Five specimens of Costasiella formicaria were found on sand in about 18m of water by Jay Lord on a Kwajalein Atoll lagoon slope. In Bali, this species appeared to be eating cyanobacteria growing on the sand. It caused me to wonder if perhaps all species of Costasiella, even those found almost exclusively on Avrainvillea algae, were just eating the cyanobacteria growing on the algae; their grazing does not seem to diminish the size of the algae blade they are on.
Created 15 February 2019
Updated 18 May 2021