BBC Science Focus
Floating through the deep sea are multitudes of intricate, gelatinous animals that are extremely difficult to study. They’re transparent, and so delicate that they easily fall apart when caught in nets. But now a team from the Monterey Bay Aquarium Research Institute (MBARI) in California has developed a new way of looking at them.
Dr Kakani Katija, MBARI’s principal engineer, has designed the DeepPIV (Particle Imaging Velocimetry). Attached to a deep-diving robot, the device uses a sheet of lasers to build 3D scans of transparent, intricate animals in their natural environment. Katija’s first targets were 10cm-long, tadpole-like animals called giant larvaceans, which make complex mucous structures to filter seawater for tiny food particles. The animal’s fist-sized filter looks a bit like a pair of fluted angel wings. “From an engineering perspective, these are some of the most amazing built structures I’ve ever come across,” says Katija.
Her team at MBARI’s Bioinspiration Lab used DeepPIV to scan the inner shape of a larvacean filter, and also tracked particles as the animal beat its tail and drew in water. This information will help them figure out how the filters work and how the animals build them. Already, DeepPIV has revealed that larvaceans filter 80 litres of water per hour and absorb masses of carbon-rich food. When they get clogged, the larvaceans jettison their filters, which then sink, therefore helping the oceans to take carbon into the deep. In fact, larvaceans are so abundant throughout the oceans that they play an important role in the carbon cycle.
Other researchers are interested in using DeepPIV, including people who are rethinking ways of exploring the ocean. “These 3D visualisation techniques, coupled to DNA extraction, may be sufficient to describe and catalogue life,” Katija says. In the future, rather than collecting and preserving dead animal specimens — which is especially tricky for delicate, gelatinous life forms — museums could use 3D scans as digital archives to help describe previously unknown species and document life in the vast deep oceans.