You may or may not have read my very early postings about Zombies in Nature last October. Keep that story in mind while I tell you this one.
I have always dreamed of climbing into a rainforest canopy where I could bask in the diversity that is invisible from a ground walker’s perspective. The problem is that there is no easy way to achieve this dream. Old growth rainforest trees are huge, and the canopies can be 30 metres or higher.
Margaret Lowman published a book called Life in the Treetops (2000) where she describes her pioneering efforts to do biological research in rainforest canopies. They tried all sorts of things to get up into the canopy: single ropes, pulley systems, canopy cranes (one day I’ll get up in one of those, mark my words!), and even a giant raft carried by a blimp in the African Congo (here’s a link to a description of a similar program in Madagascar).
So you can imagine, when I was told that we were going to take the students into the canopy in Corcovado National Park, I could barely contain my excitement. Our canopy trip was limited to two platforms, 19 m high, established on mature trees about 50 m apart, and the cable connecting them. To access the first platform, we climbed a narrow cable ladder and, at the top, we connected our harness to a cable and pulled ourselves to the other platform (and/or pushed off the first tree as hard as we could so that we rocketed through the canopy at high velocities).
Our guide, Daniel, patiently watching a student pull herself along the cable.
I was so excited, I rocketed up that ladder like a squirrel (or a monkey! or a squirrel monkey!!). Heights do not bother me, and I am if not a skilled, at least a somewhat experienced climber.
Our amazing tico guides were Daniel and Josue, who are professional tree climbers and rope technicians (they also work in a theater company where they “make Peter Pan fly around”):
Daniel, looking out for us
Josue (Handsome tico guides are one of the unexpected perks of being a field biologist .)
Josue and Daniel moved so gracefully on the wires! They were like monkeys. I asked Josue about it and he called Daniel a “mono cariblanco” (literally a white faced monkey, but it is also the common name of the locally abundant White-faced Capuchin).
I was disappointed that some of the students were not as thrilled as I was:
A student napping 19 m high in the rainforest canopy.
I loved hanging off backwards, with nothing but a single rope connecting my waist harness to the side wire on the platform. I wanted to see everything. And guess what I saw (ignoring the Spider monkeys and capuchins, they’re boring right?)?!
A zombie ant!
The fungus is Ophiocordyceps unilateralis and it is infecting a carpintero (carpenter ant) Camponotus sericeventris.
The ants are carpenter ants, so they would never crawl out “on a limb” (so to speak, haha), like this without a fungus controlling their brain. The fungus then makes the ant bite onto the edge of the leaf so that it won’t fall off. Then the fungus grows out of the ant’s head and spreads its spores over the forest (like snow!).
I contacted the expert on zombie ants (David Hughes) and he informed me that the only other time a zombie ant was found so high above the ground was an ant found 60 m high in a Bornean rainforest. (me = jealous)
The one I found was the neotype for the fungus (i.e. the fungus was first described on Camponotus sericeventris by Tulasne in 1865) and since that time, there has been some discussion about separating it into multiple species. It is possible that a separate Ophiocordyceps fungus infects each different species of Camponotus ant. They certainly have different morphologies!
Check out these different Ophiocordyceps morphologies on different carpenter ants (all of the following images are from Evans et al 2011):
On Camponotus rufipedis, Evans et al 2011
On Camponotus balzani, Evans et al 2011
On Camponotus melanotici, Evans et al 2011
On Camponotus novogranadensis, Evans et al 2011