Around one-quarter of the carbon dioxide we release into the atmosphere dissolves into the ocean. Dissolved carbon dioxide makes seawater more acidic – a process called ocean acidification – and its effects include the shells of sea butterflies, also known as pteropods, that have begun
dissolving in the Arctic and Antarctic.
Pteropod, also called sea butterfly, small marine gastropods of the subclass Opisthobranchia (phylum Mollusca) characterized by a foot modified to form a pair of winglike flaps (parapodia) that are used for swimming.
They live at or near the sea surface; most are less than 1 cm (0.4 inch) long.
Those that lack a shell and have complicated mechanisms for capturing and eating other small animals constitute the order Gymnosomata; those having a shell and feeding by means of cilia and mucus constitute the order Thecosomata.
SEA BUTTERFLY/PTEROPOD( LIMACINA HELICINA)
RANGE: Arctic and Southern oceans.
The pteropod Limacina helicina is a tiny shelled marine snail that swims using a pair of converted feet as wings. It has earned the name “sea butterfly” because of its elegant swimming style, and “potato chip of the sea” because of its importance as a food source for so many marine species from zooplankton to seabirds to fish.
Limacina helicina starts life as a male and becomes female when it reaches a larger size. It captures its prey by casting a web of mucus that traps tiny plankton.
Pteropods are among the marine creatures most vulnerable to ocean acidification. Ocean acidification lowers the availability of the mineral aragonite that pteropods use to form their shell, hindering this snail from building its protective armor. Scientists have found that Limacina helicina exposed to acidic ocean conditions are significantly less able to build their shells. The decline of these key organisms would result in dramatic impacts for the entire marine food web.