Earthworm Body Systems

Crashnibbles By Crashnibbles, 15th Jan 2011 | Follow this author | RSS Feed | Short URL
Posted in Wikinut>Guides>Science>Nature

This is an article about annelids, or segmented worms like earthworms.


Annelid means segmented worms. These are like leeches, sandworms, and earthworms (the kind you use to fish, or possibly to eat). They are in the kingdom Animalia (animals) and the phylum annelids (not technical/scientifically exact term with the Latin ending). They have little rings (segments). I will focus mainly on worms (particularly earth worms). Let’s get to whatever it was we were going to do next now!

Earthworms live in the soil, but some other annelids can live in the ocean/sea or freshwater rivers/lakes. To move they have a lot of segments (bet you didn’t know that yet…). These allow for flexibility. Mucus on the outside of the worm’s body, and this helps the worm to glide around on top of and inside of the soil. They have setae or bristles on each segment. These are used to pull them along so they will extend in one direction and then pull the other end towards the direction they were going. This lets them move in a direction instead of just extending and contracting whilst not moving anywhere.

Worms eat dirt, which is largely available in the ground as well as under it. They also eat leaves and stuff like that. They take the particles of organic matter that came in the ground, so worms are usually only 5 feet down at most for it is hard for leaves to get 5 feet under ground. This goes in their mouth. Then it travels down the pharynx and esophagus before it enters the crop. This is a storing place for food to go to for a while. Then it goes to the gizzard which grinds the food up. Then it goes in the intestines which send nutrients into the blood vessels. Waste stuff is gotten rid of through the anus. Worms have a complete digestive tract that has food go in one way and waste go out another way. Less complicated organisms typically don’t have this (like flatworms and sponges, which are very basic).

Worms have closed circulatory systems. All of their body fluids are in small vessels that carry blood with nutrients to the body. They have 5 simple hearts called aortic arches.

Worms get oxygen via absorption through the skin. Carbon dioxide is made and leaves out the skin. If the skin is moist or the worm is in the sun and dries out, the gases can’t exchange and the worm will die of suffocation.

Their nervous system is very sensitive to their habitat/environment. They can detect light and produce a chemical (mucus) that warns other worms. They also use the mucus to run away faster.

Worms are hermaphrodites, for they have male and female reproductive organs. They cannot fertilize themselves though. When mating, 2 worms exchange sperm. This is stored until the eggs are about to be released. Then the sperm fertilizes the eggs which are laid by the worm in a slimy casing. Then young worms break out of it and crawl away.


Body, Life, Systems, Worms

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