Light exposure on the regeneration of Dugesia dorotocephala
The objective of this experiment was to test the effect of light exposure on the regeneration of Dugesia dorotocephala. Dorotocephala is a species which belongs to the kingdom Animalia, class Turbellaria, order Seriata, these worms are classified in the suborder Tricladida based on the three main branches of their digestive system. They are further subdivided based upon ecological habitat. They come in freshwater, marine and terrestrial forms (Alvarado, Reddien). they belong to the family Planariidae and genus Dugesia. These creatures display bilateral symmetry and are classified as metazoans (eumetazoans). Dugesia are found in freshwater habitats in various regions of the world. They inhabit places in Africa, the Middle East, Europe, Asia and even parts of Australia. These small animals tend to be elongated with a triangular head. They possess a dorsal surface coated in shades of grey, black and brown, and a ventral which is a paler shade than the dorsal side. In general they are small and soft bodied which allows them to hide in tight spaces. They are classified as free living and lack a coelom, a hemal system and a circulatory system. Because of this many of their functions depend on diffusion. Freshwater turbellarians are benthic inhabitants of lakes, ponds, springs and streams. Their bodies are covered with cilia and they possess a syncytial epidermis. These small animals lack appendages and rely on cilia to glide over surfaces.
Unlike other worms these freshwater flatworms are unsegmented. They are acoelomates, meaning that they lack a coelom or a complete gut cavity. Their demonstration of bilateral symmetry has been linked directly to cephalization, the animals sensory organs are believed to have contracted towards a single particular side of the animal, forming an anterior end or a head region. This adjustment of nervous tissue over evolutionary generation results in a nervous system. Planarians possess distinct sensory organs that support the notion of cephalization, and make up their peripheral nervous system (Zhenghou, Henan ). They have ocelli, which are photoreceptors that are highly sensitive to light at the anterior end of their flat bodies and resemble eyes. Furthermore they have a supporting structure called a notochord that is attached to a longitudinal nerve cord.
Though they have a nervous system, these animals lack a fluid transport system. They carry out functions through osmosis and absorption, and rely upon diﬀusion for gas exchange. Their digestive system has one anterior and two posterior branches; it transports food throughout the entire body. Food enters the animal through the muscular pharynx, which is positioned in the center of the body and runs all the way to the single opening. They have an incomplete digestive system lacking an anus (Alvarado, Reddien). The mouth is used for both ingestion and egestion. Freshwater planarians can...