RESPIRATORY ADAPTATIONS OF THREE SPECIES OF UPOGEBIA (THALASSINIDEA, CRUSTACEA) WITH SPECIAL REFERENCE TO LOW TIDE PERIODS

¹ Zoology Department, Rhodes University, Grahamstown 6140, South Africa

At simulated low tide, Upogebia africana, U. affinis, and U. capensis moved to the air-water interfaces of their burrows and took up positions in which the cephalothorax was out of the water. The posterior end of the gill chamber dipped into the water and continuing scaphognathite beat pulled water up through the gill chamber. This behavior was induced in U. africana by exposure to low oxygen tension (pO₂) water. The median survival time of U. africana was 18 h in anoxic conditions and 72 h in air. U. afnicana has a low metabolic rate that may be an adaptation to hypoxic conditions. The blood pO₂ decreased rapidly when the shrimps were exposed to hypoxia and reached an equilibrium level after about 5 h. The pO₂ of blood of U. africana in air was approximately half that of shrimps in normoxic water.