However, physical marks such as drills and bite marks provide a conclusive indication that a particular midden is the remains of a foraging octopus. We described middens of Octopus dofleini from Prince William Sound, Alaska that were found at the mouth of a den containing an octopus or that contained at least one remain drilled by an octopus. Octopus dens were found by looking for a pile of excavated substrate at the base of a boulder, often littered with remains of crabs and molluscs. All litter bits were collected for later measurement and identification. All specimens collected were inspected for octopus drills or other signs of handling by octopus.
Octopuses use dens for shelter, and discard remains outside the den in midden piles.
Contents of middens yield important data for describing octopus diets, yet the field signs for distinguishing octopus middens from remains left by other processes can be subtle. A previously undescribed mark in prey remains, the bite mark , occurred on the leg of Telmessus cheiragonus . Bites averaged 1.2cm long by 0.5 cm wide, and occurred on the inside and outside of the leg extending the entire length of the segment. References Anderson, R. C. 1994. Octopus bites clam.