Download worm notes - Mahtomedi Middle School

WORM
NOTES
Chapter 9, section 4
Are grouped into
Body Structure:
 Invertebrates
 Long
narrow bodies with no legs
 Tissue, organs and body
systems
 Bilateral symmetry
 Have head and tail ends
b. Nervous system
i. Simplest organisms with a brain
 sensory organs in its head end to respond
to vibrations, food, mates, and predators

c. Reproduction
i. sexually AND asexually
 ii. Some worms are hermaphrodites (both male and female)

Characteristics of Flatworms:
 Duh,
flat
bodies
 Examples
include
tapeworms
and
planarians
Parasites
 Lives
inside another organism
and takes its food from that
organism
 example: Tapeworms
Hosts

Organism that a parasite lives on or in
Does a parasite effect its host?




It sure does…
Abdominal pain, anorexia, weight loss, –
USUALLY asymptomatic!
Problems arise when the tapeworm becomes
too large and starts blocking the bowel or
robbing us of vital nutrients
Tapeworm cysts can take up valuable space. If
the cyst settles in the brain, eye or liver, normal
function of these organs may be severely
restricted.
Free-living organisms
 Organisms
that don’t live
in or on other
organisms
Free-living flatworms live:
 Live
in ponds
 Damp soil
 Oceans
Characteristics of Planarians

Phylum Platyhelminthes
 “platy”
means flat
Eyespots – to detect light
 Long feeding tubes that come out of their
“stomach” area
 Scavengers
 Predators – meat eaters
 Live in cold ponds and streams

How Planarians eat!
Extends feeding tube (pharynx) into food
source
 Releases digestive juices to break it down
 Sucks food in
 Undigested food exits through feeding
tube (pharynx)

A planarian eating a midge.
What about their eyesight?



They have eyespots only for detecting light.
Find food by other sensing organs in their head
area
(no need to write
this info down)
How Planarians reproduce

Sexually with eggs and sperm

Asexually by regeneration (growing body
pieces back)
 You
can cut the head off and it will grow back
Tapeworms:
Adult Tapeworm – each segment contains eggs
and sperm. When fertilized they break off and are
released with wastes (you know, poop).
Tapeworms

Body adapted to
absorbing already
digested food
 Have
a head
(Scolex) with hooks
and suckers
 No mouth or stomach
– no eyes either
hooks
Lifecycle of dog tapeworm:
 Dog
eats rabbit infected with
tapeworm larvae
 It attaches to the lining of the dog’s
digestive system.
 The attached tapeworm grows and
produces eggs/sperm. Fertilized
eggs leave the body with wastes.
Lifecycle, continued:
A
rabbit (or sheep or
whatever) eats grass covered
with the fertilized eggs and
becomes infected with
tapeworm larvae.
 Then it starts over…
ROUNDWORMS
a. General Characteristics


Belong to the phylum Nematoda
tiny and hard to see but may be most
abundant animals on earth
Body Structure



cylindrical bodies
pointed at each end
digestive system that is like a tube open
at both ends
 food travels in one direction from mouth
to anus
 more efficient
 allows animal’s body to absorb a
large amount of needed substances
in foods.
Types of roundworms




Ascaris
Hookworms
Trichinella
Heartworms
Roundworms, Continued
 EXAMPLE:
pet
Heartworm in your
Parasite examples
Examples of heartworms
Segmented Worms
Body Structure

body divided into segments
 outside segments look almost
identical
 inside there are many differences
 Many organs repeat
themselves
*each segment has tubes to
remove wastes
More about body structure



Reproductive organs in certain
sections only
Nerve cord & Digestive system
that runs length of worm’s body
two openings – mouth and
anus
Circulatory System

Closed circulatory system
 This is faster than an open
circulatory system (moves blood more
quickly)
5 pairs of hearts
Dorsal blood vessel – along back
Ventral blood vessel – along belly
Earthworms and the Environment


need moist soil because oxygen is
obtained through moisture on it’s skin
helpful to the environment
 loosen soil by tunneling allowing air,
water, and plant roots to move
through it
 make soil more fertile by their
droppings
What you will see inside:
Bring your notes to
class when we
dissect!!! Please note
diagrams on page 3;
they will be very
helpful!!!
V.
Questions to see if you understand
worms
a: Nematodes are more complex than
flatworms because…
 They
have a mouth and an
anus! Makes it more
efficient. Wow is that
complex!
b. What is the difference in
complexity between the
digestive systems of a flatworm
and a roundworm?
 Flatworm
is 2-way, roundworm
is 1-way since it has 2
openings
Change last question…
What are the phylum names for each?
Flatworms:
 Roundworms:
 Segmented worms:

ANSWERS:
Flatworms: Platyhelminthes
 Roundworms: Nematoda
 Segmented worms: Annelida

Circle the letter of each sentence
that is true about roundworms
C. Most roundworms are tiny and hard to
see
 D. Roundworms have a digestive system
that is like a tube, open at both ends

Wastes exit a roundworm’s
digestive system through an
opening called the…

anus
What is the advantage of a one
way digestive system?

Faster or more efficient
Circle the letter of each sentence
that is true about segmented
worms
B. Earthworms are a type of segmented
worm
 C. Segmented worms have bodies made
up of many linked sections

Earthworms have a digestive
system with ____ openings.

2
What is the advantage of a closed
circulatory system?

Blood moves faster
Circle the letter of each
characteristic of earthworms.
B. Make tunnels
 C. Get oxygen through the skin

How do earthworms improve the
soil?
Tunnels allow air, water, and plant roots to
move through
 Makes soil more fertile from wastes
