Blending in with the free-floating masses of orange-brown Sargassum seaweed, Sargassum swimming crabs depend heavily on their ability to swim. As with other swimming crabs, they come equipped with tiny swim paddles on their hind legs. They are, however, also capable of crawling on land. Sargassum swimming crabs aren’t alone in this fragile, complicated mini-ecosystem. There are as many as 70 species living in these floating masses. Their neighbors include shrimp, flatworms, hydroids, tiny fish, seahorses and the Sargassum anemone. Also joining the crabs in the seaweed, are numerous other creatures, including tiny fish and larval crabs. Sargassum swimming crabs both aggressively hunt and wait for prey to wander close enough to deliver an unsuspecting lethal jab. The crabs also feed on less complex invertebrates, such as hydroids and bryozoans, which also inhabit the seaweed. These layers of interdependence in their share Sargassum seaweed home, enable these crabs and other species to thrive and coexist.