Boy, I sure do love beach hoppers.
I recently backpacked the Ozette Triangle in Olympic National Park, the coastal section of which goes between Sand Point and Cape Alava. The route follows beaches and rocky intertidal habitat, offshore sea stacks, and sections of beach that are impassable depending on daily tidal cycles. I described it to my travel partner as "Mordor's beachfront resort property".
The wrack line contains kelp, seaweed, and other organic material deposited by the tide, and is home to the beach hopper.
Beach hoppers are small talitrid amphipods that feed on this kelp. Their munching helps break down organic matter and transfer nutrients from the marine environment into the beach ecosystem. Think shrimp-cricket.
Their chaotic leaping is a function of their tail rather than leg-powered locomotion. They curl into a C-shape and then straighten themselves rapidly, but cannot control the direction in which they fly. They respond to vibration and shadow, instinctively moving away from incoming tides so as not to be swept into the ocean.
Bonus close-up of the biggest boi, megalochestia corniculata:
It doesn't fling so much as flop; at an inch long it is heavy enough that it sort of rolls away rather than bounces. The average beach hopper is 1/5 its size.
