you're reading...


Daredevil: Chilean devil rays dive to extreme depths and escape without brain freeze

Thorrold, S., Afonso, P., Fontes, J., Braun, C., Santos, R., Skomal, G., Berumen, M., (2014). Extreme diving behaviour in devil rays links surface waters and the deep ocean. Nature Communications. 5(4274). DOI: 10.1038/ncomms5274

A group of Chilean devil rays.

Photo Credit: Nuno Sá: A group of Chilean devil rays.

The Chilean devil ray, Mobula tarapacana, was up until now thought to live near the surface in warm temperate and tropical sunlit waters, basking in the sun with mojito in fin.  This large ray not only wins badass points for being named after ‘el diablo’, but its species name also surpasses the word ‘banana’ in a literary sense.  Scientists have long been baffled by the presence of retia mirabiliai, essentially a heat exchange system that shunts heat generated from red muscle fibres in the rays’ pectoral fins to the brain and other organs. Why would M. tarapacana need to keep their brains warm if they resided in warm waters anyway?

By tagging fifteen M. tarapacana individuals from 2011-2012 in the central North Atlantic Ocean, Thorrold et al., gained a deeper understanding of these elusive creatures.  All tagging was completed at the Princess Alice seamount using popup satellite archival tags.

The results

From Thorrold et al., 2014. Dive profiles of M. tarapacana at 75 s intervals. (a) Depth and temperature profiles at from three day dives (6:00-18:00). (b) Depth and temperature profiles from three night dives (18:00–6:00).

From Thorrold et al., 2014. Dive profiles of M. tarapacana at 75 s intervals. (a) Depth and temperature profiles at from three day dives (6:00-18:00). (b) Depth and temperature profiles from three night dives (18:00–6:00).

Not many animals consistently dive past the mesopelagic into the bathypelagic zone (1,000-3,000 m depth) because of the cold temperatures (<5°C), high pressures and low levels of dissolved oxygen. However, results from this study show that for M. tarapacana, diving to daredevil depths is just another day in the life.  Two distinct patterns of dive profiles beyond 800 m emerged.  The most common dive profile was classified as a foraging dive and consisted of a fast descent with slower return to surface.  Foraging dives totaled 60-90 min. long and only  happened once in 24-hours.  In contrast travelling dives consisted of staying at depths of up to 1,000m for up to 11 hours.

Dive profiles also varied depending on time of day.  During daylight hours (6am-6pm), rays made deeper and longer dives, diving down faster and returning to the surface slower. They also spent more time at the surface an hour before and after the dive to warm up their bodies in preparation for or recovery from a deep, cold dive.  Under the cover of darkness (6pm-6am), dives were shallower, shorter, and descent time was on par with ascent time with no pattern of surface residency before or after.  See figure on left.

Ultimately, these rays do not only travel far horizontal distances, but they are also among the ocean’s deepest and fastest descending divers. M. tarapacana were found to dive beyond 1,800m, reaching descending speeds of up to 6m/s which surpasses the descent rates of beaked whales and sperm whales (other deep divers) at 1-2m/s, as well as Bluefin and yellowfin tuna at 4-5m/s.


Finally, the mystery of retia mirabilia in  M. tarapacana is solved–it exists to prevent brainfreeze when diving to extreme depths!  The results also show that basic ecological knowledge of myliobatoid rays is lacking.  In light of pressures from an increasing harvest rate for devil and manta gill rakers and high incidental catch in longline and tuna purse seines, additional research should be a priority.  Last but not least, these findings vertically link surface predators and prey at depths leading to implications for commercial fisheries such as bigeye tuna, swordfish, and blue sharks.




No comments yet.

Post a Comment


  • by oceanbites 5 days ago
    Leveling up - did you know that crabs have a larval phase? These are both porcelain crabs, but the one on the right is the earlier stage. It’s massive spine makes it both difficult to eat and quite conspicuous in
  • by oceanbites 2 weeks ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring Cierra Braga. Cierra works ultraviolet c (UVC) to discover how this light can be used to combat biofouling, or the growth of living things, on the hulls of ships. Here, you
  • by oceanbites 3 weeks ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Elena Gadoutsis  @haysailor  These photos feature her “favorite marine research so far: From surveying tropical coral reefs, photographing dolphins and whales, and growing my own algae to expose it to different
  • by oceanbites 1 month ago
    This week for  #WriterWednesday  on Oceanbites we are featuring Eliza Oldach. According to Ellie, “I study coastal communities, and try to understand the policies and decisions and interactions and adaptations that communities use to navigate an ever-changing world. Most of
  • by oceanbites 2 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Jiwoon Park with a little photographic help from Ryan Tabata at the University of Hawaii. When asked about her research, Jiwoon wrote “Just like we need vitamins and minerals to stay
  • by oceanbites 2 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring  @riley_henning  According to Riley, ”I am interested in studying small things that make a big impact in the ocean. Right now for my master's research at the University of San Diego,
  • by oceanbites 2 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Gabby Stedman. Gabby is interested in interested in understanding how many species of small-bodied animals there are in the deep-sea and where they live so we can better protect them from
  • by oceanbites 2 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Shawn Wang! Shawn is “an oceanographer that studies ocean conditions of the past. I use everything from microfossils to complex computer models to understand how climate has changed in the past
  • by oceanbites 3 months ago
    Today we are highlighting some of our awesome new authors for  #WriterWednesday  Today we have Daniel Speer! He says, “I am driven to investigate the interface of biology, chemistry, and physics, asking questions about how organisms or biological systems respond
  • by oceanbites 3 months ago
    Here at Oceanbites we love long-term datasets. So much happens in the ocean that sometimes it can be hard to tell if a trend is a part of a natural cycle or actually an anomaly, but as we gather more
  • by oceanbites 4 months ago
    Have you ever seen a lobster molt? Because lobsters have exoskeletons, every time they grow they have to climb out of their old shell, leaving them soft and vulnerable for a few days until their new shell hardens. Young, small
  • by oceanbites 4 months ago
    A lot of zooplankton are translucent, making it much easier to hide from predators. This juvenile mantis shrimp was almost impossible to spot floating in the water, but under a dissecting scope it’s features really come into view. See the
  • by oceanbites 5 months ago
    This is a clump of Dead Man’s Fingers, scientific name Codium fragile. It’s native to the Pacific Ocean and is invasive where I found it on the east coast of the US. It’s a bit velvety, and the coolest thing
  • by oceanbites 5 months ago
    You’ve probably heard of jellyfish, but have you heard of salps? These gelatinous sea creatures band together to form long chains, but they can also fall apart and will wash up onshore like tiny gemstones that squish. Have you seen
  • by oceanbites 6 months ago
    Check out what’s happening on a cool summer research cruise! On the  #neslter  summer transect cruise, we deployed a tow sled called the In Situ Icthyoplankton Imaging System. This can take pictures of gelatinous zooplankton (like jellyfish) that would be
  • by oceanbites 6 months ago
    Did you know horseshoe crabs have more than just two eyes? In these juveniles you can see another set in the middle of the shell. Check out our website to learn about some awesome horseshoe crab research.  #oceanbites   #plankton   #horseshoecrabs 
  • by oceanbites 7 months ago
    Feeling a bit flattened by the week? So are these summer flounder larvae. Fun fact: flounder larvae start out with their eyes set like normal fish, but as they grow one of their eyes migrates to meet the other and
  • by oceanbites 7 months ago
    Have you seen a remote working setup like this? This is a photo from one of our Oceanbites team members Anne Hartwell. “A view from inside the control can of an underwater robot we used to explore the deep parts
  • by oceanbites 8 months ago
    Today is the day of  #shutdownacademia  and  #shutdownstem  and many of us at the Oceanbites team are taking the day to plan solid actions for how we can make our organization and the institutions we work at a better place
  • by oceanbites 8 months ago
    Black lives matter. The recent murders of Ahmaud Arbery, Breonna Taylor, and George Floyd have once again brought to light the racism in our country. All of us at Oceanbites stand with our Black colleagues, friends, readers, and family. The
WP2Social Auto Publish Powered By : XYZScripts.com