invertebrates, worms, flatworms, Turbellaria, planarians, Dugesia, Ottawa, ecology, environment, Rideau River, nature, natural sciences, Rideau River Biodiversity Project, Canadian Museum of Nature
|A flatworm of the genus Dugesia.
Its pharynx is extended out its body to catch prey. Two eyes on the
animal's head are visible in the upper left corner of the photo.
Class: Turbellaria - Turbellarians (Flatworms)
Order: Tricladida - Triclads
Family: Planariidae - Planarians
Characteristics of the family:
These worms are elongated and flattened, much like leeches. Flatworms
are both predators and scavengers.
The mouth is located on the bottom or underneath surface. Almost all species
are hermaphroditic, which means they have both male and female sexual
Flatworms can also reproduce by splitting in half (fission). The missing
body parts regenerate. Because of this peculiarity, flatworms in this
family are commonly studied in laboratories.
and tapered at both ends with eye spots (these are true but
crude eyes) on the head. Range of colouration is of gray, brown,
black and patterns of spots, stripes or mottling. Single opening
on ventral surface that acts as both mouth and anus.
||5 to 30 mm
||Found mostly east
of the Great Plains.
||Flatworms in this
class are photonegative (they avoid light) and are found under
rocks and debris during the day. Unlike most flatworms, those
in this class live in freshwater aquatic systems such as ponds,
lakes, ditches, rivers and streams.
||Flatworms are predators
and scavengers. Their mouth is located ventrally (on their belly).
The pharynx is extruded to swallow whole or bite a chunk of
their prey, which includes snails, worms or soft insect larvae.
||Can reproduce asexually
by fission, in which the animal splits in half and then regenerates
the missing body parts. Sexual reproduction between a pair of
hermaphroditic flatworms results in a few eggs being laid in