Information about Coral Reef Animals

The garden-like appearance of coral reefs is due to coral reef animals not plants. Though firmly fixed to the substrate they are nonetheless animals. They depend on other organisms or plants for nutrition and most have organs such as muscles and stomachs. The coral reef animals also usually have a mobile free-swimming larval stage by which they disperse before settling down to attached life as adults.

From our Earthly perspective, attached animals are hard to imagine. On land, extremes of temperature and irregular availability of food and water make mobility a universal necessity for animal life. To us land dwellers, we associate animals with movement - where animals move about to find their food. Only plants are fixed to one spot. In the sea, however, immobile animals firmly rooted to the substrate are common on coral reefs.

Here temperature is buffered, currents carry a flow of nutrition and drought is not even an idea. A wide variety of both primitive as well as some more advanced forms of life have adapted to an attached lifestyle either filtering the water for plankton and organic debris or subsisting with the aid of symbiotic plant cells living in their own tissues.

The diversity of coral reef animals is remarkable. Sponges run the gamut from shapeless lumps, bumps and clumps, to fans, tubes and fluted cylinders. They all, however, passively filter the water with little that is recognisable as animal behaviour. Cnidarians (the corals, anemones and their relatives) not only take the form of flowers, mushrooms, bushes and trees, but strange shapes like a human brain, broccoli and lettuce. Their behaviour consists of simple reflexes such as retracting their polyps when touched. More advanced invertebrates such as tube worms, clams and sea squirts are more recognisably animal with organs such as hearts and kidneys and more complex behaviour, including the instantaneous reflexes we associate with land animals.

In addition to mind-boggling diversity, reef gardens surpass anything on land in delicacy and colour. Supported by water, living tissue can, and does, take the most extravagant and flimsy of forms. Colour, too, has run amok in attached reef creatures. Unlike land plants where bright colours are largely restricted to flowers, in the reef gardens entire organisms are brightly hued with every colour of the spectrum. The end result is a magical fairytale world where the extravagant and bizarre are commonplace for our coral reef animals.

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