Class Turbellaria(flatworms)

Order Acoela
Order Rhabdocoela
Order Catenulida
Order Macrostomida
Order Nemertodermatida
Order Lecithoepitheliata
Order Polycladida
Order Prolecithophora
Order Proseriata
Order Tricladida
Family Bdellouridae--Bdelloura
Family Planariidae--Planaria

Major Attributes:

  1. True bilateral symmetry.
  2. Dorso-ventral flattening of the body.
  3. Unsegmented.
  4. Ciliated epidermis.
  5. System of sheathed nerve fibers.
  6. Parenchyma between the epidermis and the gastrodermis.
  7. Some cephalization.
  8. Blind ending gut.
  9. Flame cells for excretion.

Turbellarians are mainly free-living and aquatic, but some are terrestial and live in moist, humid environments. They range in size from a few millimeters to a half meter long. Small turbellarians use cilia for their propulsive force, and some very small forms swim through fluid. A lot of energy is used for the production of mucus to lubricate and protect the surface of the body and to help capture prey. Flatworms have several muscle layers of circular, longitudinal, diagonal and transverse fibers. Most are hermaphroditic and reproduce sexually, but assexual reproduction by fission is also possible. They are also capable of regeneration.

Some Interesting Facts:

Some Pertinent Books Found in Lamson Library:

  1. Buchsbaum, Ralph. 1976. Animals Without Backbones. Chicago: University of Chicago Press.
  2. Pennak, Robert W. 1964. Collegiate Dictionary of Zoology.New York: Ronald Press Company.


Preserved Material:

  1. Planaria--whole mount and typical cross sections
  2. Bdelloura--whole mount

Suggested Drawings:

(Susan A. Bergeron) (Edited by Betty Miller, Spring 1995)