A stealthy autonomous underwater robot that can track elusive underwater creatures without disturbing them could help us better understand the largest daily migration of life on Earth. Mesobot, a 250-kilogram robot that operates either unconnected to a power source or tethered with a lightweight fibre-optic cable, is able to move around below the surface unobtrusively. The ocean's twilight zone – known more formally as the mesopelagic zone – lies between about 200 metres and 1 kilometre in depth. It is the site of the diel vertical migration (DVM), a daily phenomenon during which deep-dwelling animals come closer to the surface to feed on the more plentiful food supplies found there, while dodging predators. The DVM is seen by biologists as a very important way in which nutrients – and carbon dioxide captured via photosynthesis – can be rapidly transported to depth, where carbon can be stored for the long term.

A strange sea creature that lives 1,000 feet below the surface encased in a giant bubble of mucus may be key to removing carbon dioxide from the atmosphere. These bubble-houses are discarded and replaced regularly as the animal grows in size and its filters become clogged with particles. Once discarded, they sink to the seafloor and encapsulate the carbon for good, preventing it from re-entering the atmosphere. Larvaceans also capture and dispose of microplastics in this way, which can come from clothing and cosmetics and often ingested by other marine species. Researchers used a system of lasers mounted on a 12,000 pound robot to map the giant larvacean's delicate body in a series of 3D images.