Download 3 Phyla of Worms – Notes - Effingham County Schools

3 Phyla of Worms – Notes
Common
 A long, thin invertebrate with BILATERAL symmetry, a nervous system, and
Characteristics
cephalization
of All Worms  Simplest animal to have a true organs like a brain!
 Reproduction - Sexual (hermaphroditic – male and female reproductive organs)
First with
and Asexual – Fission (breaking into pieces)
Organ Systems!  Many are parasites- (good/bad relationship) live on or in a host
Three Phyla
Characteristics
of Flatworms
A. Platyhelminthes (flatworms)
B. Nematoda (roundworms)
C. Annelida (segmented worms)
A. Soft flattened worms with true tissues and internal organs.
B. Simplest animals to have bilateral symmetry and cephalization.
1. Feeding – some carnivorous, most parasitic; one opening into gut; pharynx sucks
in food and releases waste
2. Respiration/ Circulation/ Excretion – No respiratory No circulatory system,
system; Obtain nutrients and oxygen by diffusion directly into cells. Simple excretory
system of specialized cells.
3. Response/Movement – ganglia= groups of nerves in head control nervous system
(like a brain); “ladder” of nerves run over body; eyespot detects light; move by cilia
and squirming using outer layer of muscle tissue
Diseases caused
by Flatworms
A. Flukes-Usually infect internal organs of host – Example: The blood fluke
Schistosoma- causes tissue damage that could result in death
B. Tapeworms – Long, flat, and have adaptations for life inside intestines of host
Characteristics
of Roundworms
A. Body plan- First animals to have a one way digestive system with mouth and
anus (tube within in a tube);
B. First animals to have a fluid filled body cavity called a pseudocoelom- “false body
cavity”
1. Feeding- many are carnivores with grasping mouthparts, some herbivores, many
are parasites
2. Respiration/Circulation/ Excretion- No Respiratory or Circulatory Systems; rely
on diffusion. Simple excretory organs.
3. Response/movement -have ganglia (brain) and simple nervous system, have
muscular system and move like snakes
Diseases caused
by
Roundworms
Characteristics
of Segmented
worms
A. Trichinella causes painful cysts in the muscle tissue of humans and other animalstransmitted by eating undercooked meat containing worm eggs
B. Filarial worms cause Elephantiasis- fluid buildup that causes abnormally large
limbs – transmitted through the bite of insects like mosquitos
C. Ascarids cause malnutrition in humans, horses, cows, etc by filling the intestinal
tract of its host and absorbing all nutrients
D. Hookworms attach to the lungs and intestines and suck blood – common in
humans(1/4 of world population); larvae pierce the skin & burrow into the body. Can
severely damage internal organs. Transmitted through humans’ and other animals’
waste. (Wear Shoes!)
A. Body Plan- tube within a tube, digestive system with mouth and anus; body
divided into sections called septa that are specialized for different functions. First
animals to have true circulatory system and coelom – body cavity.
1. Feeding- predators to filter feeders; use pharynx to get food, stored in crop, ground
up in gizzard, absorbed in intestine.
2. Circulation/ Respiration/ Excretion- closed circulatory system with vessels; breath
through gills or through skin; have excretory organs called nephridia
3. Response/Movement- have ganglia in each segment of the head, nervous system;
move by contracting and relaxing muscles
Intestine
Clitellum
Gizzard
Anus
Dorsal blood vessel
Aortic
Crop
arches
Brain
Esophagus
Ventral Blood Vessel
Mouth
Ecology of
Segmented
Worms
Pharynx
Ventral Nerve Cord
Segments
A. Aerate, mix, and fertilize the soil- have created some of the most fertile soils
on earth!
B. Tunnels provide passage ways for plant roots and water
C. Important in the diets of many other animals such as birds, toads and snakes;
marine annelids important in the diets of fishes, crabs, and lobsters