The incredible "ear stones" of fish


40 Responses to “The incredible "ear stones" of fish”

  1. Antinous / Moderator says:

    Otolith has an ugly sister called sialolith. Gross picture at link.

  2. rockthatroll says:

    I used to study otolith formations as a grad student.

    The rings are formed by alternating deposits of protein and calcium carbonate. In tropical fish it is harder to see yearly rings as those usually correspond to seasonal temperature changes. However, it’s possible to see rings corresponding to lunar cycles and even night/day cycles in certain fish.

    Some researchers use zebrafish to study otoliths particularly because they are clear during early development. This allows the researcher to study while the fish grows. However, I won’t lie, most of these fish are also killed during or at the end of the experiments.

    This procedure is called canalith repositioning. Basically, otoconia (mammal’s version of the otolith) are used only for linear acceleration (up, down, forward, reverse, gravity) and when they get displaced they can come into contact with the hair cells responsible for angular acceleration (tilting side to side or turning our heads). Canalith repositioning moves these errant otoconia away from the hair cells they’re disturbing. Vertigo is pretty unpleasant. I’m sorry she has to suffer through it so often.

  3. arborman says:

    Ah, memories. I spent a few months on a Polish factory ship cutting the otoliths out of fish skulls by the hundreds. That and playing chess and drinking vodka.

    Good times, good times. Except for the fish of course.

  4. Takuan says:

    oooooh! I wanna make a canalith repositioning unit. It will involve large rocket motors, lots of room and bacon.

  5. jimkirk says:


    230 decibels? That can’t possibly be right.

    Don’t forget, this is under water, much higher SPL possible than in air.

  6. avraamov says:

    instead of growing their own otoliths, crayfish absorb sand particles into their statocycts. there’s an oft-tried experiment whereupon the biologist replaces the sand in the crayfish’s tank with iron filings, which are then absorbed as otoliths…

    “during the first 24 h the motor activity of the animals increased and was accompanied by frequent strong beats of antennulae on water; animals tried to go away from the magnet attached to the aquarium wall and to hide in a shelter; by the day 10—12, there appeared signs of adaptation to the action of magnet; the animals spent most time near the wall with the magnet and were clinging close to it. If the magnet was moved the animals not only slipped to their side but also rotated around their longitudinal axis. The eyestalks also started moving.”

  7. NJ says:

    Suggest a revision of the words “and maintain inertia”.

    From the essay:

    “…they orient us in the world, since they work as tiny inertial references…”

    I maintain inertia mostly on weekends.

  8. SomeGuy says:

    Do fresh water fish have otoliths as well? I sometimes find rather large remains of Muskellunge and Northern Pike washed up on the shore by my home and it would make for a fun teaching opportunity with my grandson.

  9. tubacat says:

    This is so cool — many years ago, I bought a pair of earrings somewhere near the ocean (Monterey?), and when I asked what they were made from, the vendor said “the ear bones of a cod fish.”

    See picture:

    It’s not that I didn’t believe her – I did – but I didn’t know that fish even had earbones…And this was way, way before you could look up something like this on Wikipedia!

  10. Mazoola says:

    @#13 Moriarity – Snapping (and presumably mantis) shrimp can also generate acoustic pressures in excess of 200 db.

    Haven’t been able to determine what one finds in the ears of such shrimp — presumably not much.

  11. Anonymous says:

    YAAAAY, The Kircher Society is back!

  12. SomeGuy says:


    Thanks for the pic. It should be interesting to try it out though the fish that I find on my beach aren’t nearly as fresh looking as the specimen shown here and I’d wager they’re more aromatic as well. Fortunately, my grandson is at the age where gross and smelly just makes the activity all the more desirable. :-)

  13. Anonymous says:

    It would be neat if there were a pocket-sized otolith identification chart to address fish fraud. Of course, this only works if you get the head, but it would be cheaper than a DNA test.

  14. Anonymous says:

    #25 indeed they do.

    My favorite is when they use trace elements, like minute amounts of pollutants, or even temperature changes to be able to tell where the fish lived during their lives. Sadly, most fish are not yet wearing GPS devices, which would make them much easier to manage.

  15. Moriarty says:

    “Snapping (and presumably mantis) shrimp can also generate acoustic pressures in excess of 200 db.”

    Well that’s 200. 230 is 1000 times as loud as 200. From Googling, the only things I found at 230 decibels were massive towed navy sonar arrays (which drown out whales’ communication and echolocation dozens of miles away), and the hypothetical sound standing under a Saturn V.

    (Not trying to be nitpicking. It was just an incredible claim.)

  16. Anonymous says:

    I have collected / murdered probably thousands of fish for their otoliths (for Science!). Definitely some Macbeth moments afterward trying to wash your hands of the guilt (and the fish goo).


  17. stegodon says:

    Just passing through

  18. Takuan says:

    how about a torpedo that hits Mach 1? Underwater?

  19. wylkyn says:

    I remember the first time I got a bad inner ear infection. Woke up in the middle of the night and the entire room was spinning. I had no idea what was going on, but it scared me pretty badly. I couldn’t stand up at all.

  20. Talia says:

    Pity you have to kill the animals to get this data. Makes it a rather destructive hobby. If, say, it were kittens this hobby revolved around, people would have a conniption.

  21. Takuan says:

    I wonder… what energies are required…could dolphins be using lithotripsy to hunt? I mean specifically. Which also makes me wonder if one day GMO cetaceans could do your kidney stones.

  22. Takuan says:

    “Bottlenose dolphins have the ability to create booms exceeding 230 decibels, mainly as a hunting weapon to stun fish.” anyone examine the otoliths of the prey? Or fragments thereof?

  23. Anonymous says:

    Santa’s Knee here.

    @#4 Talia,

    As one who only hunts kittens as a food source, I have no problem with the ethics of this article.

    As long as one eats one’s kill, do as you wish for science.

    PETA tried to fool me with that whole “Sea Kitten” stuff, but it was just whargarble – nothing can compare to the taste of fresh kittens straight from the dragnet (I support hobo-safe netting practices, btw).


  24. Anonymous says:

    Does this mean that tossing them across a market is cruel, or is that now just throwing rocks?…

  25. Clemoh says:


    “Should you have occasion to tonsure a snapper or sea-bass”

    This would most likely be after you CAUGHT the fish to EAT the fish. I imagine that’s why the author chose two edible and very tasty species.

    Some of us eat fish, but few of us eat the heads. Why not do a little investigating?

  26. Ugly Canuck says:

    Well most don’t eat them, but some do:

  27. Chorske says:

    My girlfriend sometimes has horrible dizzy fits- she says it feels like the room has suddenly flipped upside down. She had a horse-riding accident in her late teens that, in addition to killing her sense of smell for more than a year, knocked a (some?) small piece(s?) of her “ear stones” free of the matrix in which they are normally embedded. Every now and then, one of dislodged stones ‘bumps’ the sensitive hair cells (the “carpet of delicate hairs” Joshua Foer mentions above), and it makes her feel like her world has suddenly lurched upside-down. It’s horribly unpleasant.

    The treatment involves having a specialist suddenly accelerate your head forward while carefully cradling your head and neck in their arms. It looks bizarre, it’s definitely lo-tech, but it works. Apparently the acceleration moves the dislodged stones away from the hair cells.

  28. Chorske says:

    Also- I work with fish, and I have looked at thousands of these things. They’re beautiful, and as unique as snowflakes, but unlike many of my colleagues, I wouldn’t want to count their growth rings for a living. I have found that by the time you’ve counted your hundredth set of growth rings (and don’t forget you need to do replicates of each count for quality control), the novelty has faded.

    Still, they are beautiful, and they make interesting jewelery:

  29. slgalt says:

    Chorske, here is a DYI version of the Epley Maneuver for vertigo caused by “ear stones.”

    You have to know which ear it is first (Dix-Hallpike test, which looks just like the first position in vid).

  30. Moriarty says:

    230 decibels? That can’t possibly be right.

  31. Talia says:

    Mr. Knee: I agree. Nothing beats a fresh grilled kitten fillet on a bun, with ketchup. And a side of fried mice.

  32. Anonymous says:

    Plague Host is rather a nifty name for a spammer

  33. elendae says:

    I used to collect these as a kid. We called them lucky stones.

  34. Anonymous says:

    Friend of mine does this for a living, a marine biologist doing her dissertation on otoliths in rockfish. She’s hot too.

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