Seeds of the Future
Springing forward
Microbes at the Gas Pump
Tree Frogs
Salamanders and Newts
Not Slippery When Wet
Sea Giants and Island Pygmies
Red Apes in Danger
Two monkeys see a more colorful world
Contemplating thought
Mind-reading Machine
Chemistry and Materials
Big Machine Reveals Small Worlds
Smelly Traps for Lampreys
Revving Up Green Machines
Electronic Paper Turns a Page
Two monkeys see a more colorful world
Computers with Attitude
Dinosaurs and Fossils
Meet your mysterious relative
Have shell, will travel
Ferocious Growth Spurts
E Learning Jamaica
E Learning in Jamaica WIN PRIZES and try our Fun Animated Games
2014 GSAT Results for Jamaican Kids
Results of GSAT are in schools this week
Flower family knows its roots
Wave of Destruction
Deep History
Spotty Survival
Groundwater and the Water Cycle
A Newspaper's Hidden Cost
Finding the Past
Stonehenge Settlement
Settling the Americas
Prehistoric Trips to the Dentist
Electric Eel
Megamouth Sharks
Food and Nutrition
The Essence of Celery
Moving Good Fats from Fish to Mice
In Search of the Perfect French Fry
GSAT English Rules
Problems with Prepositions
Whoever vs. Whomever
Order of Adjectives
GSAT Exam Preparation Jamaica
Results of GSAT are in schools this week
Preparing for the GSAT Exam
Mastering The GSAT Exam
GSAT Exams Jamaica Scholarships
42,000 students will sit for the GSAT Exam in two weeks
2014 GSAT Results for Jamaican Kids
Results of GSAT are in schools this week
GSAT Mathematics
Detecting True Art
GSAT Practice Papers | GSAT Mathematics | Maths
Math Naturals
Human Body
Kids now getting 'adult' disease
Attacking Asthma
Electricity's Spark of Life
African Zebra
The Surprising Meaning and Benefits of Nursery Rhymes
Expert report highlights the importance to parents of reading to children!
Children and Media
Road Bumps
Gaining a Swift Lift
Dreams of Floating in Space
Stalking Plants by Scent
When Fungi and Algae Marry
Plants Travel Wind Highways
Space and Astronomy
Super Star Cluster in the Neighborhood
Supernovas Shed Light on Dark Energy
A Family in Space
Technology and Engineering
Beyond Bar Codes
Algae Motors
Slip Sliming Away
The Parts of Speech
Countable and Uncountable Nouns
What is a Verb?
Flying the Hyper Skies
Ready, unplug, drive
Seen on the Science Fair Scene
Polar Ice Feels the Heat
Earth's Poles in Peril
Either Martians or Mars has gas
Add your Article


Nematodes (Phylum Nematoda from Gr. nema, nematos "thread" + ode "like") are one of the most common phyla of animals, with over 20,000 different described species (over 15,000 are parasitic). They are ubiquitous in freshwater, marine, and terrestrial environments, where they often outnumber other animals in both individual and species counts, and are found in locations as diverse as Antarctica and oceanic trenches. Further, there are a great many parasitic forms, including pathogens in most plants and animals, humans included. Only the Arthropoda are more diverse. Roundworms are triploblastic protostomes with a complete digestive system. Roundworms have no circulatory or respiratory systems so they use diffusion to breathe and for circulation of substances around their body. They are thin and are round in cross section, though they are actually bilaterally symmetric. Nematodes are one of the simplest animal groups to have a complete digestive system, with a separate orifice for food intake and waste excretion, a pattern followed by all subsequent, more complex animals. The mouth is often surrounded by various flaps or projections used in feeding and sensation. The portion of the body past the anus or cloaca is called the "tail." The epidermis secretes a layered cuticle made of keratin that protects the body from drying out, from digestive juices, or from other harsh environments, as well as in some forms sporting projections such as cilia that aid in locomotion. Although this cuticle allows movement and shape changes via a hydrostatic skeletal system, it is very inelastic so does not allow the volume of the worm to increase. Therefore, as the worm grows, it has to moult and form new cuticles. Most free-living nematodes are microscopic, though a few parasitic forms can grow to several meters in length. There are no circular muscles, so the body can only undulate from side to side. Contact with solid objects is necessary for locomotion; its thrashing motions vary from mostly to completely ineffective at swimming. Roundworms generally eat bacteria, algae, fungi and protozoans, although some are filter feeders. Excretion is through a separate excretory pore. Reproduction is usually sexual. Males are usually smaller than females (often very much smaller) and often have a characteristically bent tail for holding the female for copulation. During copulation, one or more chitinized spicules move out of the cloaca and are inserted into genital pore of the female. Amoeboid sperm crawl along the spicule into the female worm. Eggs may be embryonated or unembryonated when passed by the female, meaning that their fertilized eggs may not yet be developed. In free-living roundworms, the eggs hatch into larva, which eventually grow into adults; in parasitic roundworms, the life cycle is often much more complicated. Roundworms have a simple nervous system, with a main nerve cord running along the ventral side. Sensory structures at the anterior end are called amphids, while sensory structures at the posterior end are called phasmids. Parasitic forms often have quite complicated life cycles, moving between several different hosts or locations in the host's body. Infection occurs variously by eating uncooked meat with larvae in it, by entrance into unprotected cuts or directly through the skin, by transfer via blood-sucking insects, and so forth. Nematodes commonly parasitic on humans include whipworms, hookworms, pinworms, ascarids, and filarids. The species Trichinella spiralis, commonly known as the trichina worm, occurs in rats, pigs, and humans, and is responsible for the disease trichinosis. Baylisascaris usually infests wild animals but can be deadly to humans as well. Haemonchus contortus is one of the most abundant infectious agents in sheep around the world, causing great economic damage to sheep farms. In contrast, entomopathogenic nematodes parasitize insects and are considered by humans to be beneficial. One form of nematode is entirely dependent upon the wasps which are the sole source of fig fertilization. They prey upon the wasps, riding them from the ripe fig of the wasp's birth to the fig flower of its death, where they kill the wasp, and their offspring await the birth of the next generation of wasps as the fig ripens.

Designed and Powered by™