expt_block  date        mussel_density  prey_eaten  carap_width  sex  parasite  
5           2012-07-19  2               0           12.4         M    No        
5           2012-07-19  4               1           12.9         M    No        
5           2012-07-19  6               0           11           F    No        
5           2012-07-19  8               1           12.5         M    No        
5           2012-07-19  10              0           12.1         M    No        
5           2012-07-19  16              4           12           F    No        
5           2012-07-19  24              6           12.3         F    No        
5           2012-07-19  32              11          12.2         M    No        
5           2012-07-19  2               1           10.7         F    Yes       
5           2012-07-19  4               2           11.8         M    Yes       
5           2012-07-19  6               0           13           F    Yes       
5           2012-07-19  8               2           11.4         M    Yes       
5           2012-07-19  10              0           13.5         M    Yes       
5           2012-07-19  16              0           10.5         M    Yes       
5           2012-07-19  24              0           11           F    Yes       
5           2012-07-19  32              1           10.5         F    Yes