Nematodes, or roundworms, are part of the phylum Nematoda which is one of the most diverse phyla and it has been argued that the phylum should be split into different groups. They are extremely hard to distinguish and there are about 28,000 species that have been clearly identified and 16,000 of them are parasitic. Nematodes have adapted to almost every fresh water habitat and other habitats as well.
Turbatrix aceti (vinegar eel)
The digestive system of a vinegar eel is quite simple and it is basically a long tube with the mouth at the tip and the anus at the end. The digestive tract is efficient and it goes in one direction and it is also where the food gets broken down and the nutrients are absorbed. Vinegar eels’ diet includes the bacteria from apples and vinegar. The food would go in an intestine that is like the pharynx in the human body, and there are nerves that go around the pharynx. The waste is removed in the anus.
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Ascaris lumbricoides (roundworms)
The roundworm has a definite digestive systems that runs through the length of their bodies. Many are parasites and live off animals and plants and have a mouth with pharyngeal muscles. It contains and mouth, pharynx and anus and when they look to eat they have to use their pharyngeal muscles to absorb the food. When the food is absorbed, digestive juices can be used in helping break down the food. And finally when the food is going through the digestive process the food is broken down and digested.
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Trichuris trichiura (whipworm)
All of the digestive system is contained in the head. The whipworm feeds and its food enters through its mouth and like flatworms, they lack an anus so whatever enters through the moth, also leaves through the mouth as well. The food is broken down inside of the digestive tract and is then released through the mouth.
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