Common Name: Sponge
Scientific Name: Demospongiae
Size: 1cm - 3m (0.4in - 118in)
Number of Species: 5,000
Lifespan: 15-30 years
When you see the skeletons of sponges on the beach, it is hard to imagine, firstly, that they are animals and, secondly, their incredible colours and diversity underwater. Greek philosopher Aristotle was the first to recognise, some 2000 years ago, that sponges were animals. In the sixteenth century they were thought to be solidified sea foam.
What does a sponge look like?
Living sponges look nothing like the bathroom sponge, which is only the skeleton of one particular group of sponges. The colours include pink, blue, yellow, white, orange and purple. The smallest sponges are only a millimetre high when fully grown and the largest sponge is about as big as a medium-sized barrel. Near the shore, sponges tend to encrust rocks and other structures. In shallow and deep seas, the forms vary from spherical, finger-shaped, bushy or tree-like, tubular, cup-shaped or funnel-shaped. Their texture varies from soft and readily compressible to as hard as stone. The characteristic feature of a sponge is that it bears one or more conspicuous rounded openings. Under a microscope, the rest of the surface is seen to be punctured with minute pores. Where do they live?
Where do sponges live?
Sponges are thought to have evolved around 500 million years ago, and today there are more than 5,000 known species of sponge with another 5,000 species thought to have not yet been discovered. Most sponges live in a salt water environment, attached to objects on the sea floor. Less than 200 sponge species inhabit freshwater habitats. Sponges grow virtually anywhere in the ocean where they can gain a firm hold and are found in large numbers from mid-tide level near the shore down to great depths. Colourful sponge gardens are found in all of Western Australia’s marine parks, including some remarkable deep water sponge gardens recently discovered at Ningaloo Marine Park.
What does a sponges eat?
Sponges have no organs, and obtain their nutrition from the water that is continuously flowing through them. Sponges can be found in variety of different sizes and shapes tubes, fans, cups, cones and blobs. Sponges are omnivorous animals that obtain their nutrition from the food particles in the water. Sponges primarily eat bacteria, phytoplankton and bits out of the water. A number of sponge species are known to have a more carnivorous diet, eating small fish and crustaceans on the reefs.
What are the natural enemies of the sponges?
Due to the abundance and variety of sponges, they are preyed upon by many animals. The fact that sponges move so slowly, if at all, means that they cannot avoid being eaten. Sea turtles, crustaceans, fish and echinoderms all prey on sponges.
How fast is a sponge?
Sponges are very slow-moving animals that are found across the sea floor. Although many sponges actually move less than a millimetre a day, some adult sponges are actually sessile, which means that they are fixed onto something and do not move at all.
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