Horseshoe crabs Limulus polyphemus crawl beneath an oyster rack-and-bag farm during high tide at the lower Delaware Bay tide flats. Video taken with Didson sonar during incoming tide on May 21, 2019, during the spawning season. Some crabs in amplexus, and most being rocked gently by waves. The bottom is rippled with sand waves and the crabs become shaded as they move under the oyster bag.
A male crab moving beneath racks at low tide in shallow water.