Deep on the ocean floor, microbes are hard at work building huge structures literally from thin air – actually methane gas to be exact.
As a by-product of their metabolism, certain methane-consuming species of archaea (a single-celled domain of life) create, and then live inside, carbonate rock structures in the form of pavements, slabs and mounds. They are not the only ones who take advantage of these newly built structures - numerous animals also gravitate towards them. In fact, some scientists have suggested that methane seeps and the resulting carbonate outcrops should be considered ‘essential fish habitats’ and protected from any human-related destruction (ex. from mining or oil recovery activities). On our dive today, at a site known as ‘Fossil Hill’, we saw 100’s of rockfish and flatfish (both important fisheries for humans) hanging around the area. Some even watched us sample the other animal we were very interested in collecting – the 20,000 year old fossilized serpulid tubeworms that give this site it’s name. These worms died en masse a long time ago, but we wonder why they were here in such large numbers. We suspect that they too were reliant on methane gas via a partnership with bacteria in their tentacles – a capability demonstrated in our recent paper on a living relative (Laminatubus) from Costa Rica. You can find out more about that symbiotic relationship in our paper in press with Science Advances (doi.org/10.1101/2019.12.23.