A crinoid on an orange
sponge from the |
A barrel sponge from the Bioinfo Animal Pictures Archive |
There are about 5,000 species of sponges found throughout the world. Most sponges are found in oceans, although some groups are found in fresh waters such as lakes. They were the first group of animals that has specialized cells to do special jobs. However, the cells are not so advanced as to form tissues. Sponges live singly or in colonies.
Many sponges give off a toxic or poisonous substance. This is used to fight off enemies and poison them. However, some of the substances given off are used by humans as medicines. The skeleton of the sponge is used by man for sponges as well.
Some sponges appear green because algae clings to them. The algae provide oxygen for the sponge and the sponge provides carbon dioxide for the algae. When two living things live off of one another, it is called symbiosis.
Here is how a sponge's
systems are organized
System
Type
|
Sponges
System
|
Muscular-Skeletal | A sponge is a hollow tube with many pores or openings. The skeleton is made of lime or silicon. |
Digestion | A sponge takes in food via the water that flows through the pores. |
Nervous | A sponge has a very low level reaction to the world around it and does not have a brain per se. |
Circulation | A sponge has water flow in through the pores. The water contains the food and oxygen the sponge needs. |
Respiration | A sponge takes in water through its pores and in more advanced forms, with canals that move the water to all throughout the sponge. Then the oxygen from the water is used. |
Reproduction | A sponge reproduces by budding and also sexually. |
Excretion | A sponge has carbon dioxide and other wastes removed as the water moves in and out through the pores. |
Symmetry | A sponge has either radial symmetry or is asymmetrical. |
Coloration | A sponge is white, red, orange, green, yellow, brown, purple, black |