The population stability of the less abundantly represented, persistent species will be contrasted with that of the more abundantly represented opportunistic species. For the purposes of this study, the population stability of each species refers to the constancy of its population size structure over time. It is clear that specimens of some species are frequently encountered and appear to be relatively common while others are known from very few specimens and appear to be extremely rare. The ecological requirements of coral-reef starfish, as well as the role of both rare and common species, are not understood and it is not known whether rarity is a survival strategy, an abundance limit imposed by predators or a failure in competitive ability of a species on its path to extinction. These problems have not been addressed for asteroids or any other taxonomic group within the highly diverse and complex coral reef ecosystem.
Little information is available on the longevity of coral-reef starfish.
Little is known of the other coral-reef starfish species, and the reproductive patterns, population stability and diversity of starfish assemblages on reefs that have not carried population outbreaks of Acanthaster planci are poorly understood. Heron Reef is such a reef. It is a Marine National Park and is situated near the southern end of the Great Barrier Reef. Large-scale traverse sampling is analogous to manta tows that have been used to monitor populations of Acanthaster. This scale of sampling is useful to establish a general pattern of starfish abundance, but is not capable of providing detailed data on either microhabitat partitioning or small-scale abundance.