The Ocean's Most Bizarre Creatures Hiding in Plain Sight

The north coast of Papua New Guinea. One island with two Edens. One rarely seen, yet teeming with life. It holds the planet's greatest diversity of corals and fish. The fearless, the graceful, and the bizarre all call the reef home. This undersea paradise belies its true nature. It's a battleground and adaptability is the key to survival. Beneath these waters teems one of the world's highest concentrations of life. Slightly larger than Texas, Papua New Guinea almost touches the northern part of Australia. At Papua's eastern tip, Milne Bay, with more than 400 species of coral and 1,000 species of fish. Of all the world's coral reefs, Milne Bay is the jewel in the crown. Colorful scenes like this are disappearing. Over the last 30 years, one-fourth of the world's coral reefs have died off, destroyed by warming oceans, human contact, and pollution. So far, Milne Bay remains healthy. Among the most recognizable inhabitants, anemone clownfish. They're immune to the toxic sting of the anemone they live in. Clownfish constantly fend off intruders, like the spotted damselfish, also resistant to the anemone's sting. These yellow and purple fish are anthias. They're different species, but they live side by side. Anthias males spend much of their time tending harems of up to 20 females. Running a harem with no walls seems impossible. But the fish never stray far from home. And no wonder, the reef's top predator is aptly named the silvertip reef shark, which glides in unannounced. Barracudas have sharp eyes and appetites to match. Worse, they often hunt in schools. The wingspan of up to 20 feet, the manta ray is one of the largest predators in the sea. Big though it is, its food is tiny. Like whales, it feeds on plankton. The waters here are rich with food. These mobula rays just seem to be out for a swim. But look closer. The tiny floating particles are one of the greatest sources of food in the sea. Most plankton range in size from less than a millimeter to an inch, but they drift in swarms by the billions. Mobulas feed by swimming open-mouthed through thick layers of plankton. Jellies are enjoying the same meal, but they capture it in a different way. Armed with stinging tentacles, they rake the water, paralyzing plankton with neurotoxin. The tentacles carry the plankton into the jelly's digestive cavity. Like fighter pilots, long-jawed mackerel descend on plankton from every direction, homing the sea until they're full. This strange creature inspired a famous fictional submarine, the Nautilus, from Jules Verne's 20,000 Leagues Under the Sea. The Nautilus can descend by adjusting gas in its 30 internal chambers. Its wafer-thin shell can withstand pressure at more than 2,000 feet, similar to nuclear submarines. Its distant relative, the octopus, prefers the rocky shallows. This feigned octopus is seeking a mate. When he finds one, he's all business. In a massed tangle of arms and hidden to our eyes, he gently transfers a packet of sperm to the female, which he stores for later use. After mating, the male needs an energy boost. With three hearts constantly pumping, the octopus must refuel often. He'll eat just about anything, from crabs to fish. He uses a hidden beak to bore through the shells of clams and snails. Right now, he's searching for mollusks, worms, and shrimp. This octopus has trapped fish against the coral and moves prey into its mouth with dozens of powerful suction cups. If the coral is small enough, the octopus can engulf the entire thing, eating all that's hiding inside. This strategy is highly effective. Nothing seems to slow it down. Parents bump and bite as their young are captured. It can feed and fend off attackers at the same time. After shaking up the neighborhood, the octopus retires to its den. Residents use special tactics to avoid predators like the octopus. The peacock flounder uses camouflage as its defense. This fingered dragonet also keeps a low profile. Others, like the flatworm, have nothing to hide. They're filled with deadly toxins. Some just get creative, like this crab. It dangles a leaf over its body to appear like a piece of sinking foliage. Another crab guards itself by attaching stinging anemones. Some costumes are down and dirty. And while some crabs disguise themselves as plants, other life mimics crabs. The spots on these gobies look like a crab's eyes. The better to scare off predators. The harmless snake blennyfish poses as a venomous banded sea snake. Sea urchins don't require a costume. They are the porcupines of the ocean. Cardinal fish have learned to hide among the urchin's venomous needles. The lionfish on the top right must wait for the fish to leave their haven. But they're not going anywhere. In a habitat with few hiding places, the pipefish is a master of camouflage. Imitation is the height of flattery and safety. The two pipefish on the right are dead ringers for the halimeda plant. To avoid predators, pipefish keep still. They can mimic leaves, seagrasses, and even animals. Pipefish are weak swimmers in open water and prefer the safety of coral reefs and seagrass beds. Seahorses are closely related to pipefish. They both have tube-like mouths. Most seahorses are just a few inches in size. But the pygmy seahorse is smaller than a human fingernail. It's so small, the species wasn't discovered until the 1960s. Dragon seamoths are cousins of pipefish and seahorses. Commonly found in pairs, the male and female stroll in search of food. They vacuum small creatures like worms from their burrows. Like the dragon seamoth, the frogfish hunts on the seafloor. It looks more like a sponge than a predator. They're almost impossible to detect unless they're moving. A superb ambush predator, it has the fastest strike of any fish. At one six-thousandth of a second, it's too fast even for slow-mo. Like the frogfish, the scorpionfish and stonefish hunt so well from ambush, they seldom need to swim. Another non-swimmer, the nudibranch, more commonly known as the sea slug. The nickname doesn't suit these beautiful creatures. Blind and bisexual, they avoid predators by displaying colors that scream toxic. This bizarre sea slug survives by using the sun to grow algae in its own skin. This alien-looking nudibranch uses its bubble head like a fishing net. to trap small particles of food. The tigress is a carnivore that consumes prey whole. In this case, it's another nudibranch. The tigress's small teeth keep the victim from escaping. Then the prey is slowly digested. Some nudibranchs are pushovers. This sea slug carries freeloading passengers, imperial shrimp. The slug delivers them to food-rich areas. The shrimp hitch rides on other species. This sea cucumber has inherited the duet. As the cucumber forages, the shrimp scoop up delicacies from the reef. Some imperials will ride just about anything. Not all shrimp are freeloaders. Some offer a service to other creatures, free of charge. This isolated coral mound is a prime example of a cleaning station. Here, the normal tension between creatures relaxes. Shrimp descend on a moray eel that displays a calm disposition. Cleaner shrimp remove parasites, debris, and infected tissue. In return, they get an easy meal. It's called symbiosis, two species that scratch each other's back. For now, the moray tolerates the shrimp's attention. Another classic example of a mutually beneficial relationship is between this fellow, the goby, and his buddy, a blind shrimp. The shrimp digs a burrow and keeps it clear. In the process, he gives the goby a place to lay its eggs. In return, the goby watches out for predators. Both share the burrow. Some lucky gobies have two excavators working for them. A predator the goby watches for, the mimic octopus. This escape artist uses mimicry and camouflage to avoid sharks, dolphins, and eels. Tapus use all eight arms to probe for mollusks and crustaceans. For its finale, its own disappearing act. With so many predators around, parents take care where they hide their eggs. A squid lays her eggs among palm fronds near shore. Her mate keeps watch for predators. Using a glue-like substance, she may place up to a thousand eggs here. In two months, they'll hatch. Nearby, another egg-laying performance is about to begin. Cuttlefish belong to the same family as octopus, nautilus, and squid. Males use complex posturing and color displays to protect nests from rivals. This female isn't feeding on stinging-fire coral. She's laying eggs. Carefully, she glues each egg inside the coral's branches. The eggs are safe from most predators. These intelligent creatures hatch, mate, and die in about one year. In 40 days, a new generation will repopulate the reef. For some species, safety lies in sheer numbers. Baitfish have nowhere to hide, so they school. They gamble, hoping a predator will get someone else. Millions blacken the water near sundown before night darkens the sea itself. Vast, yet vulnerable, just like the reef. As the planet's waters warm, this Eden is only a few degrees away from disappearing. But for now, Eden and its residents go on.