It is interesting to know the anatomy of an earthworm. An earthworm is just a slimy, crawling, feetless and elongated soft-bodied creature which are generally red or earth tone in colour and can measure upto 8 to 10 inches in length.
They are soft to the touch and often seek refuge in burrows or soil and under rocks, fallen logs or branches. Their diet ranges from soil and gravel to decaying matter, leaves and rotting wood and animal manure.
The body structure is basically as follows:
An earthworm is invertebrate, meaning it has no bones or skeleton in its body. Its body consists of muscular segments and it has bristles on each segment called setae that help the earthworm move. These bristle can help you to determine which end is the head. When you run your fingers down its underside, if its feels smooth, you are moving towards the tail. Any roughness, meaning you are moving towards the head.
Movement Earthworm has no limbs. It has two sets of muscles; one that makes it long and thin and the other one that makes it fat and short. When it want to move, the earthworm will alternate the use of its long and muscular muscle and this will create movement for its body to be pushed forward in the soil or ground.
An earthworm has a digestive system. It eats dirts or leaf using its mouth and pass it through an oesophagus for the food to go down. It will store the food in a crop. Its gizzard will grind the food down and use its intestines for the food to pass through and nutrients will be absorbed and use for the body. It also has a tiny flap called ‘prostomium’, like a top lip which is at the end of its head. This prevent from any unwanted items from entering its mouth which is underneath it directly. Earthworm does not have teeth.
A nervous system of an earthworm consists of a simple brain and nerve cord.
Do you know that an earthworm has blood? It has blood vessels that lead to multiple (5) hearts. An earthworm appears pink or red because its blood is running close to the surface of its skin.
Basically an earthworm has no respiratory organ. So, how does it breath? The oxygen is taken in directly through its skin and it gives off carbon dioxide. Its always maintain a moist skin to absorb air and that is why earthworm prefers the dark and damp soil environment.
An earthworm’s wastes help to fertilize the soil. It gets rid of its wastes through tubes called nephridin that lead to pores that allow the wastes out.
The color of an earthworm is generally earthtones such as brown, red,tan, etc. An earthworm body is structured bilateral symmetry.