PYLUM: Platyhelminthes

• What is the phylum of flatworms?

  Platyhelminthes
• What is the primary adaptation of the endoderm in flatworms?

  It is adapted for digestion and absorption of nutrients.
• How are Platyhelminthes characterized in terms of body shape?

  They have flat bodies that are flattened dorsoventrally.
• What distinguishes free-living species of Platyhelminthes from parasitic species?

  Free-living species live in water, while parasitic species live within the body of a host.
• Give an example of a free-living species of Platyhelminthes.

  Planaria
• What is an example of a parasitic species of Platyhelminthes?

  Bilharzia parasites
• What level of organization do Platyhelminthes exhibit?

  They have an organ level of organization.
• What are the three germ layers in Platyhelminthes?

  Ectoderm, endoderm, and mesoderm.
• What does the ectoderm develop into in Platyhelminthes?

  The outer protective layer (epidermis), nervous system, and excretory organs.
• What role does the endoderm play in Platyhelminthes?

  It forms the lining of the digestive tract and is involved in digestion and absorption.
• What does the mesoderm form in Platyhelminthes?

  It forms parenchyma cells that fill the space between the digestive tract and the epidermis.
• What is the body cavity status of Platyhelminthes?

  They are acoelomate, meaning they have no coelom.
• Where do the internal organs of Platyhelminthes occur?

  In the parenchyma of the mesoderm.
• What is cephalisation in Platyhelminthes?

  It is the concentration of nerves and sensory organs at the anterior end (head).