ABSTRACT
The goal of this review is to highlight what little is known, and point to the bulk of what is yet to be learned, about the natural history of placozoans in the fi eld-in order to stimulate a broader search for placozoans and a fuller exploration of their distribution, diversity, and all other aspects of their enigmatic lives. The documented geographic distribution of placozoans lies mostly in the nearshore, warm, marine waters of the tropics and subtropics. Although placozoans have long been viewed as benthic organisms, they can be more readily collected from the water column, well above the sea bottom. The full life-history of placozoans is unknown, including the nature of this abundant pelagic phase and all details of sexual reproduction and development. We note observations on the biota associated with placozoans in fi eld collections, in particular the other regular members of the microcommunity in which placozoans occur on our collecting plates and on some factors infl uencing this assemblage. Among the animals found are some potential predators against which placozoans appear to be defended. Yet to be uncovered is the full breadth of
1Long Marine Laboratory, Institute of Marine Sciences, University of California, Santa Cruz, CA 95060, USA. E-mail: vpearse@ucsc.edu, vpearse@gmail.com 2Department of Earth-and Environmental Sciences & GeoBioCenterLMU, LudwigMaximilians-Universität München Richard-Wagner-Str. 10, 80333 München, Germany.
