Growth and Behavior of Trichoplax adhaerens: First Record of the Phylum Placozoa in Hawaii

Abstract

I report here the first record of Trichoplax adhaerens F. E. Schulze (phylum Placozoa) in Hawaii. Individuals were found on glass slides placed in the seawater system of the Pacific Biomedical Research Center on Kewalo Basin, Oahu, during November and December 1986. Records of growth rates of Hawaiian placozoans, in the laboratory at about 23°C, showed a doubling time ranging from 1 to 3 days, both in numbers (by fission) and in biomass (estimated by area). In a test for substrate preference, the animals favored conditioned glass slides (left in seawater for several weeks) over clean glass slides. A strong reaction to ultraviolet was observed.