Planaria is a small invertebrate animal that belongs to Phylum Platyhelminthes (the flatworms). This amazing animal of Family Planariidae (the planarians) has the amazing ability to regenerate its lost body parts. Humans don’t have this ability that is why scientists are studying the organism hoping that they could find the explanation why the organism is able to regenerate and why advance organisms like humans could not. They are looking for the genes that confer regeneration ability to planaria and how could these genes be possibly integrated to the human gene.
Planaria measures 3 to 12 mm in length. It has a head and an elongated tail. The head has two eye-spots that detect light and a muscular mouth that sucks food. The ventral side of the tail has cilia used by planaria to glide in the mucus that it has secreted.
The planaria avoids light because it is a potential source of heat that can dehydrate the organism. It uses its two eyespots to detect light in the environment.
Planaria are independent organism, meaning they don’t parasitize other organisms in order to live. It is found both in salt water and freshwater environments.
Planaria feeds small animals that are dead or alive.
Planaria produces offspring sexually or asexually. Sexually, planarians produce gametes for reproduction. Asexually, planarians can cut a body part (e.g. tail) that can regenerate and form a new flatworm with complete body parts.
Planaria Regeneration Experiment
To observe how planaria regenerate, you will be needing planaria which you can get in freshwater ponds. You can also buy planaria from a local store selling biological supplies.
Dugesia sp. is the most common planaria used in regeneration experiment. Below is a picture of Dugesia sp.
Once you have the flatworms, put them in petri dishes with little water. Put only one planaria for a single petri dish. Don’t forget putting water into the petri dishes to prevent the flatworms from being dehydrated. Don’t also put the petri dishes with the planarians in a place with direct sunlight.
Now, you are ready to cut the planarians. Use a scalpel to cut the body of the planaria. You can cut the flatworm crosswise (separating the head from the tail) or lengthwise. For more ways on how to cut the planaria, look at the picture below.
Once you are finished cutting the planaria, leave them for a while. You can check them daily, and observe the changes. From one planaria in a petri dish, how many planarians can you see in the petri dish after few days?