you're reading...


Whale earwax: a hearing aid & time capsule

Created by Megan Chen, based off an idea by Justine Bassett

Created by Megan Chen, based off an idea by Justine Bassett


Let’s Dive Right In

Whale earwax: a topic that has probably never crossed your mind. The existence of whale earwax should not be overwhelmingly surprising, considering that like us, they are mammals. However, because whale ear openings are tiny compared to the rest of their body (e.g. blue whale ear holes range from the size of a pencil point to eraser tip in diameter!), it may be that whale ears are not obvious enough to prompt deep thoughts about whale earwax.

All cetaceans (whales, dolphins and porpoises) produce earwax. In some species of baleen whales and in sperm whales, whale earwax can build up in layers over time to form an “earplug” that sits in the ear canal.

Humpback whales hanging out with their earwax (Credit: Ed Lyman, NOAA National Marine Sanctuaries)

Image 1: Humpback whales hanging out with their earwax (Credit: Ed Lyman, NOAA National Marine Sanctuaries)

Whale earplugs are extremely valuable to whale survival for two main reasons:

  1. They are a built-in hearing aid:

Whales rely more on their sense of hearing than sight. They use sound for navigation, foraging for food and for communication, useful for finding mates. Whales can communicate and hear over thousands of miles! However, whales do not hear like land mammals do because water is five times more dense than air. If whale ears were filled with air like our ears, there would be a mismatch between how sound travels in water and how it travels through whale ears—this is called acoustic impedance mismatch. The density of the earwax that sits in the ear canal (external ear) is a similar density to water, thereby allowing sound to travel through the ear canal into the inner ear unimpeded.


  1. They are a time capsule holding years in ears:

If you slice a whale earplug lengthwise, it will reveal alternating light and dark layers. Light layers are associated with periods of feeding because there are more lipid droplets from prey interspersed between wax cells. Dark layers are associated with migration or when the whale is not feeding. Counting the layers represents an accurate proxy for age, although different species of whales excrete earwax at different rates.  In blue whales, one light layer and one dark layer represents one year of life.


Image 2: Unidentified earplug from the Smithsonian’s National Museum of Natural History collections. Note the light and dark layers. (Credit: Megan Chen)

This technique is not new. Scientists have been using earplugs to age whales since the 1950s. In fact, many earplugs were collected between the 1950s-1960s at “whaling stations” when commercial whaling for meat, oil, blubber and baleen was common. A few museums, including the Smithsonian’s National Museum of Natural History (NMNH), hold collections of earplugs from this time. To some, these collections may seem redundant and scientifically useless after all the layers have been counted. However, science is not done with whale earplugs just yet!

Recent advances in technology have allowed scientists to chemically analyze traces of compounds in each waxy layer of an earplug, opening a whole new dimension of research possibilities within an earplug collection. Fun fact: removing each layer is painstakingly hard requiring a microscope, a steady hand, many hours and many cups of coffee.


An Example: Decoding the Life History of a Blue Whale

Using modern techniques, Dr. Stephen Trumble and co-researchers were able to quantify lifetime levels of two hormones and forty-two contaminants from a single 10-inch earplug obtained from a male blue whale that died in a ship strike.  It is worth mentioning here that in 1986, a moratorium on commercial whaling came into effect, so nowadays (with very few exceptions), earplugs can only be collected from whales that have died from ship strikes, entanglement in fishing gear or strandings.


Image 3: Graph depicting hormone levels throughout a male blue whale’s life. (Data from Stephen J. Trumble, PhD)

For this male blue whale, results showed that he reached sexual maturity around 10 years old, and felt the most stress shortly after—finding a mate is never easy (see Image 3).  Exposure to pesticides and flame retardants that have been banned for several decades were highest when the whale was 0-6 months old, showing maternal transfer, and chemical persistence. Mercury did not follow the same trend.  Instead, it had lower maternal transfer, but two later peaks that could be the result of feeding in highly contaminated industrial areas. To date, this is the only earplug fully analyzed in this way, although there are certainly more in the works.


So what?

Studying earplugs gives us a chronology (± 6 months) of life history information that was previously unavailable.  This is significant because whales are part of a healthy ecosystem, they have cultural significance and they are at the centre of a $2.1 billion ecotourism industry! Unfortunately, many whales–including blue whales–are endangered due to historical hunting, and are currently facing challenges to recovery such as noise pollution (it makes communication difficult), entanglement in fishing gear, etc. By examining stress levels and levels of contaminants of current whales, then comparing them to historical baselines using museum collections, we can assess what impacts humans have had and currently have on whales and marine ecosystems. This type of information can then be used to develop management plans to reduce threats, facilitating recovery.

To recap: whales can’t live without their earwax, and perhaps, given their ecological and economic significance, neither can humans.

Image 4: Scientists and tourists on board a whale watching vessel in Skjálfandi Bay, Iceland, admire a surfacing humpback whale. (Credit: Megan Chen)

Image 4: Scientists and tourists on board a whale watching vessel in Skjálfandi Bay, Iceland, admire a surfacing humpback whale. (Credit: Megan Chen)


Shameless promo: I’m developing a self-guided activity for the Smithsonian’s National Museum of Natural History on whale earwax that should be on the floor next month!  If you are in the area, please feel free to come check it out! Also many thanks to Dr. Steve Trumble, Dr. Sascha Usenko of Baylor University and of course, Charley Potter (NMNH) for sharing their research and time, answering countless questions, and generally being awesome!



  1. […] autonomous robots for monitoring fish populations. Wednesday is a double header: Megan will look at whale earwax and how that affects their perception of sound. Gordon will discuss a paper on how fish can find […]

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 4 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