Tripod fish: a fish that stands

Video link

The other day, I went through the Deep Sea exhibit at the Natural History Museum. Deep Sea ecology is pretty interesting and especially great for the variety and oddness in creatures that dwell there. Case in point are Tripod Fish.

These deep sea beauties have long extensions coming out of their fins (two from their pelvic fins, and one at the back from the caudal fin), such that they are able to "stand still" on the ocean floor. Here they can wait very patiently for prey to come wandering into their vicinity.

Presumably a great way to conserve energy, although it would be interesting to examine whether there is a reason for the stilts being a certain height (i.e. do the crustaceans that the Tripod Fish feed on, prefer to hover at a certain depth, or do currents close to the ground uplift material in a certain way?)


  1. That’s pretty cool, I guess, if you are into that sort of thing.

    The University of Victoria’s underwater robotic exploration team found a rice cooker full of octopus on the ocean floor.

    1. I would love to test your theory by submitting an article on this lovely animal to Conservapedia and observing how many milliseconds it takes for it to be removed. But I only have enough spare time to read BB today…

    2. Hmm. Perhaps it supports the “designed” part, but certainly not “intelligent”. More supportive of the “absurd design,” “irrational design” or “silly design” theories.

  2. When we’ve overfished the other species into extinction, this fish will be renamed “deepwater tilapia” and be found on our plates. Most engaging will be the preparation where the tripod fins are left on, so you can stare at it eyeball to eyeball before taking a bite.

  3. I suspect that it’s about being very very quiet as much as saving energy. In a world that never sees the sun that could be very important

  4. A pity the HDD (presumably for the onboard still camera) was 99% full. If I was flying that ROV, I’d have been snapping away, getting some good stills (And before anyone says anything, yes, I _AM_ an ROV pilot)
    David, after reading the Wikipedia entry, and seeing how it feeds ( ) I’d imagine that it has something to do with the boundary layer effect. In areas of current, there’s often a zone extending a small distance from the bottom where there’s no current, called the boundary layer. I suppose it could be thought of as being like how it gets windier when you’re at altitude? I’d imagine that the pectoral fins/stilts evolved as an adaptation to get it up above the boundary layer where it can be exposed to more prey drifting by; if it waited right on the bottom, it could be waiting a long, long time.

  5. Some possible evolutionary advantages:

    Distance from parasites in the mud;

    Prevents silt cloud that may be caused by large surface settling to silt, or by movement once settled, thereby removing a warning to prey and a signal to predators;

    Removes ground effect (low pressure area under bodies that causes bodies during liftoff to have less lift than expected for locomotor output) thereby improving agility;

    Increased tactile area with distancing from hazards (ten-foot-pole effect), including water movement;

    May augment tip eddies from fins (increasing, decreasing, or re-vectoring) during movement, thereby augmenting pressure differential between opposite sides of the fin;

    May augment pressure wave wake to make fish seem larger or smaller to prey or predators that rely on sensory input from pressure wave sensing (“sonar cloaking”).

    Not an exhaustive list, but what comes off the top of my head.

  6. Chickens have two legs
    And firemen have two legs
    And monkeys have two legs
    But tripods have three legs

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