expt_block  date        mussel_density  prey_eaten  carap_width  sex  parasite  
1           2012-07-17  2               2           14.6         M    No        
1           2012-07-17  4               0           12.7         F    No        
1           2012-07-17  6               2           11.9         M    No        
1           2012-07-17  8               1           13.5         M    No        
1           2012-07-17  10              7           13.3         M    No        
1           2012-07-17  16              2           11           F    No        
1           2012-07-17  24              1           11.6         F    No        
1           2012-07-17  32              0           12.1         M    No        
1           2012-07-17  2               0           13.1         M    Yes       
1           2012-07-17  4               3           12.1         M    Yes       
1           2012-07-17  6               0           10.9         F    Yes       
1           2012-07-17  8               2           11.4         F    Yes       
1           2012-07-17  10              0           11.7         M    Yes       
1           2012-07-17  16              0           11.7         F    Yes       
1           2012-07-17  24              1           10.8         F    Yes       
1           2012-07-17  32              1           13.5         M    Yes