Read the following passage, then answer the question.

The octopus is among the ocean's most remarkable problem-solvers. In laboratory tanks, octopuses have learned to open screw-top jars to reach food sealed inside, sometimes after watching another octopus do it only once. They can squeeze their boneless bodies through gaps barely larger than their beaks, and some have been observed carrying coconut shells across the seafloor to assemble portable shelters. Such behaviors have led researchers to regard the octopus as one of the most intelligent of all invertebrates.