Just finished reading the book that accompanies David Attenborough's new series "First Life" and found reconstructions of the Cambrian predator arthropod Anomalocaris posed very much like a cuttlefish. Many see Anomalocaris as the predator of trilobites, using its grasping appendages (see the 9 cm Early Cambrian pair attached) to catch, hold and bite their trilobite prey (see attached Elrathia with bite wound from the Middle Cambrian of Utah). I was thinking about Anomalocaris yesterday after watching Ramses devastate crabs (and sadly an anemone fish considered an old friend in this household). Ramses takes up position, with two upper arms raised, then shoots out the tentacles without moving his body forwards and then, approximately at the same time as contact with crab (too fast to resolve on the video), shoots his whole body forward to envelope and pick up the prey with the arms (actually quite unlike a chameleon pulling the food back into its mouth). Fossils of Anomalocaris show no sign of anything like the cuttlefish's tentacles so I guess it would have had to launch its whole body in one go - perhaps easier to do from an ambush position, partly buried in the sediment? Who knows, just some idle thoughts. One marine biologist (Justin Marshall) suggested that Anomalocaris struck its prey with lightening-speed in the same way as mantis shrimp, "the fastest-known predators alive on the planet." (Here's a Cretaceous example, this one with a spine on the end of the appendage for impaling prey).