FlatwormsRoundworms

Segmented worms

Worms!

Types of WormsFlatworms (Phylum Platyhelminthes)

Class Turbellaria (Planeria) Class Trematoda and Monogenea (Flukes)Class Cestoda (Tapeworms)

Roundworms (Phylum Nematoda and Rotifera)AscarisHookwormsTrichinellaPinwormsFilarial worms

Segmented worms (Phylum Annelida)Class Oligochaeta (Earthworms)Class Hirundea (Leeches)

Flatworms: Phylum PlatyhelminthesFlatworms are the simplest creatures with

bilateral symmetery.They develop from three germ layers.They do not have a hollow body cavity.Because they are flat, they can exchange oxygen

and CO2 with the environment through diffusion.They have no circulatory or respiratory

systems. They have an incomplete digestive system

consisting of a gut with a single opening.Nerves and sensory organs are located at one

end. This is known as cephalization. Many flatworms are parasites, living on or in

other creatures. Some are not and are found in freshwaters, marine, and terrestrial environments.

Flatworms: Phylum PlatyhelminthesClass Turbellaria:

Includes the Planarians, such as Dugesia species.Feed by scavenging bits of decaying plant and

animal matter.Food is ingested through a muscular tube which is

extended out from the body.How do they get ride of excess water?

Flame cells draw in excess water; water is transport through tubules and excreted through pores.

What are the cerebral ganglia, and what do they do?Simple brain; respond to stimuli and transmit signals

to musclesDescribe two way Planarians reproduce:

SexuallyFertilize each other and lay eggs on rocks or debris

Asexually Worms splits in two by attaching to solid surface

Flatworms: Phylum PlatyhelminthesPlanaria

Flatworms: Phylum PlatyhelminthesClass Trematoda and Monogenea

Consists of parasitic flukes.They can live in the blood, intestines, lungs, liver, or

other organs and are called endoparasites.Ones that live on the outside of their host are called

ectoparasites.How does a fluke stick to its host and what else does

this structure do?Anterior sucker and ventral sucker

Most flukes are hermaphroditic and have a complex life cycle that involves more than one host.

Once disease caused by flukes includes Schistosomiasis which affects more than 200 million people each year in Asia, Africa, and South America.

Flatworms: Phylum Platyhelminthes

Flatworms: Phylum PlatyhelminthesClass Cestoda

Also known as tapeworms, which can live in the intestines of almost all vertebrates.

At the anterior end is a structure known as the scolex. What is its structure and function?Has hooks and suckers that enable the worm to attach

to its host.Behind the scolex are the body segments called

proglottids.What happens to these during reproduction?

They grow in length; become fertilized from another either from same individual or another individual.

How can a human become infected with a taperworm?When they eat undercooked beef

Flatworms: Phylum PlatyhelminthesTapeworm

Roundworms: Phylum Nematoda and Rotifera Roundworms have bilaterally symmetrical

bodies and a fluid filled space to store eggs and sperm and for support.

They have a complete digestive system, that is, one with two openings, unlike cnidarians, ctenophores, and flatworms.

They have separate sexes. The vast majority are free-living on on land and in the water, and are parasites of plants and animals.

Roundworms: Phylum Nematoda and Rotifera Ascaris

Live in intestines of humans as larvae, then move to bloodstream and are carried to lungs and throat can block air passages and cause bleeding.

HookwormsGo through feet and travel through blood to lungs and

throatIf ingested, they will move to intestines and develop into

adults Trichinella

Live in intestines; larvale travel through blood stream to muscles and form cysts, causing muscle pain and stiffness (trichinosis)

PinwormsLive in intestines; tiny white threads in the lower

intestines; females come out at night and lay eggs on anus which spreads via scratching.

Filarial wormsElephantitis infects lymphatic system and is spread by

mosquito

Roundworms: Phylum Nematoda Ascaris

Roundworms : Phylum Nematoda Hookworms

Roundworms : Phylum Nematoda Trichinella

Roundworms : Phylum NematodaPinworms

Roundworms : Phylum NematodaFilarial worms

Segmented worms: Phylum AnnelidaFeather-duster worms, common earthworms

and leeches, are all members of this phylum. The phylum name means little rings. These organisms are bilaterally symmetrical

and, like mollusks, have a true coelom, a complete internal body tube

What does this structure allow to happen when the organism moves?It allows the body to contract.

Most have external bristles called setae.All organ systems are well-developed.

Segmented worms: Phylum Annelida Class Oligochaeta:

The most familiar members of this class is the earthworm. Describe how it moves (and the structures involved):

Thay have a fluid skeleton, and to move forward, they squeeze circular muscles of each segment, to extend their body.

They use their rough bristles to grip the surface of the ground at the front, then use longitudinal muscles to pull their ends up to meet the front

Complete or incomplete digestive tract? Explain. Complete two openings and one-way

Open or closed circulatory system? Explain. Closedvia two main blood vessels, dorsal and ventral

Oxygen and CO2 diffuse directly through the skin. The nervous system consists of a chain of ganglia connected by a

ventral nerve cord. How do earthworms reproduce? Be sure to mention any special

structures and their functions Two press their ventral surfaces together with anterior ends pointing

in opposite directions They are held be setae and clitellum Exchange sperm with each other, ideally fertilizing each other (they

are hermaphodites!)

Segmented worms: Phylum Annelida- Earthworms

Segmented worms: Phylum AnnelidaClass Hirudinea

Consists of about 500 species of leeches.They have no setae. At each end is a sucker

that can attach to surfaces.What two things do they secrete when they

suck blood?AnaestheticA substance that prevents blood from clotting

Segmented worms: Phylum Annelida- Leeches