Science Buddies: "Ask an Expert"

I am investigating this question for my science fair project. I have cur my planarian and put them into separate dishes. I have also put some uncut planarian in separate Petrie dishes. Unfortunately the planarian are mostly curled up in the dishes. They are definitely still alive, but they are balled up so I can’t measure them. Any ideas on how I can get them to stretch out? (They were mostly stretched out when I started on this.)

Any help will be appreciated. Thanks.



[Administrator note: project: https://www.sciencebuddies.org/science- ... generation ]

Hi,

According to this Biology website, one way to measure is listed under step #5, "Measure your planarian. This operation is best performed by removing some of the water from the dish and waiting for the worm to stretch out. Measure the length of the worm in millimeters. (Always replace the water, you can use the dish lid to transfer water to and from the planarian environment.)"

https://www.biologycorner.com/worksheet ... acher.html

Hello,

You may want to try submerging your Planaria in cold fresh water at a temperature of about 21 to 23 C or about 70 to 73 F, which is typically the temperature that water should be kept at when caring for Planaria. Slightly colder water should keep the Planaria still long enough to stretch them out carefully for measurements. Be cautious to use the correct tools when doing this part of your project! A detailed procedure and materials list can be found here: https://www.sciencebuddies.org/science- ... #procedure

Another tip that may help you to stretch the Planaria out well enough to be measured and in an attempt not to harm the organism would be to use a pipette to transfer the Planaria to other locations, for example when changing the water of the habitat or moving the Planaria from wet/watery to drier locations.

Alternatively, removing Planaria from the water like my fellow mentor suggested may be worth a try as well since Planaria are expected to stick to surfaces such as a petri dish lid or other plastic containers/flat and cleanable surfaces where the water they live in is removed.

Hope this helps!
-cnoonan180