Tides and Trails

Welcome to the second Tides and Trails installment of Crabby Monday! Pacific shores are stalked by the Pacific Rock Crab, Cancer antennarius, pictured here, and by its close relative, the Red Rock Crab, Cancer productus. Both species are denizens of the intertidal and shallow subtidal zones. Like many crab species, rock crabs are opportunistic and eat dead material along with a wide range of live animals: mussels, barnacles, snails, other crabs. The robust pinchers of rock cr

This shiny vessel from the sea is a mermaid’s purse—a capsule for the eggs of the big skate (Raja binoculata). Sharks also make mermaid’s purses to protect their eggs. Rays, the cartilaginous cousins of skates and sharks, don't use purses but instead bear live young. The hooked ends of a mermaid’s purse latch to solid surfaces on the seafloor, but the capsules can tear loose from the ocean bottom and wash onto shore. Beach-cast purses often arrive empty, but sometimes they co