From parrotfish that cover themselves in a blanket of their own mucus to tiny pygmy sea horses, there are some bizarre sea creatures that live in coral reefs. In this slideshow you can explore some of the oddest and most amazing ones there are to see. Take a look at corals that can burn, and learn what fish mark a healthy reef.
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Bizarre and Beautiful Coral Reef Animals
Reef Fish, French Frigate Shoals
Credit: James WattHealthy coral reefs support a mindboggling array of life. Here, at Rapture Reef in the Northwestern Hawaiian Islands, colorful fishes throng the waters for as far as the eye can see.
Spotfin Lionfish
Credit: Chuck SavallThe spotfin lionfish (Pterois antennata), with venomous spines extended, is native to Indo-Pacific reefs. Certain lionfish species have invaded reefs in Florida, the Caribbean and are moving up the Atlantic coast. The native Pacific fish probably escaped from an aquarium. Lionfish are aggressive predators and threaten local species. They are also referred to as turkeyfish because depending on how you view the lionfish it can look like the plumage of a turkey.
Parrotfish in Mucus Cocoon
Credit: Lexa GrutterA parrotfish (Chlorurus sordidus) creates a mucus cocoon to protect it from parasites, like bloodsucking isopods, while it sleeps.
Clownfish in their Host Anemone
Credit: Flickr user Jenny Huang (JennyHuang)/EOLTwo bright orange anemonefish (Amphiprion ocellaris) poke their heads between anemone tentacles. Anemonefish are able to swim amongst the stinging tentacles without getting stung — but no one knows exactly sure how. One dominant theory explains that they have a protective slime coating their bodies. However, anemonefish are not born with this protective slime and scientists don't know how they develop it.
Purple Nudibranch
Credit: Jeff DawsonThe feathery strands at the back of this nudibranch’s (Chromodoris willani) body are no mere adornment: they’re its gills! Nudibranchs, shell-less snails or sea slugs, are named for these tufted gills, as "nudibranch" comes from Latin and Greek words meaning "naked gills." They're known for their bright coloration, and this species, found in Western Pacific Ocean coral reefs, ranges from dark purple to bright white.
Green Sea Turtle
Credit: Pedro Carrillo/Nature’s Best PhotographyA diet of algae and seagrasses gives this turtle (Chelonia mydas) greenish colored fat—and its name. Weighing as much as 500 pounds, the threatened green sea turtle lives its life at sea, with only females coming to shore to lay eggs.
Crown of Thorns Starfish
Credit: David Burdick/NOAA Photo LibraryA crown-of-thorns starfish (Acanthaster planci) on a reef in the Marianas Islands. An “outbreak” of these coral-eating starfish can decimate a reef, and they have done great damage on Australia's Great Barrier Reef.
Hawaii’s Maro Coral Reef
Credit: ©James D. Watt/Ocean StockThis bluefin trevally is lucky to call Hawaii’s Maro Coral Reef, part of the Papahānaumokuākea Marine National Monument, its home. Maro is the largest reef in the Northwest Hawaiian Islands and just one of the many marine ecosystems protected in the 140,000 square miles of Papahānaumokuākea, one of the largest marine protected areas in the world.
Eye to Eye With a Pygmy Seahorse
Credit: Critidoc, FlickrA master of disguise, the pygmy seahorse (Hippocampus bargibanti) grows to only 2cm in length and matches the gorgonian coral that it lives on. The pygmy seahorse is so successful at hiding that it was not found until its home was being studied in a lab. So little is known about this mysterious creature that the major threats to it are unknown. However a possible threat is removing the pygmy seahorse from its habitat for aquarium use. Due to this, countries like Australia are being cautious and requiring export permits to protect this shy creature.
Mandarinfish Duo
Credit: Erwin PoliakoffThese beautiful mandarinfish (Synchiropus splendidus) are covered in bright blue, red, yellow and orange waves. What they lack, however, are traditional fish scales. They live in western Pacific tropical coral reef ecosystems and instead of your typical fish scales they are covered in a smelly, thick mucus coating. It's possible that this mucus, which not only smells—but tastes—bad, is used as a deterrent to predators.
Coral Goby Cleans Coral
Credit: Courtesy of Danielle Dixson, Georgia Institute of TechnologyOne of the first signs of a sick coral reef is seaweed creeping across the corals, stealing their precious sunny real estate. Healthy corals, however, aren't completely hopeless: in some reefs, small fishes, such as this broad-barred goby (Gobiodon histrio), help eat the seaweeds away. But how do corals contact the fish to ask for cleaning services? By sending out a chemical signal.
Coral Head Near Pearl and Hermes Atoll
Credit: Louiz RochaA rainbow of tropical fish hovers over a coral head near the Pearl and Hermes Atoll, part of the Papahānaumokuākea World Heritage Site.
Surgeonfish: Indicators of a Healthy Reef
Credit: Michael WebsterConvict surgeonfish (Acanthurus triostegus) are the roaming sheep of the reef but, instead of noshing on grass, they feed on algae. Their grazing helps to balance the growth of algae and coral on the reef. Both corals and algae get their food from sunlight, but there is limited space underwater where sunlight reaches. Corals take much longer to grow, so the seaweed needs to be trimmed by surgeonfish and other herbivores regularly to keep it from growing out of control and blocking the sun from the coral. Seeing many herbivorous fish and not too much algae or seaweed is a sign of a healthy reef. But if herbivores are overfished, there are fewer checks on the seaweed and algae.
Yellow-mouth Moray Eel in the Red Sea (Eilat, Israel)
Credit: Steven Kovacs, Moore Haven, Florida, USA, www.underwaterbliss.com“This moray eel was resting among some hard coral and was mesmerized by my dive lights, making it a very cooperative subject. The moray eel rhythmically opens and closes its mouth to move water through its gills and facilitate respiration, giving it the appearance of being aggressive and making for a dramatic portrait.” -- Nature's Best photographer, Steven Kovacs
A School of Hawaiian Squirrelfish
Credit: James Watt, USFWS PacificCheck out the eyes on these Hawaiian squirrelfish (Sargocentron xantherythrum)! Because squirrelfish are almost entirely nocturnal, they need big eyes to absorb as much moonlight and starlight as they can in the dark. During the day, they hide out in the nooks and crannies of tropical coral reefs. To defend its small hiding place, the squirrelfish grunts by grinding its teeth and stretching the muscles along its gas bladders—grunts that sound a bit like the chatter of squirrels!
Australia's 1.2 Million Mile Marine Reserve
Credit: Tony BrownIn November 2012, Australia began protecting a huge swath of its ocean from overfishing and oil exploration, creating the largest network of marine reserves in the world at a grand total of 1.2 million square miles (3.1 million square kilometers). The area, a third of the continent’s territorial waters, includes an underwater canyon as large as the U.S. Grand Canyon, seagrass meadows, and the biodiverse reefs of the Coral Sea, including the one pictured here at Montague Island.
Can You Spot the Seahorse?
Credit: Sam Taylor / Guylian Seahorses of the World 2005, courtesy of Project SeahorseIt's a pygmy seahorse (Hippocampus bargibanti), found in Indonesia's biodiverse Coral Triangle and one of the smallest seahorse species in the world! They can change colors like a chameleon to blend into their environment. This helps to protect them from predators and ambush their prey.
Fireworm Takes on Fire Coral
Credit: Allen G. Collins/NOAAThis bearded fireworm (Hermodice carunculata) must have a strong stomach -- it’s sucking on fire coral (Millepora sp.), which would give the unlucky snorkeler a nasty sting. Encountered in St. John, U.S. Virgin Islands, the worm in this photo is about 15 cm (6 inches) long, but they can get up to twice that length. Those venom-filled bristles can break off in human skin, causing an intense burning sensation.
Butterflyfish and Wrasse
Credit: © Brian Skerry, www.brianskerry.comA wrought iron butterflyfish, Chaetodon daedalma, being cleaned by a small wrasse in the waters of Japan's Ogasawara Islands.
Toothy Goby in Coral
Credit: Mark Rosenstein, FlickrThe toothy goby or common ghost goby (Pleurosicya mossambica) lives among soft corals and sponges in the Indo-Pacific ocean. The relationship it has with its host is commensal, which means the goby benefits from the protection and habitat in the corals, but the coral doesn't get hurt or benefit from the relationship.
Many of the other 2000 or so species of gobies form such symbiotic relationships, both commensalisms and mutualisms. Gobies and pistol shrimps will live together, with the near-blind shrimp tending their sandy burrow while the goby watches for predators. And cleaner gobies (Elacatinus) clean the mouths of bigger fish that would normally treat them as prey.
Caribbean Reef Shark
Credit: © Brian Skerry, www.brianskerry.comLiving in warm shallow waters often near coral reefs in the Western Atlantic, from Florida to Brazil, the Caribbean reef shark (Carcharhinus perezi) is the most abundant shark in the Caribbean. It feeds mostly on bony fishes and rarely attacks humans. Despite the shark's abundance in some regions, it has a high mortality rate from bycatch and is sought by commercial fisheries for its fins and meat. It is illegal to catch Caribbean reef sharks in U.S. waters. The International Union for the Conservation of Nature (IUCN) lists the species' status as "Near Threatened."
White Xenia Crab from Indonesia
Credit: Marli Wakeling/Nature's Best Photography“Lembeh Strait is a fantastic place to find species that have evolved to resemble other animals or plants to survive. Because of the lens I was using, I had to get really close to this crab. As I moved in, it retreated into the xenia coral polyps. When I backed up, it came back out. The skittish crab, in addition to having the wrong lens for the task, made this a challenging shot.” -- Nature's Best Photographer, Marli Wakeling