The Great Barrier Reef is the largest coral reef in the world. It consists of more than 2,900 coral reefs, 600 continental islands, 300 coral cays and thousands of species making it one of the world's most complex and diverse ecosystems. The animals of the Great Barrier Reef include some 1500 species of marine fish, 360 species of hard corals, between 5000 and 8000 species of mollusks, 600 species of echinoderms, 17 species of sea snakes, 1500 species of sponges, 30 species of whales and dolphins, 6 species of marine turtles, 22 species of seabirds and 32 species of shorebirds which breed on the reef's many small islands.
The sections below discuss a few of the many animals of the Great Barrier Reef:
Marine Fish of the Great Barrier Reef
There are more than 1500 species of fish that inhabit the Great Barrier Reef. They range in size from the tiny gobies, some of which weigh less than one gram, to the larger bony fishes such as the tuskfish and potato cod, to the massive cartilaginous fishes such as manta rays, tiger sharks and whale sharks. Damselfish, wrasses and tuskfish are among the most abundant fishes on the reef. Other fish of the Great Barrier Reef include blennies, butterfly fish, triggerfish, cowfish, pufferfish, angelfish, anemone fish, coral trout, seahorses, sea perch, sole, scorpion fish, hawkfish and surgeonfish.
Hard Corals of the Great Barrier Reef
The Great Barrier Reef is home to about 360 species of hard corals including bottlebrush coral, bubble coral, brain coral, mushroom coral, staghorn coral, tabletop coral and needle coral. Hard corals, also known as stony corals, are a group of marine animals that live in shallow tropical waters and are responsible for building the structure of a coral reef. Colonies of hard corals grow in various shapes and sizes such as mounds, plates and branches. As previous coral colonies die, new ones grow on top of the limestone skeletons of their predecessors. Over time, this growth creates the three-dimensional architecture of a coral reef. Colonies of hard corals consist of thousands of small individal invertebrates referred to as coral polyps. Each polyp is radially symmetrical with a tube-like body that has a tentacle-rimmed mouth at the tip that it uses to feed.
Sponges and Echinoderms of the Great Barrier Reef
Over 600 species of echinoderms and more than 1500 species of sponges inhabit the Great Barrier Reef.
Echinoderms are bottom-dwelling marine invertebrates. They exhibit a type of radial symmetry called pentamerous symmetry in which their body can be divided into five equal parts around a central axis. The echinoderms of the Great Barrier Reef include sea urchins, sea cucumbers, sea stars, feather stars and brittle stars.
Sponges of the Great Barrier Reef include the yellow burrowing sponge, tubular sponge, thick yellow fan sponge.
Marine Reptiles of the Great Barrier Reef
There are 23 species of marine reptiles that inhabit the Great Barrier Reef including 6 species of sea turtles and 17 species of sea snakes. Occasionally, the saltwater crocodile also ventures out to forage on the reef, although such visits are quite rare.
The sea turtles that inhabit the Great Barrier Reef include the green turtle, loggerhead turtle, hawksbill turtle, flatback turtle, leatherback turtle and the Pacific ridley turtle. Some sea turtle species, such as the green turtle, loggerhead turtle and hawksbill turtle, nest on coral cays. The flatback turtle nests on continental islands and the green and leatherback turtles nest on mainland Australia. When not nesting, these sea turtle species use the waters of the Great Barrier Reef as foraging grounds.
Among the sea snakes of the Great Barrier Reef are the olive sea snake, the turtle-headed sea snake and the sea krait. All sea snakes are venomous.
Marine Mammals of the Great Barrier Reef
About 30 species of whales and dolphins frequent the waters of the Great Barrier Reef including humpback whales, Irrawaddy river dolphins, minke whales and spinner dolphins. Dugongs also inhabit the reef, feeding on the sea grasses that grow in the shallow inshore waters.
Not all of these marine mammals are permanent residents of the Great Barrier Reef. Minke whales and humpback whales visit the reef in winter. Other rorqual whales such as blue whales, fin whales and sei whales also migrate through the Great Barrier Reef region but do not stay for extended periods of time.