Can anyone tell me what is the largest size of opening one can have in a tank that still prevent escapes. I know the limitation is the size of beak. But what is the average size of the beak on a typical octopus? Maybe it would be helpful to know the "typical" size of an octopus as well. My experience has been 8" to 10" with arms outstretched. Any thoughts? Is there any info out there on the size of the beak as compared to the body size of the animal? I haven't found any.