Common Name: Freshwater Planarian
Scientific Name: Dugesia tigrina
Kingdom: Animalia
Phylum: Platyheminthes
Class: Turbellaria
Order: Tricladida
Family: Dugesiidae
Genus: Dugesia
Species: D. tigrina
Planaria is the common name of freshwater, non-parasitic flat worms found in may parts of North America and Europe. These flatworms are three to twelve millimeters long. The Dugesia Tigrina is brownish in color. Some of the worms have a stripe down their back. It has a large mouth in the middle of its body. The flatworms can regenerate lost body parts. If it is split into two parts, each part can become a whole worm.
The Dugesia Tigrina has two eye spots that can detect light. These are not real eyes that can see a lot. They have a three layered body made up of the ectoderm, mesoderm and endoderm. The Dugesia Tigrina lives under rocks, plants, and debris in clear freshwater ponds and springs. They do well in these habitats because they can find the food they eat, especially mosquito larvae. In freshwater, they also eat various invertebrates.
To hunt for food, they have to swing their heads from side to side so they can sense where the food is. The Dugesia Tigrina can be found anywhere there is enough fresh water for their primary food, mosquitoes, to breed in large numbers. They are not endangered or threatened. There numbers increase and decrease according to the mosquito population.
The planarians use asexual reproduction and split from side to side. To reproduce, a worm lays eggs and the babies hatch fro the egg capsules. The Dugesia Tigrina does not have any known predators. The worms hide under rocks during the day, to avoid danger and to keep cool. The Dugesia Tigrina is used for study in high school and college. It is used as a model for re-growth of cells in both humans and other animals. Many scientists study this regeneration of cells for scientific purposes.
Author: Harrison N
Published: 02/2008
Sources:
www.answers.com/topic/freshwater-planarian
http://en.wikipedia.org/wiki/Planaria
www.visualsunlimited.com/browse/vu315.vu315235.html
Photo Credit: http://www.neozoen-bodensee.de/neozoen/dugesia-tigrina