Biology 11
Phylum Annelida: Segmented Worms
Name: _______________________
Date: ________________________
A. Annelid Characteristics (Ref. p. 468-469)
Annelids are considered more “advanced” or “complex” than either roundworms or
flatworms for 2 reasons: presence of coelom and segmentation
1. Presence of true coelom
•coelom (definition): a fluid-filled body ___________ completely surrounded by
__________
•coelom is important for 2 reasons:
a) it allows room for development of _________________________________________
•What is the peritoneum?
•What is the function of the peritoneum?
b) it allows the animal to have 2 sets of muscle tissue - 1 set around the ______________
and the other set around the __________________________________
•Why is it important that these 2 sets of muscles work independently of each
other?
•How is this different from the roundworm?
2. Segmentation
•segmentation (definition): __________________________________________________
•segmentation is important for 2 reasons:
a) animals can increase in size by ____________________________________________
b) different segments can adapt to
____________________________________________
B. Earthworms (Class ______________________) (Ref. p. 469 - 470)
1. Gas Exchange and Circulation
•gas exchange takes place by diffusion at the __________________, but unlike flatworms
and roundworms, earthworms have a fluid called ______________ that takes O2 to all the
cells of the worm’s body and carries CO2 from body cells to the ________________ where
it diffuses out
•what else does blood carry to cells? ____________________________________________
•what red protein is present in blood that allows it to carry much more O2?
______________
•the circulatory system of earthworms consists of blood, blood vessels, and 5 simple
_______
•give the functions of the following:
•hearts: ________________________________________________________________
•ventral blood vessel: __________________________________________________
•dorsal blood vessel: ___________________________________________________
2. Digestive System
•what food does the earthworm
consume?_________________________________________
•what is consumed along with the food? _________________________________________
•give the functions of the following structures/organs:
•pharynx: ________________________________________________________________
•esophagus: _____________________________________________________
•crop: __________________________________________________________
•gizzard: ________________________________________________________
•what is the function of the sand here?
•intestine: _______________________________________________________________
•anus: ___________________________________________________________________
•what are the expelled wastes called? _____________
•why are they beneficial? ___________________________________________________
3. Excretory System
•nitrogen wastes from the blood diffuse into structures called ____________________
•most segments have ______ nephridia
•nitrogen wastes are excreted __________________________________________________
4. Movement
•earthworms have ____ muscle layers in body wall - a ______________ layer and a
____________________ layer.
•movement achieved by coordinated _______________ & _______________ of these layers
•setae (definition): __________________________________________________________
•function of setae:
___________________________________________________________
5. Nervous System
•give the function of the following structures:
•brain : ___________________________________________________________________
•ventral nerve cord: ______________________________________________________
•ganglion (definition): ______________________________________________________
•what is the function of the ganglia?
•nerves in the epidermis detect
_________________________________________________
6. Reproduction (see diagram on next page)
•earthworms are _________________________
•what is the function of the clitellum?
Use the following diagram AND handout (Phylum Annelida: Life Cycle to complete the
following
notes.
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Sperm are produced in the ______________, eggs are produced in the _____________.
During fertilization worms line up, facing in ____________ directions
________________ from each worm pass to openings in the other’s body where they are
______________ stored in the ________________ ___________________
________________ secretes mucus that holds the worms together & provides a medium
for the movement of ___________________- worms separate
Later, clitellum forms a ______________ in which both ____________& ___________
are deposited as it slides forward- ________________ occurs in the clitellum
Clitellum slides off anterior end-hardens into a ________________ where eggs hatch and
juvenile worms emerge.
C. Leeches (Class Hirudinea) (p. 471 - 472)
•nonparasitic leeches feed on
___________________________________________________
•describe the adaptations of parasitic leeches
D. Marine worms (Class Polychaeta) (p. 472)
•describe how polychaetes are different from oligochaetes (like earthworms)
•where are polychaetes found?