Cirsotrema varicosum is the largest of the Epitoniidae known from Kwajalein. We have seen it exclusively associated with the anemone Heteractis crispa. The shells were usually found during the day hidden under the margins of the anemone, often buried in sand if there was any there. Heteractis crispa was at one time one of the most common anemones that hosted anemonefish at Kwajalein. However, it is extremely sensitive to coral bleaching caused by even slightly warming water from climate change. In all our experience dating back to the 1960s, there were no coral bleaching episodes at Kwajalein until 2009, when the water reached 30°C for the first time. Corals and anemones bleached in 2009, and again in 2013, 2014, 2016, 2017 and 2018, each time in water that peaked at 30°C or more. Heteractis crispa became rare after the first bleaching, and the last one we saw was a bleached specimen on 15 September 2014, in the early stages of the third bleaching event at Kwajalein. The anemone may now be extinct at Kwajalein, and if Cirsotrema varicosum feeds only on those, they will be gone as well.
With eggs (the sandy balls in front of the shell) under the tentacles of Heteractis crispa.
Created 17 April 2017
Updated 20 March 2020