About 50 million years ago, a group of ants started doing something that only
three other types of animals, including humans, ever have. They started growing their
own food. And about 40 million years after that,
some of these fungus-farming ants started growing their underground fungus
gardens by feeding them leaves that they collected by doing this. Recently I was
given this colony of leafcutter ants, Atta cephalotes, and these are
some of the most interesting and, actually, most well studied ants on earth.
I don't currently have any research projects on these, but if there's one
thing I'm interested in, in science, it's fine scale details of animal behavior. So,
i've been filming one tiny little aspect of what they do throughout their lives
and that's how they actually cut leaves off of trees. In a day a mature leafcutter
ant nest can cut and gather hundreds of thousands of leaf fragments.
Once an ant finds a suitable leaf and begins cutting it can recruit its nestmates to the leaf with a vibrational signal.
It makes this signal by rapidly raising and lowering its abdomen while cutting the leaf.
Sending vibrations through the jaws into the leaf and down the stem to nearby
nestmates. The ant does this by moving its abdomen at this point here, scraping
the series of microscopic grooves called stridulatory organ and producing a
series of chirps at a frequency of one kilohertz. Leaf cutting isn't the only
time these ants stridulate though. What you're hearing now are recordings made
during digging, which is another context where stridulation also works as a
short-range recruitment signal. During leaf cutting these chirps vibrate the
mandible while it cuts. By vibrating the mandibles and by using the front foot to
pull up on the leaf edge, cutting workers actively stiffen the leaf so they can
make a smooth, easy cut. Ants cut semicircular wedges out of the leaves by
anchoring their legs on the edges and surface while rotating their bodies
during cutting.
Slicing through a leaf involves piercing with a leading mandible and pulling a
fixed cutting mandible through the leaf.
Either mandible can function in either role, slicing through the leaf or
advancing the path of the cut. Watching this happen from below, the cutting
mandible slices and tears through the leaf as the ant uses the bite of the
other jaw to pull it along.
All of this is powered by massive muscles connecting to the jaws that
account for 50% of the weight of the head and 25% of the ant's total body
mass. All of this leaf cutting is just the first step in feeding a living
garden of fungus found inside the nest. A garden that is continually grown over a
decade or more of a colony's life, supporting one of the most advanced
animal societies on earth. So, cutting leaves off trees is a tiny little
fraction of what these ants do. There's so many more details. I mean even before
that leaf fragment is fed to the fungus there's another round of cutting
and cleaning that happens inside the nest. So this video has been all about
ants that make their living from trees, and trees are pretty important to us too.
And you might already know that across YouTube right now there's a campaign
called #teamtrees which is calling for people to support forest restoration
efforts by donating to the Arbor Day Foundation. I think this is a great idea
and a way we can all do something to support healthy forest ecosystems across
the world. So what I'm doing is I'm gonna donate 100%, all of the lifetime ad
revenue that's ever been generated by this channel. Which happens to be a
hundred and seventy eight dollars. And I'm gonna do that through teamtrees.org.
I think it's only appropriate to give whatever this channel has made back to an
organization that supports the natural world. So I encourage you to go to
teamtrees.org and make your donation yourself today.