Researchers found that a species of ant called Sericomyrmex amabilis directly converts atmospheric carbon dioxide into a mineral armor that coats their exoskeletons. This species is the first known animal to produce partially ordered dolomite.
Sericomyrmex amabilis. AntWeb. Version 8.114. California Academy of Science, online at https://www.antweb.org.
The mineral layer is 7 to 20 micrometers thick and covers almost the entire body of mature worker ants, except their antennae, mandibles, the centers of the eye facets and leg tips. The mineral is partially ordered dolomite, a form never before reported in any animal.
The dolomite problemcan
Dolomite is one of the most abundant minerals in ancient rock formations, but it is very difficult to produce in the laboratory. At room temperature, the magnesium ions required to form dolomite are surrounded by a tightly bound shell of water molecules that must be displaced before the mineral can crystallize. Synthesizing it artificially typically requires temperatures exceeding 100 °C. In geology, this is known as the ‘dolomite problem’. Identifying the proteins involved in the process in S. amabilis could open a pathway toward biomimetic synthesis of high-magnesium carbonate materials, potentially enabling the engineering of harder, more stable materials or informing low-energy industrial processes for carbon mineralization.
To prove that the ants were converting CO2, the researchers exposed them to isotopically labeled 13CO2. This allowed them to trace the carbon directly to the mineral layer on the ants’ exoskeletons, showing that the carbon in the exoskeletons came from the air, not from the ants’ food.
The mineral armor is physically harder than that of related ant species, providing better protection against predators and fungal pathogens. Additionally, the process removes toxic CO2 from the ants’ underground nests, which can often reach dangerously high levels due to the metabolic activity of dense populations and fungus.
A similar process is also seen in geological carbon mineralization, where carbon is sequestered in rocks over millions of years. Understanding how these ants rapidly form dolomite at ambient temperatures, something that normally requires extreme heat in the lab, could offer clues for engineering better carbon capture and storage technologies.
