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BIOL 111 Study Guide - Final Guide: Blood Vessel, Nephridiopore, Gastrointestinal Tract


Department
Biology (Sci)
Course Code
BIOL 111
Professor
Suzanne Gray
Study Guide
Final

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Organism
Phylum Annelida Earthworms
Brief
Description
Daytime, remain underground to avoid drying out
Nighttime, come above ground to search for food and to mate
External
Anatomy
Thin transparent cuticle secreted by the epidermis to protect the worm
Mucus is also secreted from the glandular cells, aids in protection,
locomotion as well as respiration
The anterior end is thicker than the posterior end
The Clitellum is a thick band around the worm, found closer to the
anterior end
The ventral side is flatter and lighter than the dorsal side
Respiratory, digestive, circulatory and nervous systems are found in the
anterior end
Earth worm is divided into segments (each segment contains four pairs of
setae (bristle like projections that aid in anchoring the worm to the
substrate)
Segment 1: the mouth; thin ventral slit contains the peristomium
(fleshy lobe that surrounds the mouth and the protosmium (fleshly lobe
that proceeds the mouth)
Segment 9 to 10: contains the seminal receptacles, where the sperm is
stored
Segment 14: two female genital pores, where the egg is released
Segment 15: two male genital pores, where the sperm is released
Segment 26: genital setae is found here, secrete a sticky mucus-like
substance that allows the worms to stay together when undergoing
copulation
Segment 32-37: clitellum is found here, secretes a mucus cocoon in
which the sperm and egg are deposited
Last segment: the anus is found here
Movement
Move via the use of longitudinal and circular muscles (shortening and
lengthening)
1. Circular muscles contract
2. Putting pressure on the fluid in the coelom
3. Causes the worm to elongate
4. Longitudinal muscles contract
5. Causes the worm to shorten
6. Setae keep the worm anchored to the ground during this movement
Reproduction
Egg is produced in the ovaries and travels through the oviduct to the
female genital pore where the egg is then released
Sperm is produced in the semical vessels and travels through the vas
deferens to the male genital pore where the sperm is then released
Genital setae is produced in order for the worms to stay together during
copulation
Fertilization occurs externally
The Clitellium creates a mucus cocoon in which the sperm and egg are
deposited
The cocoon is left on the surface of the Earth, mucus disintergrates and
the cocoon begins to harden
In about a week, a worm is formed
Copulation takes about 2-3 hours
Circulatory
System
Dorsal (anterior) and ventral blood (posterior) vessel
Closed circulatory system; blood travels through the blood vessels
Dorsal blood vessel is larger than the ventral blood vessel
Five aortic arches which act as the main pumping organ
Pump blood towards the ventral blood vessel; blood then travels to the
capillary net, where dorsal branches then receive the blood and bring it
back to the dorsal blood vessel
One way-valve system in the dorsal blood vessel to prevent the back flow
of blood (not need in the ventral blood vessel because it has a pumping
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