you're reading...


The Hitchhiker’s Guide to the Galax-Sea

Van de Vijver, B., Robert, K., Majewska, R., Frankovich, T. A., Panagopoulou, A., & Bosak, S. (2020). Geographical variation in the diatom communities associated with loggerhead sea turtles (Caretta caretta). PloS one, 15(7), e0236513.

The Hitchhikers and their Host

A loggerhead sea turtle. Image credit: Creative Commons

Sea turtles are one of the most well-known ocean reptiles. They a graceful swimmers that can be found all over the world, and are inextricably linked to many healthy ocean ecosystems. There are several species of sea turtles including green sea turtles, loggerhead sea turtles, leatherback sea turtles, and olive ridley sea turtles, just to name a few.

Just like humans have microscopic species living on and within our body, called our microbiome, all species of sea turtles can grow and carry a unique set of organisms on their shells and skin. These hitchhikers, or epibionts, adhere to a sea turtles’ shell similarly to the way they would a rock or coral on the ocean floor. A specific type of phytoplankton, called a diatom, is one of the single-celled organisms most commonly found on sea turtle shells. When the phytoplankton are really dense, the can form a film-like substance that can cover the skin and shell of the sea turtle.

A few species of diatoms. Image credit: Creative Commons

There are around 5,000 known species of diatoms, and their geographical range can vary from just a couple of miles across to worldwide. Turtles are a highly migratory species, which led Bart Van de Vijver and his fellow researchers to ask the question: Can you tell where a sea turtle has been from what it’s carrying on its back?

I Scratch Your Back, You Scratch Mine

Van de Vijver and his team decided they wanted to focus their studies on loggerhead sea turtles in four areas of the world – Croatia, Greece, South Africa, and Florida (USA). In each of these locations, five turtles were randomly selected to get their shells sampled for diatoms. Turtles from Greece and South Africa had their shells scrubbed using a single-use toothbrush, turtles from Croatia had their shells scraped with a sharp tool (don’t worry – this didn’t hurt the turtles!), and the turtles from Florida had their shells swabbed with Q-tips.

These samples were then brought to the lab and analyzed to figure out what species of diatoms were on the turtles’ shells. The diatoms were photographed using an Electron Scanning Microscope, which is a special kind of microscope that can provide detailed images of the surface of cells. Scientists were then able to tell what type of diatoms were present on each turtle’s shell.

What Did They Find?

The loggerhead turtles that these scientist studied had over 400 different species of diatoms on their shells and skin. They found a unique array of species, including species that are endemic to, or can only be located on, the backs of turtles. It also seemed that the way that they sampled the turtles had a major effect on the diversity of life that they saw. Florida sea turtles had the least amount of biodiversity. Most of the species were not particularly “sticky”; they were the species that would have been easily knocked off the shell with the cotton swab. On the other hand, the Croatian turtles had higher biodiversity, which the scientists attributed to the knifelike tool they used to scrape samples off the shells.

A sea turtle grazing on sea grass. Image credit: Creative Commons

Even though the biodiversity of diatoms in the Florida turtles was lower than that of the others, Van de Vijver and his team still found significant differences between the makeups of species on the turtles at all locations. These turtles are grazers, mostly eating sea grass off the ocean floor. The scientists hypothesized that when these turtles turned up the sand by pulling out the grass, many diatoms that were in the sand, and specific to the region they were in, would stick to the shells of the turtles as they continued to move along. This answered their original question; they were able to figure out where a sea turtle lived based on their hitchhikers.

Sea Turtles: an Endangered Species

Why should we care about these turtles and their hitchhikers? The reasons are twofold. As a reminder, diatoms’ habitat ranges can be really limited. These turtles can act as a vector to bring species of diatoms to new areas. Since diatoms can reproduce asexually, a single cell in a new location could expand a diatom’s habitat range. Secondly, turtles are an endangered species, so scientists are constantly trying to improve way to ID and track individuals. Looking at the makeup of diatoms for individual turtles could help scientists determine their home turf, and even possibly help identify a specific turtle. Looks like these hitchhikers aren’t complete freeloaders after all!



No comments yet.

Post a Comment


  • by oceanbites 2 months ago
    Happy Earth Day! Take some time today to do something for the planet and appreciate the ocean, which covers 71% of the Earth’s surface.  #EarthDay   #OceanAppreciation   #Oceanbites   #CoastalVibes   #CoastalRI 
  • by oceanbites 3 months 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 3 months 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 5 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 5 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 5 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 5 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 6 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 6 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 7 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 7 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 7 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 7 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 8 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 8 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 9 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 9 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 10 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 11 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 11 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 
WP2Social Auto Publish Powered By : XYZScripts.com