The California Beach Hopper is found along the eastern Pacific Coast from British Columbia south to Mexico. It is the largest amphipod on British Columbia beaches.
It inhabits temporary daytime burrows in the sand just above high-tide mark, and emerges at night to feed on seaweeds cast up by the tide. During the day these amphipods are found in their hundreds sheltering under, and feeding on, moist algae in the strand-line. As the tides cycle through springs and neaps, the amphipods dutifully follow, orientating to sand-moisture and beach-slope cues. Slopes differing by just a couple of degrees are discernible to the wandering amphipod. On a larger scale, if this species behaves similarly to its Californian counterpart M. corniculata
, it can also orientate to local beach landmarks and to celestial cues, notably the moon. Chief predators are birds and carnivorous rove beetles such as Thinopinus pictus
. For information on the celestial navigation, tidal rhythms, and burrowing of the California Beach Hopper go to A SNAIL'S ODYSSEY.
Note author: Tom Carefoot, Department of Zoology, University of British Columbia.