Sea butterflies repair shell damage from ocean acidification

A new study of tiny marine snails called sea butterflies shows the great lengths these animals go to repair damage caused by ocean acidification. The paper, led by researchers at British Antarctic Survey, is published this month in the journal Nature Communications.

The ocean absorbs around one quarter of the carbon dioxide (CO2) emitted into the atmosphere and this CO2 reacts with seawater, causing the pH to fall, a phenomenon called ocean acidification. It has been feared this acidification is detrimental to certain organisms as corrosive waters could dissolve their shells or skeletons. Sea butterflies, also known as pteropods (Limacina helicina), are mm-scale animals that are prevalent in the polar regions. They have evolved 'wings' instead of a foot, enabling them to swim through the ocean. Their delicate shells are made from aragonite, the least stable form of calcium carbonate, and are so thin they are completely translucent.

Despite their anticipated vulnerability to ocean acidification, the study found that sea butterflies in the Greenland Sea show certain adaptations to their environment. Not only do they protect the outsides of their shells from corrosive waters with an impermeable membrane, much like cling-film, but they can also repair damage to their shells.

For the first time, BAS scientists have observed sea butterflies repairing shell damage by making new calcium carbonate to patch themselves up from the inside.

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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 Arctic 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.

 

The mystery of how a sea snail moves through water has been resolved: they move their wings just like flies do, generating lift to keep afloat.

 

 

The pteropods are a fascinating group of snails that spend their entire lives swimming or drifting in the ocean and never touching the bottom. Pteropoda means wing-foot referring to their muscular foot that has evolved into a pair of wings allowing them to take advantage of the Earth’s largest habitat, the open ocean.

There are two distinct types of pteropods – those with shells and those without. The shelled pteropods produce a net of sticky mucous to passively collect and eat marine snow. The pteropods without shells are all carnivores and as far as we know, feed solely upon the shelled pteropods.

The pteropods are a widespread and diverse group, and play an important role in the oceanic food web. However, the increasing acidity of the ocean leaves the fragile pteropod shells vulnerable to dissolving, challenging the health and growth of these species. These impacts may reach beyond pteropods to the variety of animals, including fishes, sharks, squids, and marine mammals that eat them.

 

Wow, they look so delicate, so fragile.
Must be amazing to dive and see all the life beneath...... so tranquil... you must almost forget all the madness up above..

Thank you Dragon