ANNELIDABy Emily Chu and Wonhyoung Kim

http://surferjerry.com/wp-content/uploads/2009/02/giant-south-african-earthworm.png

Segmented worms

CLASSES Oligochaeta (earthworms and relatives)

Polychaeta (polychaetes)

Hirudinea (leeches)

http://www.microteufel.com/TripReports/Maui/Aquarium/IMG_0063s.jpg

http://www.cheshirewildlifetrust.co.uk/IMAGES/watch_earthworm.jpg

http://www.io.com/~dierdorf/leech.jpg

Earthworm

Christmas tree worm

Leech

BODY CAVITY (COELOM) Present

Annelida=coelomate (has a true coelom)

http://biology.unm.edu/ccouncil/Biology_203/Images/SimpleAnimals/Coelomate.JPG

BODY SYMMETRY Bilateral symmetry

http://www.mun.ca/biology/scarr/142003_Annelida.jpg

Have brain-like pair of cerebral ganglia Ventral nerve cords with segmental ganglia

(runs through length of body)

NERVOUS SYSTEM

CIRCULATORY SYSTEM Closed circulatory system—blood contained

within vessels

Blood contains oxygen-carrying hemoglobin

DIGESTIVE SYSTEM Earthworms eat through the soil, extracting

nutrients as the soil passes through the alimentary canal.

Have digestive tract

http://johnson.emcs.net/life/images/earthworm.jpg

EXCRETORY SYSTEM Metanephridium=excretory tubes

Remove waste from the blood and coelomic fluid through exterior pores

Nephrostomes=ciliated funnels

LOCOMOTION/MUSCULATURE Chaetae=bristles that provide traction for

burrowing Each segment is surrounded by a longitudinal

muscle, which is in turn surrounded by circular muscle.

Contractions of these muscles allow for movement.

http://oceanexplorer.noaa.gov/explorations/03windows/logs/jul28/media/naut_allseate_600.jpg

SKELETAL TYPE No true skeleton Hydrostatic skeleton—controlled by coelomic

fluid

SENSORY STRUCTURES/FEATURES

Simple sensory structures Single-celled structures detect light,

chemicals, pressure waves, and contact

Some polychaetes have ocelli (“little eyes”)

REPRODUCTION Hermaphrodites Earthworms cross-fertilize

Two earthworms exchange sperm then separate Received sperm are stored temporarily while the

clitellum secretes a mucous cocoon Cocoon slides along the worm, picking up eggs

and then the stored sperm Some earthworms can also reproduce

asexually by fragmentation followed by regeneration

Clitellum

http://static.howstuffworks.com/gif/willow/earthworm-info0.gif

GAS EXCHANGE

SKIN! This is the respiratory organ.

Hemoglobin in blood carries oxygen

Some polychaetes have gills

http://upload.wikimedia.org/wikipedia/commons/e/ea/Christmas_tree_worms.jpg

OTHER UNIQUE FEATURES Today, leeches are used to drain blood that

accumulate in tissues following certain injuries.

Leeches secrete hirudin (prevents blood from clotting, which allows leech to feed)

Hirudin has the potential to be used in the future to dissolve blood clots that form during surgery or as a result of heart disease.

THE END!!!!

Just kidding…

http://www.breaktaker.com/albums/pictures/animals/LaughingCat.jpg

QUIZ TIME!1. What is the primary respiratory organ?

2. Describe the annelid’s circulatory system.

3. Give two examples of methods of reproduction and explain each.

4. Which of these phyla consists of species with a coelom?

A. PoriferaB. CnidariaC. AnnelidaD. Platyhelminthes

CHECK YOUR ANSWERS!1. The skin

2. Closed circulatory system

3. Sexual—two hermaphroditic annelids align and exchange spermclitellum secretes cocoon Asexual—fragmentation and regeneration

4. C. Annelida