West Indian Manatee

Commonly called a sea cow, the docile manatee has adapted well to its herbivorous life-style. Dexterous flippers, with their vestigial nails, help the animal to grasp and dig up deeply rooted aquatic plants. Because most of these plants contain silica, which wears the teeth down quickly, manatees have a unique dental solution: at a rate of about 1 mm (0.039 in) a month, the molars move towards the front of the jaw. They fall out when completely worn and are replaced by new teeth at the back of the jaw.

Godfrey Merlen/Oxford Scientific Films

Bottle-Nosed Dolphins

Bottlenose Dolphins

Dolphin Research Institute, Inc

Dolphin - The Oracles of the Sea

Speeches by Newton L. Gingrich  

The bottle-nosed dolphin belongs to a group of marine mammals known as the toothed whales (Odontoceti). It has a pronounced beak, high dorsal fin, and broad tail flukes. Bottle-nosed dolphins are approximately 1.2 m (4 ft) long at birth and grow to a maximum size of 3 to 4 m (10 to 13 ft). There are 32 species of dolphins found throughout the world in all oceans and seas except arctic and antarctic waters. Several freshwater species are also known.

Dorling Kindersley

Common Dolphin

The common dolphin, Delphinus delphis, is found world-wide in tropical and warm temperate waters. It travels in schools that sometimes number in their hundreds or even thousands. Females give birth to a single calf about 95 cm (3 ft) in length. Adults grow to 2.5 m (8 ft) in length and 175 kg (385 lb) in weight. Common dolphins can swim at speeds of over 35 km/h (20 mph).

K. Findlay, Zoology Department/University of Cape Town

Tidal Pool

The fluctuation of the tide allows for a unique environment along shorelines. The current continually circulates and replenishes a rich supply of nutrients along beaches, but organisms living there must be adapted to both buffeting waves and frequent shifts from open air to complete submersion. Marine organisms adapt to the constantly changing surroundings in a variety of ways. Starfish use suction-cup feet, barnacles fix permanently to large objects like rocks and boats, and seaweed anchors firmly to the ocean floor. When the tide goes out, pockets of water remain trapped in rocks, depressions in the sand, and natural basins called tidal pools, like the one shown here during low tide.

Pat O'Hara Photography

Mudskipper

Mudskippers are fish that can propel themselves over land by using their pectoral fins as legs. They can remain out of water for several days by breathing air trapped in highly vascularized cavities in the mouth and gill chambers. They use this special ability to feed on the rich supply of crustaceans present in the mud of mangrove swamps and estuaries. Mudskippers inhabit the tropical coastal regions in the Indian and Pacific oceans.

Zig Leszczynski/Animals Animals

Scallop

Scallops are bivalve molluscs related to oysters, clams, and mussels. The circular white muscle tissue dominating the interior of the shell has a flavour and texture that make the scallop one of the most prized of all seafoods.

Dorling Kindersley

Spiny Buffer

The spiny puffer, or burrfish, has a unique defensive mechanism that protects it from predators. When threatened, it inflates its body with water or air, which erects the numerous long spines covering its body. The inflated body and the sharp spines make it difficult for a predator to swallow the puffer. When the danger has passed, the puffer slowly deflates itself and resumes a more normal shape.

J.W. Mowbray/Photo Researchers, Inc.

Stonefish

With venom powerful enough to kill human beings, stonefish are the deadliest fish in the sea. Their squat bodies camouflage them well against coral and mud and allow them to surprise small fish and other prey. Found in tropical waters, stonefish use their poisonous spines only in self-defence.

Carl Roessler/Bruce Coleman, Inc.

Lionfish

The venomous lionfish, Pterois miles, is the most spectacular member of the rockfish, or scorpion-fish, family. Its elaborate fins are supported by long, thin, hollow spines, each of which is connected to a venom sac. When threatened by a predator or handled by humans, these spines act like hypodermic needles, injecting the intruder with a toxin that causes excruciating pain and results in swelling.

C. Velasquez, Zoology Department/University of Cape Town

Sea Spider

Introduction to the Pycnogonida

Sea spiders are marine species found from the intertidal region to the deep-sea floor. They have two pairs of eyes, three pairs of legs, and sex organs located in the legs.

Doug Allan/Oxford Scientific Films

Manta Ray

The manta ray, or devilfish, is the largest species of ray, growing to a width of at least 6 m (20 ft) and a weight of more than 750 kg (1,500 lb). In spite of its large size, the manta ray is a filter feeder, straining planktonic organisms and small fish out of the water with its wide, gaping mouth. Unlike other types of rays, the manta ray lacks a spine on its tail.

Howard Hall/Oxford Scientific Films

Globular Sponges

Introduction to Porifera

The globular sponges pictured here were found off the islands of Indonesia. The calcareous (containing or consisting of calcium) deposits left by these and other sponges help build reefs.

Dale Knuepfer/Bruce Coleman, Inc.

Purple and Yellow Tube Sponge

Introduction to Porifera

The purple and yellow tube sponge displays one of the many different body forms typical of sponges. Sponges, considered to be the most primitive of the multicellular animals, are represented in the fossil record back to the Cambrian Period, at least 570 million years ago. The interior body cavities of sponges provide shelter for a variety of small crabs, sea stars, and other marine invertebrates.

Joe Dorsey/Oxford Scientific Films