PHYLUM NEMATODA (ROUNDWORMS)
• One of the most common multicellular organisms. • They have long, threadlike bodies and are unsegmented.
• The live in almost all environments (especially places with moist soil). • Commonly known as "roundworms."
• They play a major role in decomposition. • 12,000 species
TYPES
There are two main types of nematodes:
Parasitic - hookworms, pinworms, heartworms, Trichinella spiralis, Toxacara canis.
Free Living - Vinegar eels, Caenorhabditis elegans.
SYMMETRY
Bilateral symmetry.
REPRODUCTION
Nematodes produce internally sexually. Nematode sexes are separate for the most part. Even though some are hermaphroditic, two hermaphrodites are still required for true sexually reproduction to occur. Males have a specialized spine that they use for sexual reproduction.
BODY PLAN
Nematodes are pseudocoelomates (see flatworm description). They have a small, slender, cylindrical, and unsegmented body plan that is tapered at both ends.
WHAT IS SPECIAL ABOUT THE ALIMENTARY CANAL?
Nematodes have a complete alimentary canal with a separate mouth and anus at either end of the digestive system. Thus, there is a two-way digestive tract here, which is a totally new trend in animal phylogeny.
CIRCULATORY SYSTEM
Nematodes have no circulatory system.
WHO IS RESPONSIBLE FOR TRICHINOSIS?
The nematode responsible for trichinosis is Trichinella spirilas. Trichinosis is a parasitic disease which is caused by eating raw or undercooked pork. The meat is infected with the larvae of this worm.
TRICHINOSIS TRANSMISSION, SYMPTOMS & TREATMENT
Transmission is caused by eating raw or undercooked pork. Pigs and humans are the main hosts of this female worm. There are two main places where infection can occur: enteral (intestines) or parenteral (outside intestines). Sometimes, in mild cases, there are no symptoms. Yet, after the worm matures in one or two days, symptoms such as nausea, heartburn, vomiting and diarrhea become evident. They can worsen as the larvae move through the tissues and form cysts as they burrow into the muscles of the host, causing edema (excess watery tissue in the body cavities), muscle pain, fever, fatigue and severe muscle pain. It's important to get treatment ASAP. Drugs prescribed for this worm are known as anthelmintics (mebandazole); they are given within three days of infection. Steroids, such as prednisone, are given to relieve the muscle pain. Yet, this whole disaster can be prevented by properly cooking meat. Note to parents: no matter how bratty your kids are, it is morally wrong to punish them by undercooking their meat dinner and giving them Trichinosis. As funny as this might seem, don't do it, please. Thank you.
MY THOUGHTS
The one thing that I find interesting about nematodes is that they can shut down their metabolic process and when conditions are right but still not die. Then, they can "revive" when they are in more favorable conditions. Furthermore, the nematode, Caenorhabditis elegans, has been studied a lot. It was the first multicellular organism from which a complete DNA sequence was obtained. So in a way, it started the famous "Genome Project" that was soon applied to humans as well as other organisms.
• The live in almost all environments (especially places with moist soil). • Commonly known as "roundworms."
• They play a major role in decomposition. • 12,000 species
TYPES
There are two main types of nematodes:
Parasitic - hookworms, pinworms, heartworms, Trichinella spiralis, Toxacara canis.
Free Living - Vinegar eels, Caenorhabditis elegans.
SYMMETRY
Bilateral symmetry.
REPRODUCTION
Nematodes produce internally sexually. Nematode sexes are separate for the most part. Even though some are hermaphroditic, two hermaphrodites are still required for true sexually reproduction to occur. Males have a specialized spine that they use for sexual reproduction.
BODY PLAN
Nematodes are pseudocoelomates (see flatworm description). They have a small, slender, cylindrical, and unsegmented body plan that is tapered at both ends.
WHAT IS SPECIAL ABOUT THE ALIMENTARY CANAL?
Nematodes have a complete alimentary canal with a separate mouth and anus at either end of the digestive system. Thus, there is a two-way digestive tract here, which is a totally new trend in animal phylogeny.
CIRCULATORY SYSTEM
Nematodes have no circulatory system.
WHO IS RESPONSIBLE FOR TRICHINOSIS?
The nematode responsible for trichinosis is Trichinella spirilas. Trichinosis is a parasitic disease which is caused by eating raw or undercooked pork. The meat is infected with the larvae of this worm.
TRICHINOSIS TRANSMISSION, SYMPTOMS & TREATMENT
Transmission is caused by eating raw or undercooked pork. Pigs and humans are the main hosts of this female worm. There are two main places where infection can occur: enteral (intestines) or parenteral (outside intestines). Sometimes, in mild cases, there are no symptoms. Yet, after the worm matures in one or two days, symptoms such as nausea, heartburn, vomiting and diarrhea become evident. They can worsen as the larvae move through the tissues and form cysts as they burrow into the muscles of the host, causing edema (excess watery tissue in the body cavities), muscle pain, fever, fatigue and severe muscle pain. It's important to get treatment ASAP. Drugs prescribed for this worm are known as anthelmintics (mebandazole); they are given within three days of infection. Steroids, such as prednisone, are given to relieve the muscle pain. Yet, this whole disaster can be prevented by properly cooking meat. Note to parents: no matter how bratty your kids are, it is morally wrong to punish them by undercooking their meat dinner and giving them Trichinosis. As funny as this might seem, don't do it, please. Thank you.
MY THOUGHTS
The one thing that I find interesting about nematodes is that they can shut down their metabolic process and when conditions are right but still not die. Then, they can "revive" when they are in more favorable conditions. Furthermore, the nematode, Caenorhabditis elegans, has been studied a lot. It was the first multicellular organism from which a complete DNA sequence was obtained. So in a way, it started the famous "Genome Project" that was soon applied to humans as well as other organisms.