pisang) school, Great Barrier Reef, Australia

Pascal Kobeh / Scleractinia / Orange hard coral (Dendrophyllia ramea) with a diver in the background, Canary Islands

Magnus Lundgren / Wild Wonders of China / Yellow tube coral (Tubastrea faulkneri) with the polyps open, Ninepin Group or Kwo Chau Islands, Hong Kong, China.

Magnus Lundgren / Wild Wonders of China / Sun / Tube coral (Tubastraea sp) with tentacles extended to catch zooplankton. Gulf of Bohai, Yellow Sea. Penglai / Dengzhou / Tengchow, Yantai, Shandong Province, China.

Magnus Lundgren / Wild Wonders of China / Sun / Tube coral (Tubastraea sp) with tentacles extended to catch zooplankton. Gulf of Bohai, Yellow Sea. Penglai / Dengzhou / Tengchow, Yantai, Shandong Province, China.

Linda Pitkin / Orange cup coral (Tubastraea sp.), and soft corals, Triton Bay, near Kaimana, West Papua, Indonesia

Linda Pitkin / Orange cup corals (Tubastraea sp.), Triton Bay, near Kaimana, West Papua, Indonesia

David Fleetham / Colony of Green tube coral (Tubastraea micranthus) feeding at night, Fiji Islands.

David Fleetham / Lettuce coral (Turbinaria sp) in reef, Fiji.

Alex Mustard / Yellow wentletrap snail (Epitonium sp.) feeding on Cup coral (Tubastraea sp.). Snail laying clutch of eggs. Nusa Kode, Rinca Island, Komodo National Park, Indonesia. South East Asia. Horseshoe Bay, Sa...

Linda Pitkin / Coral reef with Anthias fish (Pseudanthias squamipinnis) and Twotone chromis (Chromis dimidiata) around Yellow scroll coral (Lettuce coral) (Turbinaria reniformis). With diver Jackson Reef, Straits...

Linda Pitkin / Coral reef with Anthias fish (Pseudanthias squamipinnis) and Twotone chromis (Chromis dimidiata) around Yellow scroll coral (Lettuce coral) (Turbinaria reniformis) Jackson Reef, Straits of Tiran, R...

Norbert Wu / Disc Coral (Turbinaria reniformis) reef, Papua New Guinea

Franco Banfi / Polyp of coral (Tubastraea faulkneri) Tubbataha Natural Park, Sulu Sea, Cagayancillo, Palawan, Philippines

Franco Banfi / Orange cup coral (Tubastrea coccinea) Malpelo Island National Park, UNESCO World Heritage Site, Colombia, East Pacific Ocean

Franco Banfi / Polyp of Orange cup coral (Tubastrea coccinea) Malpelo Island National Park, UNESCO World Heritage Site, Colombia, East Pacific Ocean

Sue Daly / Colony of Sunset cup corals (Leptopsammia pruvoti), Sark, British Channel Islands, UK, July.

Sue Daly / Close-up of a Sunset cup coral (Leptopsammia pruvoti), with tentacles moving, Sark, British Channel Islands, UK, July.

Sue Daly / Colony of Sunset cup corals (Leptopsammia pruvoti), Sark, British Channel Islands, UK, July.

Tony Wu / Cabbage coral (Turbinaria reniformis) surrounded by basslets, damsels and other tropical reef fish, Normanby Island in Milne Bay, Papua New Guinea

Pascal Kobeh / A coral drop off with soft corals (Dendronephthya sp), seafans or gorgonians (Semperina sp) and a hard coral green cup coral (Tubastrea micrantha) Palau, Philippine Sea

Georgette Douwma / Ribbon sweetlips (Plectorhinchus polytaenia) on cleaning station in (Turbinaria sp) coral, Raja Ampat, West Papua, Indonesia.

Georgette Douwma / Black tree coral (Tubastrea micranthus) and Dendrophylliida growing on a large granite boulder. Andaman Sea, Thailand.

Georgette Douwma / Black Tree Coral (Tubastrea micranthus), Dendrophylliida growing on a large granite boulder. Andaman Sea, Thailand.

Pascal Kobeh / Plastic bag hung on a branch of hard corals green cup corals (Tubastrea micrantha). Plastic bags such as this can easily be mistaken for jellyfish by turtles. Mafia Island, Tanzania, Indian Ocean.

Juergen Freund / Cabbage corals (Turbinaria reniformis) with diver in background, Buyat Bay, North Sulawesi, Indonesia. October 2009.

Pascal Kobeh / Close-up of the polyps out of a coral tree (Tubastraea coccinea) at night, Baja California peninsula, Mexico. Sea of Cortez.

Pete Oxford / Black Sun Coral (Tubastraea micranthus) and Sea Goldie (Pseudanthias squamipinnis) school, Fiji

Sue Daly / Sunset cup coral (Leptopsammia pruvoti) Guillaumesse, Sark, British Channel Islands.

Solvin Zankl / Star coral (Astroides calycularis) Raja Ampat, West Papua, Indonesia, Pacific Ocean.

Franco Banfi / Scuba diver and wall covered with sponges and warm water coral (Astroides calycularis) Ponza Island, Italy, Tyrrhenian Sea, Mediterranean

GEORGETTE DOUWMA / Black Tree Coral (Tubastrea micranthus), Dendrophylliidae, with Klein's Butterflyfish (Chaetodon kleinii). Indonesia, October.

GEORGETTE DOUWMA / Black Tree Coral (Tubastrea micranthus), Dendrophylliidae. Indonesia, October.

Jeff Rotman / Arborescent Tubastrea coral (Tubastrea micrantha) Red Sea, Egypt

Chris Newbert / Sea Fan (Melithaea sp) group on Disc Coral (Turbinaria reniformis), Indonesia

Chris Newbert / Soft Coral (Dendronephthya sp) and Soft Coral (Tubastraea sp) reef scenic with schooling fish, Indonesia

Chris Newbert / Bowl Coral (Turbinaria peltata), Indonesia

Flip Nicklin / Orange Cup Coral (Tubastraea coccinea) with feeding tentacles extended at night, Cocos Island, Costa Rica

Fred Bavendam / Disc Coral (Turbinaria reniformis) most exhibiting partial or total bleaching, Kimbe Bay, Papua New Guinea

Chris Newbert / Orange Cup Coral (Tubastraea coccinea), Kona, Hawaii

Chris Newbert / Cabbage Coral (Turbinaria sp) underwater, Papua New Guinea

Birgitte Wilms / Disc Coral (Turbinaria reniformis) garden, 30 feet deep, Papua New Guinea

Norbert Wu / Disc Coral (Turbinaria reniformis) provides shelter for squirrelfish, Ulong Channel, Palau

Fred Bavendam / Sea Star (Leiaster sp) crawling among Stony Coral (Tubastraea sp) on a reef wall, Manado, North Sulawesi, Indonesia

Fred Bavendam / Soft Coral (Ctenocella sp) colony growing amidst large plates of Cabbage Coral (Turbinaria sp), Kimbe Bay, Papua New Guinea

Fred Bavendam / Cabbage Coral (Turbinaria sp) and Stony Coral (Acropora sp) with fish in reef, Papua New Guinea

Fred Bavendam / Soft Coral (Ctenocella sp) colony growing amidst large plates of Cabbage Coral (Turbinaria sp), Kimbe Bay, Papua New Guinea

Fred Bavendam / Orange-spotted Filefish (Cantherhines pullus) sleeping at night among Sponges and Orange Cup Corals (Tubastraea coccinea), Bonaire, Caribbean

Fred Bavendam / Orange-spotted Filefish (Cantherhines pullus) sleeping at night among Sponges and Orange Cup Corals (Tubastraea coccinea), Bonaire, Caribbean

Gary Bell/ Oceanwide / Coral (Tubastrea micrantha) polyps, Great Barrier Reef, Australia

Gary Bell/ Oceanwide / Stony Coral (Tubastraea sp) polyp, Anilao, Philippines

Gary Bell/ Oceanwide / Stony Coral (Tubastraea sp) polyps, Anilao, Philippines

Gary Bell/ Oceanwide / Stony Coral (Tubastraea sp) polyps, Anilao, Philippines

Gary Bell/ Oceanwide / Stony Coral (Tubastraea sp) polyps, Anilao, Philippines

Gary Bell/ Oceanwide / Coral (Tubastrea faulkneri) polyps with fish prey, Great Barrier Reef, Australia

Norbert Wu / Yellowstripe Anthias (Pseudanthias tuka) school in Disc Coral (Turbinaria reniformis) reef, Papua New Guinea

Norbert Wu / Disc Coral (Turbinaria reniformis) reef, Papua New Guinea

Norbert Wu / Disc Coral (Turbinaria reniformis) reef, Papua New Guinea

Pete Oxford / Sun Coral (Tubastrea sp) group, Raja Ampat Islands, Indonesia

Pete Oxford / Cabbage Coral (Turbinaria sp), Raja Ampat Islands, Indonesia

Georgette Douwma / Orange cup coral (Tubastrea sp.) Cebu, Malapascua, Philippines, September

Alex Mustard / Coral grouper (Cephalopholis miniata) resting in its green coral (Tubastraea sp.) home, Raja Ampat, West Papua, Ceram Sea, Pacific Ocean.

David Fleetham / Orange cup coral (Tubastraea coccinea) polyps on coral reef, Hawaii, Pacific Ocean.

Sergio Hanquet / Stony cup coral (Dendrophyllia sp.) surrounded by various reef fish on coral reef, Ari Atoll, Maldives, Indian Ocean.

Franco Banfi / Orange cup coral (Tubastraea coccinea) and Sea fans (Muricea appressa) covering rock face, Espiritu Santo Island, Baja California, Mexico, Sea of Cortez.

Joel Sartore / Photo Ark / Disc coral (Duncanopsammia peltata) on white background, Fort Wayne Children's Zoo.

Joel Sartore / Photo Ark / Disc coral (Duncanopsammia peltata) on black background, Fort Wayne Children's Zoo.

David Fleetham / Substantial colony of Lettuce coral (Turbinaria sp.) forming large section of reef in shallow waters, using as much sunlight as possible and maximizing polyp growth. Diver and fish visible in backgrou...

Franco Banfi / Star coral (Astroides calycularis) covering a rock, Capri Island, Italy, Tyrrhenian Sea.

Franco Banfi / Star coral (Astroides calycularis) covering a rock, Capri Island, Italy, Tyrrhenian Sea.

Franco Banfi / Scuba diver looking at a mass of Star coral (Astroides calycularis) covering a rock, Marine Protected area Punta Campanella, Massa Lubrense, Italy, Tyrrhenian Sea.

David Fleetham / Spherical colony of Lettuce coral (Turbinaria reniformis) on seabed, Fiji, Pacific Ocean.

Noemie Stroh / Yellow scroll coral (Turbinaria reniformis) surrounded by colourful reef fish, Jackson Reef, Red Sea, Egypt, September.

Magnus Lundgren / Sun coral (Tubastraea sp,) opening up after dark to feed at night, Triton Bay, West Papua, Indonesia, Pacific Ocean.

Claudio Contreras / Cortez damselfish (Stegastes rectifraenum), Mexican Hogfish (Bodianus diplotaenia) juvenile and Orange Cup Coral (Sea of Cortez), Mexico, August

Claudio Contreras / Gorgonian and orange cup coral (Tubastraea coccinea) inside cave, San Diego Island, Islands of the Gulf of California Protected Area, Gulf of California (Sea of Cortez), Mexico, September

Claudio Contreras / Pacific mutton hamlet (Alphestes immaculatus) and Orange Cup Coral (Tubastraea coccinea), San Diego Island, Islands of the Gulf of California Protected Area, Gulf of California

Sergio Hanquet / Orange coral (Dendrophyllia Ramea), Tenerife, Canary Islands.

Sergio Hanquet / Orange coral (Dendrophyllia Ramea) and Red sea fan (Leptogorgia ruberrima), La Gomera, Canary islands.

Sergio Hanquet / Orange coral (Dendrophyllia Ramea), Tenerife, Canary Islands.

Pascal Kobeh / Coral formation with invertebrates and among them feather stars / crinoids and Green cup corals (Tubastrea micrantha) Indonesia, Sea of Flores.

David Fleetham / Dead colony of Orange cup coral (Tubastraea coccinea), only the white calcareous skeleton remaining, possibly predated on by nudibranch (Phestilla melanobrachia), Hawaii.

Franco Banfi / Coral (Astroides calycularis) Punta Campanella Marine Protected Area, Costa Amalfitana, Italy, Tyrrhenian Sea, Mediterranean.

Franco Banfi / Yellow cave coral (Leptopsammia pruvoti), Ponza island, Italy, Tyrrhenian Sea, Mediterranean.

David Fleetham / Orange cup coral (Tubastraea coccinea) close up, Philippines.

Shane Gross / A Giant clam (Tridacna gigas) surrounded by Lettuce coral (Turbinaria reniformis), Kosrae, Micronesia.