expt_block  date        mussel_density  prey_eaten  carap_width  sex  parasite  
8           2012-07-25  2               2           13.7         M    No        
8           2012-07-25  4               0           11.9         M    No        
8           2012-07-25  6               4           12.2         F    No        
8           2012-07-25  8               2           13.7         M    No        
8           2012-07-25  10              1           13.5         M    No        
8           2012-07-25  16              12          13.7         F    No        
8           2012-07-25  24              13          14           M    No        
8           2012-07-25  32              10          13.3         M    No        
8           2012-07-25  2               0           10.7         F    Yes       
8           2012-07-25  4               0           12.8         F    Yes       
8           2012-07-25  6               1           11           F    Yes       
8           2012-07-25  8               0           10.6         M    Yes       
8           2012-07-25  10              5           10.4         F    Yes       
8           2012-07-25  16              4           11.1         M    Yes       
8           2012-07-25  24              0           10.1         F    Yes       
8           2012-07-25  32              3           8.9          F    Yes