1. The Invertebrates
The Worms

2. pork Tapeworms life cycle
each proglottid can produce, fertilize and store eggs
could be 1000s of eggs inside each proglottid
pigs (intermediate host) eat proglottids and eggs hatch inside pig’s intestines
larva burrow to the muscles of the pig
larva form cysts that contain a scolex
person eats improperly cooked pork, the scolex emerges and attaches to the intestine so that the proglottids can grow
proglottid breaks off and released when person defecates
pigs eat feces and process starts again

3. Pork Tapeworm Life Cycle

4. Other Tapeworms beef tapeworm fish tapeworm
most common because man prefers rawer beef than pork
fish tapeworm
largest, can grow up to 18m long

5. Phylum Nematoda
the roundworms

6. Phylum Nematoda tiny, cylindrical, usually less than 2.5 cm
inhabit virtually every environment (hot, cold, dirt, humans, acidic)
highly selective on where they live so humans do not have to fear most parasitic roundworms
separate male and female roundworms
round & unsegmented
longitudinal muscles only

7. Ascaris (Read pages )
an intestinal roundworm which can harm its host if the person is sensitive to the chemicals the worm produces
large compared to most roundworms, up to 30cm
epidermis secretes a thick cuticle for support and protections from host’s digestive enzymes
2 openings
one for ingestion at the anterior end
one for excretions at the posterior end
inner tube is the digestive canal

8. Ascaris (Read pages 357-358) a human intestinal parasite
“a tube within a tube”
only reproduces sexually
not hermaphroditic
intestine
cuticle
mouth
anus

9. Phylum Annelida
“little rings”
the segmented worms

10. Segmented worms segmented externally and internally
each external segment is separated internally by a septum
most live in salt water, but there are some freshwater and soil worms
“tube within a tube” body plan
outer – muscle and skin (body wall)
inner – digestive tract
closed circulatory system

11. Class Oligochaeta “the earthworm” (life process chart)
the most familiar of the segmented worms
segments are numbered from the anterior to the posterior end
segments have a large swelling covering them known as the clitellum

12. Class Oligochaeta “the earthworm”
Movement
externally you can see setae
tiny bristles on the ventral and lateral surface of the body
four pairs on each segment
two muscle layers to help with movement
circular layer to lengthen and thin the worm
longitudinal layer to shorten and thicken the worm

13. Class Oligochaeta “the earthworm”
Nutrition
eats vegetation, refuse, and decayed organic matter
order of the digestive tract:
mouth – found on ventral surface of the first segment
pharynx – muscular structure for drawing in food
esophagus – carries food to the crop
crop – stores food temporarily
gizzard – grinds the food
intestine – digestion of the food
anus – exit point

14. Class Oligochaeta “the earthworm”
Circulation
has a closed circulatory system
blood will absorb nutrients and oxygen from the digestive tract and respiratory structures and carry them to tissues all throughout the body
accomplished by two vessels and one accessory vessel
dorsal blood vessel – carries blood to the anterior part of the body
ventral blood vessel – carries blood to the posterior part of the body
aortic arches (5) – surround the esophagus and connects the dorsal and ventral blood vessels

15. Earthworms
dorsal blood vessel
aortic arches
ventral blood vessel

16. Class Oligochaeta “the earthworm”
Respiration
the small vessels off of the dorsal and ventral vessels come near to the epidermis and then oxygen and carbon dioxide diffuse across the epidermis
the earthworm must be kept moist to accomplish this

17. Class Oligochaeta “the earthworm”
Excretion
nephridia
tubelike structures found in pairs in every segment except the first three and the last
it absorbs waste from the blood and excretes it out of the pores, known as nephridiospores, in the worm’s side

18. Class Oligochaeta “the earthworm”
Nervous system
ganglia
mass of nerve tissue found above and below the pharynx
a ventral nerve cord extends the length of the body
sensitive to light, touch, and certain chemicals
Reproduction
earthworms are hermaphroditic
read pages

19. Class Hirudinea “the leeches”
has anterior and posterior suckers
there is no head or clitellum present
many feed on blood
can consume several times their own weight in blood and they need several months to digest one meal