A simple method could be to make a movie

with a web camera. Compress it with zip.

The more action is in the scenery, the larger

the file.

Regards,

Joachim

Robson et al used a Hall (magnetic field) sensor connected to a logger and were able to see high resolution changes in gape.

http://link.springer.com/article/10.1007/s00227-006-0566-z

There are different instruments to monitor the mussel valves movement , some traditional and others more sophisticated. Recently appeared this article that I found interesting:

"Effects of the toxic dinoflagellate Heterocapsa circularisquama on the valve movement behaviour of the Manila clam Ruditapes philippinarum" ,

Aquaculture, Volume 291, Issues 1–2, 3 June 2009, Pages 41-47 ;

Leila Basti, Kyohito Nagai, Yohei Shimasaki, Yuji Oshima, Tsuneo Honjo, Susumu Segawa

Regards

Lya

Hi, Borcherding et al. developed a valve opening monitor for Dreissena polymorpha. Maybe u can use something like that:

http://link.springer.com/article/10.1007%2Fs10750-005-1203-4#

For one of my experients this appraoch was a bit of an over kill though and I estimated the valve opening behaviour simply by observation. That worked relatively well but was quite laborious. And I ended up with a binary data set (open - closed).

Dear Dr. Ajit Kumar Mohanty

I did point related to your question in my M.Sc. work

Ali, R. F. (2006). Studies on some snails associated with different crops. M.Sc. Thesis, Fac. Agric. Cairo Univ., 153 p.

I attach my answer by a pdf ..it was part of my thesis .. hope will be helpful for you

yours

Reham Fathi