Squid, it seems, may be among the most vulnerable, with consequences that could trickle through the marine ecosystem. A new study published May 31 in the journal PLOS ONE finds that squid raised in more highly acidified ocean water hatch more slowly and are smaller when they hatch than squid raised in ocean water at today's pH levels. The acid-exposed squid also have abnormal statoliths, which are internal, calcified structures that function like the mammalian inner ear to help squid keep their balance and orient themselves.