In Hawaii's Kona Waters, a moray eel is staring at a colorful fish. If the eel decides to pounce on its prey, it will show two rows of teeth instead of one. The discovery of a second row of teeth in the throat of an eel will hook the prey and make it impossible to break free. This unusual ability allows eels to swallow large animals without opening their mouths, such as in the limited space of the reef caves in which they live. Photographed by Heather Perry
There is no doubt that the great white shark is at the top of the Pacific Rim marine food chain. The world's largest predatory fish can weigh more than 5,000 pounds (2,270 kilograms) and be more than 20 feet (6 meters) long. Great white sharks have about 300 teeth and usually prey on sea lions, seals, small-toothed whales, turtles and carrion. About a third of the more than 100 shark injuries a year are caused by great white sharks, but its attacks are often unintentional and rarely fatal. Photographed by Raul Tozan
The striped spiny seabream lives around coral reefs in the vast waters from the Indian To Pacific Ocean, and its appearance is very ornamental, but humans must be very careful when encountering it, because it has a stinger on its tail. Scientists believe that about 1,200 different species of poisonous fish live in the world's oceans, and it is estimated that about 50,000 injuries occur each year. But fish venom can also bring many benefits, such as being used to develop new drugs. Photograph: Paul Nicholone
This gentle-looking snail is actually the most poisonous creature on Earth. Textile conical snails fork their prey with hollow teeth and inject deadly toxins through their teeth. They usually prey on molluscs, and snails eat their own kind when there is not enough food. Photo by De Agostini / Getty Pictures
The oversized head and a large mouth full of folds make the toad look bad, and in fact it is really not easy to mess with. This camouflage artist who lives on the ocean floor can crush the shells of mollusks using sturdy jaws and teeth and devour oysters, crabs, shrimp, squid, fish, and many other marine life. But male toads also have a tender side. They guard their nests and even take care of them during the weeks that the juveniles are born. Photography: Marilyn and Maris Kazmers/Seapics.com
Now let's introduce a group of white-spotted spiny seabream that live around the coral reefs of Kiribati in Micronesia. The 75 species of spotted spiny seabream in the world have scalpel-like movable stingers on each side of their tails, and both fish and curious humans are at risk of being attacked by stingers. Despite being born with this weapon, the thorn-tailed seabream is not fierce in temperament. Most of them are herbivores that feed on marine algae. Photograph: Paul Nicholone
Maxillary needlefish are commonly found in tropical and subtropical seas. But once they float out of the sea and fly, they turn into a sharp dagger. Although very rare, humans can feel pain or even be killed if stabbed. Fishermen who travel at night face greater danger because the lights attract needlefish. Photographed by David Dolbyle
Taro snails are notorious for stabbing divers who want to pick up their beautiful shells. But the snail took its poisoning method to a whole new level — it was the most poisonous of all snails, and several people had already died from its attacks. Once the fish fall into a hypoglycemic coma, the snail will use a "prosthetic mouth" to reach the target — it looks like it is throwing a cloak at its prey and dragging the stupid animal into its mouth. The snail will then stab the fish with another set of toxins to ensure that the victim is completely paralyzed. PHOTOGRAPH BY DESIGN PICS INC/NAT GEO IMAGE COLLECTION