A robotic dodecahedron can capture fragile deep-sea animals to collect tissues samples and construct three-dimensional scans of the creatures, potentially speeding up the cataloguing of the up to 66 per cent of ocean species that are yet to be described by science.
Brennan Phillips at the University of Rhode Island and his colleagues developed the RAD2 sampler, designed to mount on any submersible, to collect fresh tissue samples from living animals in situ. They hope this will reveal more about the creatures than existing techniques, which typically put them under stress as they are hauled from the depths.
RAD2 is a dodecahedron with an internal volume large enough to hold a basketball. It is designed to fold and unfold on command to temporarily capture creatures for closer examination, taking a small tissue sample that is preserved directly on the submersible for later genetic analysis.
The ultimate aim is to take a small biopsy and then release the animal relatively unharmed, but RAD2’s current technique – called tissue cleaving – is “a bit cruder”, says Phillips.
RAD2 has already been tested on two excursions, collecting up to 14 tissue samples a day at depths of around 1200 metres. “We were able to get small pieces of tissue and sometimes we got the whole animal,” he says. “It kind of depended on how big it was. So, I can’t go as far as claiming that we were able to release the animal unharmed afterwards, but we are moving towards that.”
The robotic sampler also carries a 4K-resolution video camera to take high-quality footage of the animal in motion, while virtual models of it are built by different 3D scanning devices. In the future, each of the dodecahedron’s 12 faces could contain a sensor to take various measurements of the creature in one go, says Phillips.
Phillips calls other sampling methods “old school”, saying they essentially involve manually putting things in jars for later analysis, or using submersibles to do the same.
With the preservation happening at the point of collection with RAD2, Phillips says the quality of tissue samples will be higher and even allow researchers to detect which genes are being expressed, potentially shedding more light on an animal’s behaviour and physiology. “This is the high-grade stuff,” he says. “This is the best you’re ever gonna get of this animal, better than anybody has ever got before.”
Eva Stewart at the University of Southampton, UK, says that digital data on deep-sea creatures can be a useful tool for research, but that there is no substitute for capturing and storing whole samples.
“We have thousands and thousands of type specimens here [at the university],” says Stewart. Some of them were collected by the Swedish scientist Carl Linnaeus, she says, who died in 1778. “People go back to look at them, take bits of tissue or scan them. Once you’ve got a specimen, you’ve got it. Even as our science changes, you can keep going back to it.”
But Stewart agrees that underwater scanning could be useful for gelatinous and other delicate animals, which can be hard to collect intact, and for understanding how creatures behave in their natural environment, rather than after having been hauled onto the deck of a boat.
“We’ve been doing some work looking at genetic expression in sea cucumbers, because we want to see what they do when they’re stressed, if they’re impacted by climate change or something,” says Stewart. “But when you collect them and bring them to the surface, that’s stressful. So getting the tissue from them more naturally means you could then potentially look more clearly at what happens when they are put in different circumstances because you know what their natural baseline is.”