Characteristic Pseudocoelomate/tube-within-a-tube
- Gut surrounded by a second (body) cavity (coelom)
- but not lined with mesoderm completely
- Tripoblastic
- Complete (one-way) digestive system
- Dioecious (two individuals/ two sexes)
Advantages of a coelom (Pseudocoelomates)
- more space for internal complecity
- greater surface area to support viscera
- flexibility
- hydrostatic support (water skeleton)
Phylum Nematoda
Roundworms
Characteristics (Phylum Nematoda)
- Freshwater, marine, soil, endoparasite (internal) = everywhere
- Carnivores, plant juices, saprophytes, or parasites
Unique Support System (Phylum Nematoda)
- Nonliving, external, elastic, through exterior = cuticle
- only longitudinal muscles, not circular
- fluid filled forms a hydrostatic skeleton
Hydrostatic Skeleton (Phylum Nematoda)
- Muscle contraction bends the cuticle on one side (shortening)
- force is transmitted by the body fluid, stretching the cuticle on another side (lengthening)
- Muscle on the first side relaxes; worm returns to the original position
*cuticle opposes the longitudinal muscles
Life Cycle (Phylum Nematoda)
- Egg shed with feces
- Ingested-plants, soil, hands
- Juveniles burrow from intestine to circulatory system
- carried to lungs, mature
- up bronchi/ trachea, swallowed to intestines
Symptoms (Phylum Nematoda)
- Usually none
- Abdominal pain
- Intestinal blockage
Control/ Prevention (Phylum Nematoda)
clean and cook plants
wash hands
Hookworms Life Cycle
- eggs pass in feces, hatch, feed on soil bacteria, penetrate skin to blood, then lungs, mature, on to intestine via throat
- rasp inside of large intestine, suck blood
Hookworms Symptoms
anemia, fatigue, can cause physical and mental retardation in children
Hookworm Prevention
wear shoes
Pinworms Life Cycle
- Adult females migrate from small intestine to anus to lay eggs
- resultant itch produces scratching and reinfection or infection via eggs on clothing
Pinworm Symptom
itching
Pinworm Control
Drugs
Trichinellas Life Cycle
- Ingestion of undercooked pork, bear meat
- larvae released, mature, live in small intestine, produces new larvae
- larvae eventually form cyst in muscle
Trichinellas Symptoms
nausea, vomiting, sweating, diarrhea, more serious complications
Trichinellas Prevention
cook meat
Filarial Worms
- Dog heart-worm (mosquito transmit)
- Elephantiasis (swelling in lymph system)
Helminth Worms
General term used to describe worm-like animals that are parasites
Example: tapeworms, flukes, roundworms,
-not segmented worms nor leeches
