1. They can swim freely for short distances to escape predators or relocate themselves to a better spot. 2. They have lots of super tiny eyes… anywhere from tens to hundreds of 1mm eyes that line the edge of their shells. 3. They’ve been around for a long time. From Wikipedia:
The fossil history of scallops is rich in species and specimens. The earliest known records of true scallops (those with a ctenolium) can be found from the Triassic period, over 200 million years ago… Fossil records also indicate that the abundance of species within the Pectinidae has varied greatly over time; Pectinidae was the most diverse bivalve family in the Mesozoic era, but the group almost disappeared completely by the end of the Cretaceous period. The survivors speciated rapidly during the Tertiary period. Nearly 7,000 species and subspecies names have been introduced for both fossil and recent Pectinidae.
Here’s a closer look at their eyes. ScienceMag summarizes research from 2017 that “scallop eyes act just like tiny telescopes.”
Related reading in The New York Times: The Scallop Sees With Space-Age Eyes — Hundreds of Them.Next: The Stomphia coccinea sea anemone can also swim, a pacific razor clam burrows rapidly into the sand, and how is a nautilus different from a squid? Plus: More Hakai videos.