Virtually all zooxanthellate cnidarians appear to expel some of their symbiotic dinoflagellates from their
coelenteron on a daily basis (e.g., Reimer, 1971; Hoegh-Guldberg et al., 1987), whereas mass expulsion of zooxanthellae has been attributed to severe osmotic or thermal stress (Goreau, 1964; Jokiel and Coles, 1977, 1990; Jaap, 1979; Glynn, 1983).
Amoebocytes were extracted from the mesenteric filaments, located at the base of the
coelenteron, by making an incision into the center of the pedal disc and excising the filaments into a sterile 15-ml plastic centrifuge tube (Smith and Hutton, 1995).