Marine Life & Conservation
Study solves deep diving devil rays’ warm brain mystery
A new study shows that devil rays dive nearly 2km below the ocean surface, making some of the deepest and fastest dives ever observed in the sea.
Scientists tracked 15 of the large, winged fish, previously thought to be surface dwellers, for several months.
In between their icy dives, they appear to bask near the surface to warm up.
The findings from the study offer an explanation for a mysterious mass of blood vessels, thought to keep the ray’s brain warm.
The front part of the animal’s skull is stuffed with a sponge-like mesh of large and small arteries. This network, called a rete mirabile, was discovered in the devil rays 30 years ago.
“It was a mystery as to why they had this system, which is a way of keeping brain activity high, even in a cold environment,” said Dr Simon Thorrold, an ocean ecologist at the Woods Hole Oceanographic Institution and the new paper’s lead author.
The scientists who discovered the rete mirabile in devil rays were so baffled by its presence in a warm-water species that they even suggested it might be working in the opposite direction from usual, helping cool the brain while the rays basked in the sun.
Dr Thorrold’s results appear to have solved that mystery. “We looked at the data and of course, it made complete sense.”
He believes the rays are feeding at the bottom of their remarkable dives, using a well-heated, active brain to forage for small fish that abound in deeper layers of the ocean.
To reveal the ray’s secret submarine lifestyle, Dr Thorrold and his colleagues tagged 15 Chilean devil rays (Mobula tarapacana) using special tags tethered to darts.
“We actually jump in the water and tag them ourselves,” he said. “We take a polespear, we swim down and deploy the tag. The animal’s not restrained in any way.”
The researchers don’t suffer either. “It’s pretty good work, right? Free-diving in the Azores.”
This autonomous Portuguese archipelago happens to be one of the best places to find these particular devil rays, since they congregate there in the summer, around the top of underwater mountains.
But then, in the autumn, they disappear. “We had no idea where they were going,” said Dr Thorrold. “We had an idea that they were moving a long way, perhaps several thousand kilometres.”
That was where the tags came in. These programmable gadgets recorded depth, light, temperature and position data for up to five months, before detaching themselves and bobbing to the surface, where they beamed their data back to the researchers via satellite.
Perhaps unsurprisingly, the rays all headed south, with several being tracked almost as far as the equator.
This was the first time devil ray migration had been recorded and the distances were as much as 3,800km. But it was the other measurements that got the team excited.
“The first thing I looked at was the temperature data,” said Dr Thorrold, “and I saw temperatures of about 4C – and this is an animal that’s supposed to be living in the tropics! I suspected there was probably a mistake.”
The depth data confirmed, however, that the freezing temperatures were a result of incredibly deep dives, typically lasting 60-90 minutes and reaching 1,848m beneath the waves.
Very few fish, among them whale sharks, have been shown to dive this deep, and the all-time record (2,992m) is currently held by a mammal: the beaked whale.
During the day (but not at night), the devil rays tend to loiter within 2m of the water surface for periods before and after their deepest expeditions. This suggests they are using the sun’s warmth to prepare and recover.
One ray plunged below 1,400m on six consecutive days – behaviour that places these devil rays “right at the limit” of known diving behaviour, according to Dr Thorrold.
What is more, they were fast. The rays swam downward at up to 22km/h (13mph), which is much faster than sharks and whales typically descend.
That speed is another surprise. Because the rays are negatively buoyant, they could simply allow themselves to sink, gliding with little effort to their deep-sea feast.
“Our rays are swimming basically as hard as they can, straight down,” said Dr Thorrold. He believes this is another strategy for keeping warm.
Heat generated by their muscles could be stored and used by the specialised brain blood supply, to keep brain function high in the icy depths.
Dr Thorrold says the new findings highlight how little is known about these deeper ecosystems.
“We’re hoping that the rays are going to lead us to some really interesting biology, at depth, that we wouldn’t necessarily have been able to find ourselves – but we can use the rays to lead us to the biologically interesting layers and zones within those depths,” he said.
“These rays, in effect, connect the surface, epipelagic layers in the ocean, with the mysterious deep.”
Source: bbc.co.uk/news
The Ocean Cleanup, the global non-profit project, has removed a verified all-time total of ten million kilograms (22 million lbs.) of trash from oceans and rivers around the world – approximately the same weight as the Eiffel Tower.
To complete its mission of ridding the oceans of plastic, The Ocean Cleanup uses a dual strategy: cleaning up the Great Pacific Garbage Patch (GPGP) to remove the plastic already afloat in the oceans, while stopping the flow of plastic from the world’s most polluting rivers.
Through cleaning operations in the GPGP and in rivers in eight countries, the cumulative total of trash removed has now surpassed ten million kilograms. This milestone demonstrates the acceleration of The Ocean Cleanup’s impact, while underlining the astonishing scale of the plastic pollution problem and the need for continued support and action.
While encouraging for the mission, this milestone is only a staging point: millions more tons of plastic still pollute our oceans and The Ocean Cleanup intends to continue learning, improving and innovating to solve this global catastrophe.
This announcement comes as governments from around the world meet to continue negotiations to develop a new legally binding instrument to end plastic pollution at INC4 in Ottawa, Canada. Representatives of The Ocean Cleanup will be in attendance and the organization will be urging decision-makers to collaborate towards a comprehensive and ambitious global treaty which addresses plastic at all stages of its life cycle and in all marine environments worldwide, including in areas beyond national jurisdiction.
It is encouraging to see that the need for remediation is reflected in the various options for potential treaty provisions. It is essential that the final treaty contains clear targets for the remediation of legacy plastic pollution, and reduction of riverine plastic emissions.
Tackling plastic pollution requires innovative and impactful solutions. The treaty should therefore incentivize the innovation ecosystem by fostering innovations that make maximal use of data, technology and scientific knowledge – such as those designed and deployed by The Ocean Cleanup.
‘After many tough years of trial and error, it’s amazing to see our work is starting to pay off – and I am proud of the team who has brought us to this point.’ said Boyan Slat, Founder and CEO of The Ocean Cleanup. ‘While we still have a long way to go, our recent successes fill us with renewed confidence that the oceans can be cleaned.’
The Ocean Cleanup was founded in 2013 and captured its first plastic in 2019, with the first confirmed catch in the GPGP coming soon after the deployment of Interceptor 001 in Jakarta, Indonesia. After surpassing one million kilograms of trash removed in early 2022, the non-profit project has since progressed to the third iteration of its GPGP cleaning solution, known as System 03, and a network of Interceptors currently covering rivers in eight countries, with more deployments set for 2024.
About The Ocean Cleanup
The Ocean Cleanup is an international non-profit organization that develops and scales technologies to rid the world’s oceans of plastic. They aim to achieve this goal through a dual strategy: stemming the inflow via rivers and cleaning up the legacy plastic that has already accumulated in the ocean. For the latter, The Ocean Cleanup develops large-scale systems to efficiently concentrate the plastic for periodic removal. This plastic is tracked and traced through DNV’s chain of custody model to certify claims of origin when recycling it into new products. To curb the tide via rivers, The Ocean Cleanup has developed Interceptor™ solutions to halt and extract riverine plastic before it reaches the ocean. Founded in 2013 by Boyan Slat, The Ocean Cleanup now employs a broadly multi-disciplined team of approximately 140. The foundation is headquartered in Rotterdam, the Netherlands.
For more information, visit: theoceancleanup.com and follow @theoceancleanup on social media.
Marine Life & Conservation
Steve Backshall to headline Shark Trust’s flagship event: For the Love of Sharks
Join a host of amazing, shark loving, speakers including Steve Backshall and the Shark Trust team for an evening celebrating shark conservation at the Royal Geographical Society in London this November.
Date: 29th November 2024
Time: 6-10pm
Location: Royal Geographical Society, London
Tickets: https://www.sharktrust.org/Event/flos24
The event will be a celebration of all things shark. Those lucky enough to get hold of tickets will hear from engaging guest speakers with a passion for sharks.
The line-up includes (*subject to change if unforeseen circumstances arise)
Steve Backshall: One of television’s busiest presenters, BAFTA award-winning wildlife expert Steve has been passionate about the wild world ever since he was young.
Steve’s impressive TV career has taken him all around the world, investigating a wide array of species and environments. Steve has filmed over 100 hours of children’s wildlife programmes with the BAFTA award winning Deadly 60 franchise and recently, with Sky Nature, for his new series ‘Whale with Steve Backshall’. He has been a patron for the Shark Trust for 10 years.
Simon Rogerson: is a photojournalist specialising in natural history, diving and the sea.
He is editor of SCUBA magazine, the official journal of the British Sub-Aqua Club. Simon started his career as a crime reporter but gravitated towards his ‘less depressing’ interest in underwater exploration, joining the staff of DIVE magazine in 1999. In 2005 he was named ‘Editor of the Year’ in the PPA’s Independent Publishing Awards. Simon also works as a freelance writer, contributing frequently to the Sunday Times and Telegraph, in addition to BBC Wildlife, Esquire, and a host of international diving magazines. He is the author of a book, Dive Red Sea, published by Ultimate Sports. Now based in Berkshire, Simon has been a Patron of the Shark Trust for 20 years.
More speakers to be announced soon. Head to the Shark Trust website to learn more.
The evening will also allow guests the final chance to see the Oceanic 31, shark art exhibition. Some of the artwork will be auctioned/raffled at the event, while the rest will be auctioned online to raise money for the Shark Trust Oceanic Programme.
For the Love of Sharks is an evening with something for everyone who is interested and fascinated by sharks. Join the Shark Trust, their Patrons, Trustees and Staff, along with a host of supporters for this celebration of shark conservation.
For more information or to buy a ticket: https://www.sharktrust.org/Event/flos24
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