Nematoda,
Introduction
There are thousands of nematodes. Not only are there more than 15,000 known species of roundworms, but there are many thousands of individual nematodes in even a single handful of garden soil. And they keep coming! Some species of roundworm may contain more than 27 million eggs at one time and lay more than 200,000 of them in a single day. Some scientists have estimated that there may be as many as half a million more unkown species of roundworm yet to be discovered, an estimate based on the fact that many new species are still being discovered, that relatively few people are looking for more species, and that most roundworms look pretty much alike. If the estimated number of species is anywhere close to correct, it would mean that roundworms are the second most diverse group of animals, trailing behind only the arthropods.
Nervous System
Four peripheral nerves run the length of the body on the dorsal, ventral, and lateral surfaces. Each nerve lies within a cord of connective tissue lying beneath the cuticle and between the muscle cells. The ventral nerve is the largest, and has a double structure forward of the excretorypore. The dorsal nerve is responsible for motor control, while the lateral nerves are sensory, and the ventral combines both functions. At the anterior end of the animal, the nerves branch from a dense, circular nerve ring surrounding the pharynx, and serving as the brain. Smaller nerves run forward from the ring to supply the sensory organs of the head. The body of nematodes is covered in numerous sensory bristles and papillae that together provide a sense of touch. Behind the sensory bristles on the head lie two small pits, or 'amphids'. These are well supplied with nerve cells, and are probably chemoreception organs. A few aquatic nematodes possess what appear to be pigmented eye-spots, but is unclear whether or not these are actually sensory in nature
![Picture](/uploads/1/1/5/0/11508385/1336090428.jpg)
Vinegar eels
Tiny free living worms that can live in vinegar or liquids that can become vinegary such as cider, wine, beer etc. There are many interesting facts connected to vinegar eels such as they like to live in an environment 60-90 degrees. They have adapted to living in places with low PH. They give birth to live young as many as 45, every 8-10 days. Many people think vinegar eels are really eels. But it’s hard to be related to large swimming animals when you’re microscopic. Some microorganisms are cannibalistic. Not vinegar eels! They eat fermented apples
Tiny free living worms that can live in vinegar or liquids that can become vinegary such as cider, wine, beer etc. There are many interesting facts connected to vinegar eels such as they like to live in an environment 60-90 degrees. They have adapted to living in places with low PH. They give birth to live young as many as 45, every 8-10 days. Many people think vinegar eels are really eels. But it’s hard to be related to large swimming animals when you’re microscopic. Some microorganisms are cannibalistic. Not vinegar eels! They eat fermented apples
![Picture](/uploads/1/1/5/0/11508385/9979709.jpg?1336090536)
Caenorhabditis elegans
A 1mm long free living nematode that has been used for many years (starting in 1974) as a "model organism" for scientific research. At maturity all individuals have exactly 959 cells. It was the first multicellular organism to have its complete genome sequenced (in 1998), so leading ultimately to the "Human Genome Project." The nematode Caenorhabditis elegans is a multicellular organism that is utilized as a model system to address fundamental questions in developmental biology, neurobiology and behavioral biology. One of the key strengths of the model system is that sophisticated genetic approaches can be applied to address questions of interest.
A 1mm long free living nematode that has been used for many years (starting in 1974) as a "model organism" for scientific research. At maturity all individuals have exactly 959 cells. It was the first multicellular organism to have its complete genome sequenced (in 1998), so leading ultimately to the "Human Genome Project." The nematode Caenorhabditis elegans is a multicellular organism that is utilized as a model system to address fundamental questions in developmental biology, neurobiology and behavioral biology. One of the key strengths of the model system is that sophisticated genetic approaches can be applied to address questions of interest.
![Picture](/uploads/1/1/5/0/11508385/7793488.jpg?1336090909)
Toxocara canis
Toxocara canis is smaller than most of the other species in the family Ascarididae. It has a complete gut in the form of a simple tube. It is a "round worm" implying the shape of the outer layer to be round (if seen in a cross section ). Depending on the host the worm gets into T. canis will have different number of larval stages. Most worms have three larval stages before becoming infective.Both males and females have three prominent lips. Each lip has a dentigerous ridge. The lateral hypodermal cords are visible with the naked eye. No gubernacullum is present. In both sexes there are prominent cervical alae. The eggs are brownish and almost spherical. The eggs measure 75-90 micrometers. The eggs are embryonated when laid and have surficial pits. These eggs are very resistant to various weather and chemical conditions.
Toxocara canis is smaller than most of the other species in the family Ascarididae. It has a complete gut in the form of a simple tube. It is a "round worm" implying the shape of the outer layer to be round (if seen in a cross section ). Depending on the host the worm gets into T. canis will have different number of larval stages. Most worms have three larval stages before becoming infective.Both males and females have three prominent lips. Each lip has a dentigerous ridge. The lateral hypodermal cords are visible with the naked eye. No gubernacullum is present. In both sexes there are prominent cervical alae. The eggs are brownish and almost spherical. The eggs measure 75-90 micrometers. The eggs are embryonated when laid and have surficial pits. These eggs are very resistant to various weather and chemical conditions.