Where it roofs the mantle cavity, the thin mantle contains many haemolymph vessels which are occasionally visible (1) through translucent juvenile shells or on dissected mantle (2). Oxygen from inhaled air diffuses into the haemolymph and carbon dioxide escapes from it to leave with the exhaled air.The vessels are more widely spread on the specimen in water on the right as the mantle has absorbed water and expanded to protrude from the shell rim. A bubble of air remains in the cavity of the immersed specimen. Long submersion with water in the mantle cavity is well tolerated if the water’s oxygen content is high (Seelmann, 1968, in Gittenberger, 2004).
22 Myosotella myosotis. Left in air, right in water. Salting on Severn Estuary, Gloucestershire, England. August 2011.
