Ventilation Behavior of the Mantis Shrimp, HEMISQUILLA ENSIGERA CALIFORNIENSIS IN HYPOXIC BURROWS

The burrow-dwelling mantis shrimp, Hemisquilla ensigera californiensis, is an environmentally challenged marine species due to the fact it inhabits burrows located beneath the surface of the sediment where oxygen pressure is low and easily depleted. This experiment revealed that burrow oxygen pressure (pO2) is frequently hypoxic and can become anoxic. Average pO2 within the burrow is between 40-50 mm Hg and may drop below 10 mm Hg even if the burrow isn\u27t capped. When capped, p02 rapidly drops to 0 mm Hg within two hours. Low pO2 does not result in decreased animal activity, nor in movement of the animal toward the burrow entrance. Hemisquilla ensigera is capable of ventilating the burrow, but does not need to come to the entrance to do so. Ventilation is accomplished by prolonged pleopod beating while assuming a specific posture, rather than by whole-body movement, and may occur even while the animal is deep within the burrow. In this respect, H. ensigera is quite different from other marine crustaceans crustaceans which experience similar challenges of low pO2