Octopus

In search of the Giant Octopus

The Common Sand Dollar

The Life History of the Bluefish  

Anglerfish

Anglerfish have appendages that serve as "fishing rods," or lures to attract prey, mainly other fish. They are found in oceans throughout the world and generally inhabit deep waters. Certain species can grow to lengths of about 1.5 m (5 ft), and have huge mouths capable of swallowing prey as large as the anglerfish itself.

Zig Leszczynski/Animals Animals

Seaweed

Palmaria palmata  (Linnaeus) Kuntze

Seaweed

Seaweeding: Garden Under Sea

Lantern fish

Lanternfish derive their name from the light-producing organs, or photophores, on their bodies. The function of the photophores is not fully understood, although each species has a characteristic arrangement of photophores, which is an important means of species identification. Lanternfish are deep-sea fish, but migrate to surface waters to feed at night.

Dr. Paul A. Zahl/Photo Researchers, Inc.

Beluga Whale

Beluga Whale

Also called "canaries of the sea" because of their loud, shrill squeaks and chirps, beluga whales live in the upper parts of the northern hemisphere, in estuaries and near pack ice. The "hump" at the front of the beluga whale’s head changes shape and size in accordance with the different sounds emitted by the whale. In North America, belugas are popular attractions in public aquariums and oceanariums because of their playful and "talkative" demeanour.

Tom McHugh/Photo Researchers, Inc.

Diatoms

Diatoms: Phytoplankton made of glass

Introduction to the  Bacillariophyta

Diatoms represent a significant group of marine plant making up the phylum Bacillariophyta. They are single-celled and have a cell wall made of silica, which is essentially glass. The diatoms, and other aquatic single-celled plants, form the phytoplankton, which are the base of the marine food chain.

Peter Parks/Oxford Scientific Films

Hammerhead Shark

The hammerhead shark, distinguished by the lateral expansion of the head into a hammer-shaped structure, on the ends of which are placed the eyes and nostrils, is perhaps the most easily recognized of the 360 or so species of living sharks. The great hammerhead roams tropical and subtropical seas feeding on stingrays, bony fish, and invertebrates. It is known for its unprovoked attacks on humans.

F. Stuart Westmorland

River Lamprey

The river lamprey is one of a number of lampreys common to North America and its surrounding waters. Most species of river lamprey are not parasitic. All lampreys spend the first four years of their lives, during which they are known as ammoecetes larvae, living as filter feeders buried in the mud at the mouths of small streams and rivers. Eventually they metamorphose into the adult form. In nonparasitic lampreys, such as the river lamprey, the adult stage does not feed; it merely spawns and dies. The lamprey shown here is facing the viewer with its mouth completely open.

Oxford Scientific Films

Sea Lamprey Clings to a fish

The sea lamprey, a vertebrate parasite, belongs to the most primitive group of living fish, the agnathans, or jawless fish. In this species the lower jaw is missing and the upper jaw is modified into a sucking disc. The lamprey feeds on blood by using this disc to attach itself to another fish and drilling a small hole into the fish’s side with its small, muscular tongue. The parasitic action rarely kills the host, but wounds caused by lampreys often become infected.

Berthoule/Photo Researchers, Inc.

Polar Bear on an Ice Floe

Polar Bears (Sea World)

Polar Bears (The Bear Den)

The polar bear, the largest of the terrestrial carnivores, is found along the northernmost coasts of the northern hemisphere as well as on sea ice and islands. Polar bears are strong swimmers, paddling with their front legs and steering with the back legs. They have been known to swim as far as 80 km (50 mi). On land polar bears easily cover distances of up to 80 km (50 mi) a day and 1,100 kilometres (690 mi) a year.

Konrad Wothe/Oxford Scientific Films

Polar Bear, Manitoba

Polar Bears (Sea World)

Polar Bears (The Bear Den)

Polar bears congregate on the snow-covered shores of Hudson Bay in the north-east of the Canadian province of Manitoba. Despite their reputation as fierce wild predators, polar bears have become well adapted to the human presence in some areas of northern Canada, raiding domestic rubbish and providing a popular sight for tourists.

Dan Guravich/Manitoba Department of Natural Resources

Generalized Anatomy of a Crustacean

A crustacean’s body cavity is little more than a dorsal heart and a blood circulatory system. In the tubular gut, which leads to the anus in the tail portion, can be found the two digestive glands. Near the sense organs sits the brain which is in the form of ganglia. A collection of ganglia and major nerves is found below the gut.

Dorling Kindersley

Hydrozoan's Jellyfish 

The notorious Portuguese man-of-war, Physalia physalia, a hydrozoan jellyfish, is propelled on the surface of warm seas by the force of the wind on its blue, gas-filled float. Stinging tentacles, as long as 20 metres (65 ft) or more, hang from polyps on the underside of the float. These tentacles contain nematocysts, capsules that launch toxic, numbing threads for capturing prey, which can seriously and even fatally injure people. Stinging polyps transfer prey to feeding polyps for digestion.

Peter Parks/Oxford Scientific Films

Obelia Colony

Cnidarians of the genus Obelia form colonies of polyps in one stage of their asexual reproduction. There are two kinds of polyps, feeding and reproductive. They bud but do not separate from an upright, anchored stalk, remaining instead as the branchlike structures seen in this picture. Each polyp, called a subindividual because its activity is governed by that of the entire colony, has a transparent, horny covering into which it can withdraw. The two types of polyp differ in other aspects of their structure. Only feeding polyps have tentacles with which to draw food towards them, but because both types of polyp are hollow, partially digested food can travel through the colony’s continuous digestive cavity to nourish the reproductive polyps. The medusa, or sexual stage of the organism, emerges from the opening of the reproductive polyp as a saucer-shaped mass of jelly.

Peter Parks/Oxford Scientific Films