Summary

Species in the family Zoanthidae, such as this Protopalythoa species, are anemone-like animals that live permanently attached to rock or a piece of coral, usually in the intertidal zone of reef crests. They have tentacles arranged around an oral disc, which are used in prey capture and defence. Many species in the genus Protopalythoa have symbiotic zooxanthellae present in their tissue, which allows them to gain energy from photosynthesis. The species that is investigated in this study is colonial, with multiple polyps connected to each other via a stolon. The colony was collected from the southern reef crest of Heron Island at low tide.

Close-up of Protopalythoa species polyp in colony. Note lack of coenenchyme and the particulate matter that has been incorporated into the mesoglea.

The colony was examined to determine if natural fluorescence was present, and two individual polyps were separated for histological sectioning. The experiment conducted is outlined on the page 'Anatomy and Physiology'. The presence of chlorophyll in this species was also tested, which would provide further evidence for symbiotic zooxanthellae being present in this species, and is outlined on the 'Ecology' page.

Natural fluorescence in a single Protopalythoa species polyp. Green indicates tentacle tips and mouth, with red as the oral disc. The yellow section in the oral disc is where natural fluorescence is both green and red.

The anemone-like animals in the class Anthozoa, such as Protopalythoa species, are not well studied (Mather & Bennett 1994; Soares et al. 2011), which has lead to difficulties in species definitions (Ryland & Babcock 1991).

Debate is occurring as to whether the two genera Palythoa and Protopalythoa should actually be considered one genus, “Palythoa” (Reimer et al. 2006; Reimer et al. 2007). To eliminate confusion, the species outlined in this webpage is referred to as Protopalythoa, based on morphological observations outlined by Davey (1998) and Reimer et al. (2006). For further information regarding this debate, see the page 'Evolution and Systematics'.

As classification of this species is difficult, and there have been very few studies conducted regarding this genus, no definitive statements about this organism have been stated. As a result, the descriptions of the organism presented here should be seen as a very minimalistic and general overview of the morphological characteristics, ecology and behaviour observed over the few weeks of study available while on Heron Island Research Station and at the University of Queensland.