expt_block  date        mussel_density  prey_eaten  carap_width  sex  parasite  
9           2012-07-25  2               0           13.7         M    No        
9           2012-07-25  4               2           11.7         F    No        
9           2012-07-25  6               5           14.1         F    No        
9           2012-07-25  8               2           12.7         F    No        
9           2012-07-25  10              4           11.2         M    No        
9           2012-07-25  16              3           10.2         F    No        
9           2012-07-25  24              7           13.1         M    No        
9           2012-07-25  32              6           12           M    No        
9           2012-07-25  2               0           10.2         F    Yes       
9           2012-07-25  4               0           9.4          M    Yes       
9           2012-07-25  6               1           9.9          F    Yes       
9           2012-07-25  8               0           10           F    Yes       
9           2012-07-25  10              1           9.5          F    Yes       
9           2012-07-25  16              1           9.5          M    Yes       
9           2012-07-25  24              3           14.1         F    Yes       
9           2012-07-25  32              0           13.6         F    Yes