- 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
- True bilateral symmetry.
- Dorso-ventral flattening of the body.
- Ciliated epidermis.
- System of sheathed nerve fibers.
- Parenchyma between the epidermis and the gastrodermis.
- Some cephalization.
- Blind ending gut.
- 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:
- If a flatworm is starved it is capable of shrinking to hatching size
and when fed it has the ability to grow back to original size.
- Temnocephalidae are ectoparasites on the body surfaces of some crustaceans.
They have an adhesive disc and tentacles, but lack cilia.
Some Pertinent Books Found in Lamson Library:
- Buchsbaum, Ralph. 1976. Animals Without Backbones. Chicago:
University of Chicago Press.
- Pennak, Robert W. 1964. Collegiate Dictionary of Zoology.New
York: Ronald Press Company.
- Planaria--whole mount and typical cross sections
- Bdelloura--whole mount
- Draw a planarian (wholemount) along the left side of the page and at
proper locations, draw cross-sections of what the body looks like at that
location. Try to picture in your mind what the sections in between would
- Draw an enlarged section of the area of the nerve material, the ventral
epithelium and the mucuous glands in the epithelium. Can you see any nerve
cell bodies in the nervous tissue. Can you see any cilia? What are the
relationships between the three germ layers in the section you drew?
- How does the whole mount of Bdelloura compare to the whole mount
(Susan A. Bergeron) (Edited by Betty Miller, Spring 1995)