M. myosotis has a mantle cavity that functions as a lung for breathing atmospheric air, suitable for its habitat in the supralittoral zone which is only covered by water for about an hour on each of 2 to 6 days each month. When first submerged, a bubble of air may be retained in the mantle cavity (see image 19Mm 19 Myosotella myosotis. Adult. Height 7.5 mm. Salting on Severn Estuary, Gloucestershire, England. August 2011. Left: in water. Right: same specimen in air. ), but Gittenberger (2004) states, “Long submersion is well tolerated if the oxygen content remains high. The animals then take water into their breathing cavity” [translated]. The submerged specimen above has a small bubble of air escaping from the partially open pneumostome (1) which indicates that some water has entered the mantle cavity.
26 Myosotella myosotis. Shell height 6.2 mm. Salting on Dee Estuary, Cheshire, England. May 2018. Photographed in water.
