Question:
I've read that some large alligators have special birds that hang out
in their bouths and clean their teeth. The birds make a living on
what they find lodged between the gator's teeth, and the alligators
don't try to eat the birds, because dental floss is hard to come by in
the swamp.
So the questions:
1. Is this really true? What kind of birds are these?
2. How many birds per alligator?
3. Alligators or Crocodiles? Or both?
4. Does the same little flock of birds settle down on one alligator
forever? Or do the birds rotate from alligator to alligator
depending on which one has had supper most recently?
Or is it in between, with Flock A always servicing Alligators
A1..A20 and Flock B always servicing alligators B1..B20?
Answer:
This type of behavior is known as commensalism. It is a fairly common
form of symbiosis, and exists all over the animal kingdom. The specific
case of alligators and birds is unknown to me, but crocodiles have a
couple of bird species that will clean their mouths and backs of food
particles and parasites.
You wondering about zoning or fire codes? I'd guess it depends on how
dirty the host animal is: the filthier, the more opportunity for the
client animal to make a meal, and the more chance that he'll hire on
assistants.
See above. There's the Yangtse alligator and the caiman, neither of
which I know if they have commensal relationships with birds. And the
Ozzie croc, which is a true croc, but which may not have any of the
requisite birds living there.
I don't know. I'm guessing that the birds are more like any birds,
looking for dinner, and will take any croc that offers a cleaning.
Pictures of crocs that I've seen involve the big lizards lying in the
Sun, jaws gaping open, and these white birds hopping in and out of those
death traps with no apparent concern for their safety. The birds also do
croc backs, and hippos, too.
There's an odd Far Side cartoon (perhaps that's redundant) where a
crocodile is saying to his therapist, "You know those birds that are
supposed to clean your teeth. I've been eating them like popcorn."
What sort of concern would you expect to see in a crocodile-dentist
bird? Updating its will? Making sure the life-insurance payments are
paid? Propping a big stick in the croc's mouth?
Call me unimaginative, but I don't see any way to both hop in and out
of a crocodile's mouth and display any concern for ones safety.
A web search yielded the Egyptian plover and the Nile crocodile.
Nothing on mutualism in alligators.
One of my favorite Far Side cartoons features a crocodile talking on a
psychiatrist's couch. The caption: "You know those birds that sit in my
mouth and clean my teeth? I've been eating those guys like popcorn."
