Food Supply, Feeding Habits, and Egg Production in Pacific Mole Crabs (Hippa pacifica Dana)

Abstract

Well-studied hippid sand crabs (genus Emerita) on wave-washed beaches in the temperate zone obtain their food by filtering microorganisms from the water. Related mole crabs (genus Hippa) in the tropics and subtropics have raptorial feeding appendages, which permit these animals to grasp and feed upon fresh meat items. They apparently depend upon those organisms that move onto beaches as a result of wind-driven surface waters. In Hawaii, Portuguese men-of-war (Physalia) is the most obvious natural food supply, but tests with other types of bait indicated that shark or squid are equally effective in capturing animals. At Enewetak Atoll, where Pkysalia occurs only rarely, mole crabs thrive on mysids and perhaps other similar-sized zooplankton. There also existed a strong correlation between food availability and egg production, both in Hawaii and at Enewetak Atoll. In fact, an observed" seasonality" in egg production seemed to be a direct result of food availability rather than of changes in temperature or photoperiod.