Ch. 13

What phylum do flatworms belong to?

Phylum 3 – Platyhelminthes

Name two examples of organisms found in the Platyhelminthes phylum.

Planarians and Tapeworms

What type of body structure do flatworms have?

Soft, wormlike bodies that are flattened and elongated.

How many tissue layers do flatworms possess?

Three tissue layers: endoderm, mesoderm, and ectoderm.

What type of symmetry do flatworms exhibit?

Bilateral symmetry.

What is cephalization in flatworms?

The presence of a head with sensory structures to detect and respond to the environment.

What major organ systems are present in flatworms?

Digestive, Respiratory, Excretory, Nervous, and Muscle systems.

Are most flatworms parasitic or free living?

Most are parasitic, living in a host animal.

What class do planarians belong to?

Class – Turbellaria.

Where is the mouth of a planarian located?

On the ventral surface at the end of the pharynx.

What type of digestive system do planarians have?

An incomplete digestive system with no anus.

What is the movement mechanism of planarians?

They glide through water using cilia and muscle contractions.

What are the eyespots of planarians sensitive to?

Light, as they are photosensitive.

What do planarians typically eat?

They are scavengers that eat dead organic matter.

How are nutrients distributed in the body of flatworms?

Nutrients are diffused directly into body tissues from the digestive system.

Where are planarians typically found?

On the underside of rocks, leaves, sticks, or submerged in lakes, ponds, and streams.