1. Explain the circulatory system of Mollusks
Bell Ringer
Explain the circulatory system of Mollusks

2. Annelida

3. Annelida Segmented worms True coelomates ~15,000 species
Including earthworms, freshwater worms, leeches
2/3 of the phylum are marine worms
Clam worms, plumed worms, parchment worms, scaleworms, lugworms, etc
True coelomates

4. Annelida Highly developed group Sometimes called “bristle worms”
Nervous system is more centralized
Circulatory system more complex
Sometimes called “bristle worms”
Setae – tiny chitinous bristles
help anchor segments during locomotion
Aid aquatic forms in swimming
Stiff setae prevent worm from being pulled or washed out of its home

5. Ecological Relationship/Economic Importance
Distributed worldwide
Sea, fresh water, terrestrial soil
Many are predators
Indirect economic importance
Prey to other organisms
Fish bait
Earthworms increase drainage & aeration of soils
Help mix the soil & distribute organic matter
Medical uses for leeches

6. Body Plan Two-part head Series of Segments Pygidium Prostomium
Peristomium
Series of Segments
Pygidium
Posterior portion – bearing the anus

7. Prostomium

8. Body Plan
Coelom
serves as a hydrostatic skeleton
Except in leeches
Annelid body has a thin nonchitinous cuticle surrounding the epidermis
epidermis surrounds circular muscles
circular muscles surround longitudinal muscles
longitudinal muscles surround the coelom
digestive system runs the length of body, perforating each septum
longitudinal dorsal and ventral blood vessels and ventral nerve cord follow the same path

10. Annelida Three Classes Polychaeta Oligochaeta (earthworms)
Poly=many; chaite=long hair/bristles
Oligochaeta (earthworms)
Oligos=few; chait-long hair/bristles
Hirudinea (leeches)

11. Class Polychaeta Largest class Mostly marine Most between 5 to 10 cm
more than 10,000 species
Mostly marine
Most between 5 to 10 cm
some less than 1 mm, others greater than 3 m
Live under rocks, in coral crevices, in abandon shells, burrow into sand or mud, or build their own tubes on submerged objects

12. Class Polychaeta Differ from other annelids Possess many setae
Have a well-differentiated head with specialized sense organs and paddle-like parapodia on most segments
Possess many setae
Do not have permanent sex organs, possess no ducts for their sex cells, and usually have separate sexes
Gonads appear as temporary swellings in the peritoneum & shed their gametes into the coelom
Some free-living, active burrowers; some sedentary living in tubes or burrows

14. Class Oligochaeta Over 3,000 species in a variety of habitats Setae
Most terrestrial or freshwater forms, some parasitic , few marine or brackish water
Setae
Long or short
Straight or curved
Blunt or needlelike
Arranged singly or in bundles
Aquatic forms have longer setae than earthworms

15. Earthworms “night crawlers” Burrow in moist, rich soil
Emerge at night to feed on surface vegetation & to breed
Rainy weather – stay near the surface
Dry weather may burrow several feet underground
Tropical earthworms
segments
Grow 3-4 meters in length

16. Earthworms Double transport system Peristaltic movement
Coelomic fluid & circulatory system
Food, waste, respiratory gases are carried by both
Closed circulatory system
Peristaltic movement
contraction of circular muscles lengthen body
contraction of longitudinal muscles shorten body

18. Digestive System
consists of the pharynx, the esophagus, the crop, the intestine and the gizzard.
Food is swallowed by the pharynx
passes through the esophagus
moves into the crop where it is stored
eventually moves into the gizzard
gizzard uses stones that the earthworm eats to grind the food completely
moves into the intestines releasing fluids to aid in the digestion

19. Earthworms Circulatory System closed circulatory system
circulates blood exclusively through vessels
three main vessels: aortic arches, dorsal blood vessels, and ventral blood vessels.
aortic arches function like a human heart.
dorsal blood vessels carry blood to the front of the earthworm’s body.
ventral blood vessels carry blood to the back of the earthworm’s body.

21. Earthworms Respiratory System do not have lungs
breathe through their skin by diffusion
For diffusion to occur, skin must be kept moist
Body fluid and mucous is released to keep its skin moist. Earthworms therefore, need to be in damp or moist soil.
They have tissue located at the head that is sensitive to light.
tissues enable an earthworm to detect light and not surface during the daytime where they could be affected by the sun.

22. Earthworms Reproduction Earthworms are hermaphrodites Clitellum Cocoon
contain both male and female sex organs
Although earthworms are hermaphrodites, most need a mate to reproduce
Clitellum
Secretes mucus to hold worms together
Cocoon

23. Class Hirudinea Leeches
Over 500 species; predominantly freshwater habitats
2-6 cm in length
Some reach 20 cm
Usually flattened dorsoventrally

24. Class Hirudinea Form & Function Fixed number of segments
usually 35
Typically have both anterior & posterior sucker
No parapodia, no setae
Many live as carnivores, temporary parasites, permanent parasites
Muscular, protrusible proboscis
Tubeluar extension of the oral region
Three jaws armed with teeth

25. Class Hirudinea Hermaphroditic but cross-fertilize
Clitellum only evident during breeding season

26. Medicinal Leeches
used as tools in tissue grafts and reattachment surgery
they secrete anticoagulants to prevent blood clots and relieve pressure due to pooling blood
leech saliva has other therapeutic properties
saliva helps reestablish blood flow to reattached body parts by means of a vasodilator, provides a numbing anesthetic, and lessens the risk of infection due to an antibiotic.

27. Treating Diabetes

28. http://videos. howstuffworks

29. "I was in Austria doing a cleanse and part of the treatment was leech therapy. These aren't just swamp leeches though - we are talking about highly trained medical leeches. "These are not some low-level scavengers - we're talking high-level blood suckers."