The nematode digestive system is generally separated into three parts, the stomodeum, intestine, and proctodeum. The stomodeum consists of the “mouth and lips”, buccal cavity, and the pharynx (esophagus). Each of these regions are used extensively in taxonomy as well as classification of nematodes, and for providing as indication of feeding habit or trophic group.
Ascaris (Ascarids)
The ascarid is a parasitic worm that invades organism's bodies and are harmful to humans. The digestive system of an ascarid consists of four parts: Alimentary Canal, Mouth, Pharynx, and Intestine. The alimentary canal compromises a short pharynx or esophagus representing the foregut, a long intestine or mod-gut, and a short rectum or hind gut. The mouth is a triradiat aperture, situated at the anterior tip guarded by three lips or labia. The pharynx contains an outer membrane and inner lining in which between the outer end of each ray of the lumen, tri-radiate, and the outer bounding membrane extend the tissue fibers, known as marginal fibers, which help in preserving the tri-radiate form of the lumen. The intestine is dorsoventrally flattened and its wall contains a single layer of tall columnar cell lined externally by a basement membrane and a thin layer of cuticle. The free inner margin of each cell is produced into several finger-like projections, the microvilli, forming a brush border, increasing the surface area.
The ascarid feeds on whatever is in the stomach of an organism, whether it is broken down or not. It can eat anything that is taken into the stomach or intestines whether it may be vegetables, meat, or snacks. It resides in the gastrointestinal tract of humans and feeds on any intestinal contents such as partially digested food and other matter. It is parasitic, so it takes in through the mouth whatever is in the human stomach at the time. |
Enterobius (Filarias, Hookworms, Pinworms)
The digestive system is similar to that of the ascarid in that it does have a complete digestive system and it is parasitic. The hookworm has six lips that surround the mouth opening as well as the buccal cavity that leads from the mouth to the esophagus. What happen is that food is sucked from the esophagus or pharynx into and through the esophagus. The sucking is necessary to force food through the intestine against the high pressure found in the pseudocoel. Glands are found among the muscles in the system and they open into the lumen of the esophagus. Hookworms secrete anticoagulants with these glands in use. Also, the hookworm takes in food through the intestine which stretches from the esophagus to the proctodeum and is a simple, tube-like structure made of a single layer of cells. Just about all of the digestive functions that occur in a hookworm occur in any other nematodes in which hookworms are just as parasitic.
The feeding style of the hookworm is relatively different to that of the ascarid but similar, in a way, to that of the leech. Hookworms can attach themselves to the intestinal lining in a creature and, therefore, can feed off of the blood vessels in the intestines. They live off of the blood in the creature that they infect which is one of the actual harmful effects of having a hookworm in your body. They have six sharp teeth and burrow through different organs in the body such as the lung tissue, and they hang onto the intestinal wall with their teeth and suck the blood of the organism. Some are able to absorb food through the skin, and most leave bite marks at where they've been which causes the blood to seep out of the internal wound, which is why the hookworm spends its life sucking blood and mating. |
Trichuris Trichiura (Whipworms)
The whipworm is a parasitic nematode that is very similar to the hookworm in its digestive parts and such, but is quite different in its actual digestive breakdown of its food. For one thing, the digestive system of a whipworm is all contained in the head. The whipworm first feeds, in which it obviously enters through its mouth. What happens next is that the food is broken down in the digestive tract and is eventually released. Since the mouth is the only main hole in the whipworm, the food is released through the mouth as waste. The difference with this worm is that it cannot absorb food or nutrients through the skin like the hookworm can since all of its digestive parts are located in the head.
Whipworms are usually found in pets such as cats or dogs, but can be found in humans as well. Similar to hookworms, whipworms also burrow into the intestines of the body as well. They can come back out and pass into the cecum, a space between the small and large intestine where they'll make their home and lay eggs in the intestines. Like hookworms, they feed off of blood and intestinal matter and lay eggs in the intestines to hatch and eat more of the matter. |