//
you're reading...

Parasitism

Where other bugs fear to tread: seals carry superdiving lice

Study: Leonardi, M. S., Crespo, J. E., Soto, F. A., Vera, R. B., Rua, J. C., & Lazzari, C. R. (2020). Under
pressure: the extraordinary survival of seal lice in the deep sea. Journal of Experimental Biology, 223(17).

Did you know that seals have lice? Just like poorly looked-after cats and dogs, these mammals of the sea are cursed with blood-sucking parasites. Such a predicament begs the question: can seals scratch an itch with their flippers? Scientists are also interested in the seal-dwelling lice because of their daredevil lifestyle.

On land, there are more insects than any other species, but not in the ocean. Saltiness, cold, and immense underwater pressure deter bugs of the world from colonizing the waves. Lice that live on seals are the only insects known to venture under the sea – by hitching a ride with their hosts. A team of researchers in Argentina set out to investigate whether lice can survive their deep-diving trips.

A lousy job

Elephant seals get their name from the large noses of the males. The pups look tiny but don’t be fooled – they weigh at least a hundred pounds. Image source: Wikimedia commons

The scientists traveled to the Natural Reserve of Península Valdés in Argentina, the dwelling place of a large colony of elephant seals. Foraging for fish, elephant seals can dive as deep as two kilometers (1.2 miles). Such quests put the survival skills of their lice, L. macrorhini, to a strenuous test.

At the Natural Reserve, the researchers caught a few (adorable!) elephant seal pups, many of whom were ridden with lice. They then collected some of the parasites, somewhat easing the pups’ burden. Curiously, L. macrorhini died rapidly in the air when removed from their seal hosts, but survived if immediately placed in sea water and allowed to float freely. Some lice were adults and others were nymphs, or immature lice.

Back in the lab, the researchers tried their best to drown the lice. They placed the insects into a hydrostatic pressure apparatus, made from a pressure chamber and a diver tank filled with seawater. The lice were then subjected to increasing amounts of pressure, which mirrored the water pressure that they had experienced when diving with seals. The researchers rescued the lice after ten minutes in the pressure chamber and let them recover for up to two hours, monitoring each louse for signs of life.

Generation gap

The L. macrorhini demonstrated enviable resilience under crushing pressure. Even at the pressure of 200 kg cm−2, which corresponds to two kilometers below the sea surface, all six adult lice lived. All the other adult lice survived equally well at lower pressure levels.

L. macrorhini are lice that infest seals. Nymphs, or juvenile lice, look similar to adult lice but are smaller. Image source: Wikimedia commons

Nymphs, however, did not fare so well. After being put through the pressure of 200 kg cm−2, one-fifth of the young lice perished. These statistics are still pretty impressive, given that most land creatures, including insects, would be unlikely to survive in these conditions. 

Adult lice also recovered from their trials in the pressure chamber much faster. After being exposed to high water pressures that corresponded to the depths of 1.5 and 2 kilometers, mature insects began moving their legs or antennae in under five minutes. Twice as much time was needed for the surviving nymphs to start kicking again. 

The researchers then wondered if the lice survivors could do it again or if their high-pressure tribulations had lethally undermined their resilience. The insects, both adults and nymphs, were put through the pressure chamber for the second time. The adult lice once again did better than their young conspecifics. Unfazed by the second round of high pressure, the mature insects started moving about only after a minute. The nymphs took 1.5-5.5 minutes to recover.

Survival strategy? Scales!

How do adult lice manage to survive such extreme conditions? The researchers speculated that their impressive resilience may come from having a suit of armor. The bodies of some lice species are covered with scales, which may protect the insects under crushing pressure. This would also help explain why adult lice in the study survived better than nymphs, who don’t have scales yet.

L. macrorhini seemed to not mind the lack of oxygen either. They stopped moving shortly after being immersed underwater, which may be a clue explaining their tolerance for hypoxia. If insects slow their bodily processes, they need less oxygen to maintain themselves. This strategy most likely wouldn’t work for land mammals who require massive amounts of oxygen to feed their huge brains, but insects may be able to pull it off – no offense to them. 

The incredible underwater survival of seal lice can reveal why insects have overrun the land but not the ocean. As we strive to solve this puzzle of nature, we should spare a thought for the true heroes of this tale – elephant seals who can’t catch a break from their parasites even underwater.

Discussion

No comments yet.

Post a Comment

Instagram

  • by oceanbites 3 weeks ago
    Not all outdoor science is fieldwork. Some of the best days in the lab can be setting up experiments, especially when you get to do it outdoors. It’s an exciting mix of problem solving, precision, preparation, and teamwork. Here is
  • by oceanbites 1 month ago
    Being on a research cruise is a unique experience with the open water, 12-hour working shifts, and close quarters, but there are some familiar practices too. Here Diana is filtering seawater to gather chlorophyll for analysis, the same process on
  • by oceanbites 3 months ago
    This week for  #WriterWednesday  on  #oceanbites  we are featuring Hannah Collins  @hannahh_irene  Hannah works with marine suspension feeding bivalves and microplastics, investigating whether ingesting microplastics causes changes to the gut microbial community or gut tissues. She hopes to keep working
  • by oceanbites 3 months 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 3 months 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 months 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 4 months 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 4 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 4 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 5 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 5 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 5 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 6 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 6 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 7 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 7 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 8 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 8 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 9 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 9 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
WP2Social Auto Publish Powered By : XYZScripts.com