# Temperature relation to Archimedes principle

I have a probably very simple problem which I cant solve. I am weighing animals in seawater by placing them on a small PVC arm that is fixed on a balance and reaches into a beaker of seawater. On the arm, I place an organism and measure the specific weight of the animal. Now, the weight of the animal changes a lot between days which cannot be explained by physiological processes. I believe this might be due to the water temperature which I also collect alongside. Can anybody tell me how to correct for water temperature if I dont know the volume of the organism?

Sample data:

• There are two things that would help regarding an answer. Use consistent precision when reporting data (e.g., 0.16 should be reported as 0.160). Also, describe the details of how the organism is weighed, hopefully including a picture. – David White May 31 at 21:18
• I have this idea that the odd drop of water trapped in or around the shell / organism could be sufficient given the size of the readings... – user207455 May 31 at 21:21
• For the first animal, $w_{1}=[0.213\ 0.217\ 0.214\ 0.201],$ the mean=$0.21125$, variance=$0.049583$, std-deviation=$0.0070415$ - or roughly $0.211\pm 0.007$. The most common error is parallax. Also, is the water content consistent? Maybe take a sample of the water and weight it when you weigh the animals so you can determine if the density of water is changing significantly. And measure a drop water. – Cinaed Simson May 31 at 21:48