That’s some tongue


Behold the spectacularly long-tongued glossophagine nectar bat, Anoura fistulata:

i-637ca2695ab40ca81df624a2b3792d1c-anoura.jpg
Anoura fistulata feeding from a test tube filled with sugared water; its tongue (pink) can extend to 150% of body length.

This length of tongue is unusual for the genus, and there is an explanation for how it can fit all of that into its mouth: it doesn’t. The base of the tongue has been carried back deep into the chest in a pocket of epithelium, and is actually rooted in the animal’s chest.

i-2b61d1fb1ab14963a2732fab0816bd67-anoura_anatomy.jpg
Ventral view of A. fistulata, showing tongue (pink), glossal tube and tongue retractor muscle (blue), and skeletal elements (white).

Across the glossophagine nectar bats, maximum tongue extension is tightly correlated with the length of their rostral components, such as the palate and mandible. Although the correlation holds for A. caudifer and A. geoffroyi, A. fistulata falls far outside the 95% confidence interval. Close examination of tongue morphology reveals the basis for this pattern. In other nectar bats, the base of the tongue coincides with the base of the oral cavity (the typical condition for mammals), but in A. fistulata the tongue passes back through the neck and into the thoracic cavity. This portion is surrounded by a sleeve of tissue, or glossal tube, which follows the ventral surface of the trachea back and positions the base of the tongue between the heart and the sternum.

Unsurprisingly, this adaptation co-evolved with the lengthening corolla of a tropical flower, Centropogon nigricans—observations suggest that this bat is the only pollinator of this particular flower.

I’m sure Gene Simmons would be jealous.


Muchhala N (2006) Nectar bat stows huge tongue in its rib cage. Nature 444:701-702.

Comments

  1. says

    Talk about being tied to your food supply, or simply tongue-tied; that is so bizarre. I’ve seen the sword-billed hummingbirds, but the bat’s tongue in the picture has no supporting structure and looks as if it rolled out although I’m sure it’s muscular.

  2. Joshua says

    Wild!

    Don’t woodpeckers or some other species of bird have a similar tongue configuration? Convergent evolution in action!

  3. Berlzebub says

    Carl said:
    Talk about being tied to your food supply…

    Since it was noted that “observations suggest that this bat is the only pollinator of this particular flower.” That would suggest the tie-in is symbiotic. If the nectar bat did not evolve such a feeding method, the plant would have had to evolve in such a way for a different animal or insect to polinate it (or the plant would have went extinct). If the nectar bat is the only pollinator, this gives that species bat a private food source. I would expect it can feed from other plants, but this one may just be its preference.

    -Berlzebub

    PS. There are days when I wish I would have followed my dream to become a scientist instead of an engineer.

  4. says

    Very cool, thanks for posting this.

    If I recall correctly, the woodpeckers with uber-tongues have moved the base of the tongue around the back of the head, rather than down into the chest. Cretinists occasionally pull that one out as yet another “irreducibly complex” adaptation. Will they cite the bats, too?

  5. says

    Ditto that last comment, Berlzebub. I was scared off by how incredibly mundane and pointless the first year biology course was, so I became an engineer. But now I can see the wonders science has to offer, and now engineering seems mundane. Maybe I’m just a “grass is greener” kind of person.

  6. oddjob says

    However, Berlzebub, the trick with this particular kind of biology is researching the matter in a way that provides truly new information instead of yet another just-so story.

  7. Berlzebub says

    It sounds like we’re in the same boat, KA. Ironically, I scored high on science in those ridiculous tests in high school, but low on math. “They” said I wouldn’t be good at engineering, and should go into a science field (become a pharmacist). Part of it was my bullheadedness (is that a word?). I hate being told not to do something.

    Oddjob, that’s why I sometimes wish I would have went into science. The thing I enjoy most about engineering is problem solving, or “putting on my Sherlock Holmes hat”, as I put it. I enjoy finding solutions, and alternate ways of doing things. I just wish I was with a company that was more open to R&D style things. Instead of the “this is how we’ve always done it” philosophy.

    -Berlzebub

  8. Azkyroth says

    *sighs* I wish a certain friend of mine still had some web presence. No doubt she’d have something scandalous and hilarious to say about a creature with a tongue like this… ;/

  9. says

    This length of tongue is unusual for the genus, and there is an explanation for how it can fit all of that into its mouth: it doesn’t. The base of the tongue has been carried back deep into the chest in a pocket of epithelium, and is actually rooted in the animal’s chest.

    That seems like a pretty big divergance from the other members of the genus, to have a whole new tongue storage mechanism. Wouldn’t that be a pretty strong reason to give it a genus of its own?

  10. says

    Yo, why is this a Nature paper? It’s kinda neat, but… um…

    Basically, I’m whining because they rejected my paper. Jerks.

  11. octopod says

    Oh man. Dr. Meyers, I thoroughly approve of your metazoan preferences. Cephalopods, now chiroptera? Awesome.

    This guy’s pretty awesome, too, even as bats go. As fwiffo suggests, though, it seems like a pretty major difference — how confident are they on the relationships/cladistics for these Anoura critters?

  12. David Marjanović says

    That seems like a pretty big divergance from the other members of the genus, to have a whole new tongue storage mechanism. Wouldn’t that be a pretty strong reason to give it a genus of its own?

    That would make the original genus paraphyletic. We don’t like that anymore. These days we value descent over modification in biological nomenclature.

  13. David Marjanović says

    That seems like a pretty big divergance from the other members of the genus, to have a whole new tongue storage mechanism. Wouldn’t that be a pretty strong reason to give it a genus of its own?

    That would make the original genus paraphyletic. We don’t like that anymore. These days we value descent over modification in biological nomenclature.

  14. pluky says

    I’m sorry some of the earlier posters abandoned biology after the intro courses. Unfortunately, there is a lot of specialized vocabulary that has to be assimilated before one can get to the good stuff. And yes, it can be tedious!

  15. Nathan says

    In answer to why this guy doesnt get its own genus, its actually nearly identical to other Anoura morphologically. For example, you can’t tell craniums of A. fistulata and A. caudifer apart. Only the soft tissues (lip, tongue) have diverged; suggesting a very recent evolution! It would be cool to do the molecular work to figure out when it happened…

  16. Nathan says

    Hehe, and in answer to why it got into Nature, it wasn’t easy! They rejected it the first time around… So I say add some nice pictures and resubmit, saurabh
    (After the rejection, I spent nearly a year complaining about other papers I saw in Nature :) )