What is the coelom of the earthworm

Physique and sense organs

Earthworms developed around 200 million years ago and are considered to be the largest invertebrates on the ground. A closer look shows that the earthworm is much more than an elastic, water-filled muscle tube and has various special features.

Our earthworm species are characterized by their elongated, rotating body. The worm body is made up of up to 200 identically designed sections or segments that we perceive externally as curling. Only in the front third of the worm does the internal blueprint differ from that of the other body segments due to the additional digestive and reproductive organs.
The largest species reach a length of about 30 cm. The skin is smooth, slightly iridescent and colored differently. The color palette ranges from reddish brown or almost black through various greenish colors to wine red. The mucous layer of the skin serves as a protection against drying out and as a lubricant when crawling.
The ring and longitudinal muscles are located under the skin. Intestines, abdominal nerve cord, abdominal and spinal blood vessels run through the entire skin-muscle tube from front to back. The rest of the body cavity is filled with body fluid.

Sense organs
The earthworms have neither lungs nor gills, they breathe through the surface of the body. The blood flows in fine vessels under the constantly moist skin and exchanges breathing gases here. So earthworms do not drown when rain fills their tunnels, as long as there is enough oxygen in the water. Like humans, earthworms have red blood, which circulates in a closed blood vessel system, driven by 5 pairs of Ā«heartsĀ».
Earthworms neither have eyes nor ears, nor do they have a nose. However, along with various other simple sense organs, they are specially adapted to life in the soil. Using light sensory cells at the front and rear end, they can differentiate between light and dark. So that they can find their way in the dark of the earth and in their living tubes, they orientate themselves with the help of a sense of touch and gravity.
Gaps and obstacles as well as the top and bottom in the ground can be easily located. Ground vibrations are perceived with the sense of pressure. This enables the timely escape from an approaching predator, for example a mole. Sensory buds in the oral cavity and on the skin are used to perceive taste. The earthworm's sense of taste is very well developed because it is as picky about food as a gourmet.