Download Chapter 3, Section 1 – Protists

Chapter 1, Section 4 – Worms
I.
Characteristics of Worms
a. Classified into three phyla:
i. Flatworms (Playhelminthes)
ii. Roundworms (Nematoda)
iii. segmented worms (Annelida)
b. not all worms fit one particular description
II.
Body Structure
a. invertebrates
b. long, narrow body without legs
c. bilateral symmetry
d. have head and tail ends
e. all have tissues, organs, and body systems
III.
Nervous System
a. Simplest organisms with brain
b. Brain is a knot of nerve tissue in the head end
c. Some sense organs are located in head end to detect objects, food, mates,
and predators
IV.
Reproduction
a. Both sexual and asexual reproduction
i. Some species have separate sexes (male and female)
ii. some individuals have both male and female sex organs
1. these worms do not usually fertilize themselves!
iii. asexual reproduction – breaking into pieces
V.
Flatworms
a. Characteristics that all flatworms share
i. Flat body structure
ii. Soft like jelly
b. Many are parasitic
i. Includes all tapeworms and flukes
c. Planarians – free living flatworms
i. Are scavengers, but also prey on animals smaller than themselves
ii. Obtaining food:
1. planarian glides over food and inserts feeding tube
2. digestive chemicals begin to break down food
3. planarian sucks up partly digested material
4. digestion is completed inside body cavity
5. undigested food is expelled through feeding tube
d. Tapeworms – parasitic flatworms
i. Adapted to absorbing food from the host’s digestive system
ii. Can live in more than one host during lifetime
iii. Life cycle of tapeworm p.29 (Figure 22)
Chapter 1, Section 4 – Worms
VI.
Roundworms
a. Live in any most environment – soils, sands, pools of hot water
b. Some are free-living while others are parasites
c. very small and difficult to see
d. cylinder-shaped body
e. have an one-way digestive system
i. food enters mouth
ii. wastes exit through anus
VII.
Segmented Worms
a. Examples: earthworms, leeches, and sea-floor worms
b. Have bodies made up of linked sections called segments
c. Some organs are repeated in the segments
i. Example: each segment has tubes for waste removal
ii. Reproductive organs are found only in specific segments
d. have a nerve cord and digestive system (one-way) that run the length of the
worm
e. Closed Circulatory system:
i. Blood moves only within a network of connected blood vessels
ii. Blood carries food and oxygen to cells
iii. Closed system moves blood more quickly than an open system
f. tunnel for living
g. earthworm obtains oxygen through it’s skin
h. consumes leaves and decaying matter
i. helpful for soil fertility