BS in Biological Sciences
Biological Sciences Department
Emerita analoga, Pacific coast sand crabs, are an important biological component of the swash zone ecosystem. They have evolved the ability to burrow into sand, and burrowing speed is commonly used as an indicator of performance relevant for fitness in this species. Sand grain size varies among beaches, and crabs may be better adapted to to burrow in some sand types. We performed a completely crossed 3-factor experiment to determine how the sand grain size associated with beach-of-origin and rearing conditions influence burrowing in coarse and fine sand. Crabs from a fine sand beach and a coarse sand beach were housed in both fine and coarse sand. The burrowing speed of each crab was tested in fine and coarse sand five times over ten weeks. Crabs were housed individually during the ten weeks, in either coarse or fine sand. We found a significant difference in burrowing times throughout sessions. Crabs from both beaches, housed in both sand types, burrowed faster in coarse sand than in fine sand. However, neither beach-of-origin nor rearing sand type influenced burrowing speed. There was also no difference in mortality among treatments. These results indicate that, although the abiotic factor, sand grain size, influences burrowing speed, this effect is not altered with long term exposure to different sand types.