16 Butterflies of the ocean

Delicate shell, sensible core: Pteropods are among the most vulnerable plankton species. With its foot developed into two wings, the “sea butterfly” flutters through the ocean.

Limacina retroversa grows to up to seven millimetres. Its left-coiled, high-spired shell is made of aragonite, a form of calcium carbonate that is easily affected by ocean acidification. In acidified water, the snails grow shells that are thinner than those produced at present-day conditions. At extremely low pH levels, the shells even start to dissolve.

Photo: Solvin Zankl