A small sample of different stages of the structure as well as various
surfaces that they were found on during this research trip. Some are
pristine and new, while others have barely left a trace. Photos: Courtesy Lary Reeves & Ariel Zambelich/WIRED
Entomologist
Phil Torres takes a photo of one of the first structures the team
discovered on this most recent trip on his iPhone, using his finger to
show scale. Most were on cecropia trees (as shown here), while others
have been spotted on other plants, like bamboo. Photo: Ariel Zambelich/WIRED
Entomologist
Lary Reeves inspects a dry stem of ginger with one of the enigmatic
structures while the rest of the team looks over his shoulder. Photo: Ariel Zambelich/WIRED
One of the structures, found on a bamboo stem. Photo: Ariel Zambelich/WIRED
To
better understand what has been creating these mystery structures, Jeff
Cremer (left) and Phil Torres take extreme macro photographs of a
structure on a tree on Fish Pond Island. Photo: Ariel Zambelich/WIRED
A
structure, found on a tree, with a ruler held to measure scale. So far,
the tiny structures average about a half-centimeter in diameter. Photo: Courtesy Lary Reeves
Using
a modified bobby pin, Lary Reeves and Phil Torres pull a broken "spire"
off the tree so they can photograph it more closely and attempt to see
what's stored inside. Photo: Ariel Zambelich/WIRED
An extreme macro shot of the structure's center spire, from above. Photo: Courtesy Jeff Cremer/PeruNature.com
As
they look over samples, Phil Torres, Lary Reeves, and Geena M. Hill
discuss potential theories in Reeves' room at the Tambopata Research
Center. Photo: Ariel Zambelich/WIRED
Samples
of the structures, stored under drinking glasses in Reeves' room at the
research center, that were found on several different plants, including
cecropia, bamboo, ginger, dead leaves, live leaves, and earlier in
2013, a tarp. Photo: Ariel Zambelich/WIRED
A
macro shot of the underside of a toppled spire. The team hypothesized
that the two curved objects inside (one more white, one more yellow)
might be eggs of some sort. Photo: Courtesy Jeff Cremer/PeruNature.com
As
Jeff Cremer looks on, Phil Torres shows naturalist and rainforest guide
Marlene Huaman a view of one of the spires under a microscope, which
they borrowed from macaw researchers at the facility. Photo: Ariel Zambelich/WIRED
A
silk spire is gently taped to a slide for viewing under a microscope.
The team hoped they might be able to witness something hatching so
they'd know what kind of organism may have built the structure. Photo: Ariel Zambelich/WIRED
Notes on a napkin list the questions the team hoped to find help in answering. Photo: Ariel Zambelich/WIRED
Though
not far from the research center, the island is only accessible by
canoe. The journey proved somewhat harrowing in the dark, especially
after days of heavy rain. Photo: Ariel Zambelich/WIRED
Phil Torres, Lary Reeves, and Geena M. Hill collect a dried leaf with a structure on it. Photo: Ariel Zambelich/WIRED
One
of the prime suspects is a spider that camouflages its nest with the
corpses of its prey. Here, scientists inspect one of the nests, tucked
at the base of a node of bamboo. On the other side of the stem is a
structure. Photo: Ariel Zambelich/WIRED
A
close-up of the corpse spider in its nest, covered in the remains of
ants and various smaller arachnids. This is one of two spiders the team
is closely investigating right now. Photo: Courtesy Jeff Cremer/PeruNature.com
TAMBOPATA, Peru —
After six months of speculation, we finally know
what’s building these bizarre silk structures in the Amazon: a spider!
But its precise identity is still a mystery that scientists are
scrambling to solve as I write this.
Last week we followed these spider-hunting scientists, led by entomologist
Phil Torres,
deep into the Amazon rainforest as they attempted to find the tiny silk
towers and figure out where they came from. It has not been an easy
case to crack.
“
With a lot of other weird mysteries, once you make an observation of
some sort, spend enough time out there, the pieces kind of fit
together,” said Torres, a graduate student at
Rice University. “
I’m
surprised by how difficult this one is to solve.”
The bizarre structures first surfaced on the internet late this summer, when graduate student
Troy Alexander posted photos to
Reddit and
Facebook, hoping that somebody could tell him what the structures were. He had discovered them on a small island near the
Tambopata Research Center, deep in the Peruvian Amazon.
Made out of silk, the intricate constructions have two parts: a tall,
central tower, and a circular fence that’s about 6 millimeters across.
Back then, we asked as many entomologists as we could find, but
no one had any idea what the structures were, or what made them. Until now.
Before sunrise on Dec. 10, Torres’ team went to the same small
island. As the skies brightened and the mists lifted, they started
walking through the forest. A half-hour later, Torres had spotted the
first of the tiny towers. Much smaller than he had expected, the
structure was on the bark of a
cecropia tree, nestled near some
branches.
“
It’s so weird!” Torres said.
“What the hell is that small?”
Within 20 minutes, the team had found four more of the tiny
structures.
Over the next few days (and nights), return trips to the
island brought the total number spotted to somewhere around 40. Half of
the structures were built on cecropia trees. Many were on bamboo. A few
were on leaves. And, most them appeared to be in clusters containing
between two and six structures.
“
The one thing that is consistent is that they are in clusters,” said
Geena M. Hill, a research assistant at the
Florida Museum of Natural History.
The team got help from super high-res photos snapped by wildlife photographer
Jeff Cremer, who is also the marketing director for
Rainforest Expeditions,
which manages the lodges where the scientists stay. Cremer often
accompanies Torres on his jungle hunts, to take photos.
His close-up
images captured on the island revealed that tiny mites were crawling
inside and on the fences. At that point, the mites were either an
intriguing clue or a confusing observation, since most mites don’t make
silk.
A more helpful observation came from one of the towers the team
studied early on that had been knocked over.
Super high-res photos
revealed what appeared to be a ruptured egg at its base – perhaps a hint
that the tower could be an elaborate egg sac. But that didn’t make much
obvious sense either.
“
Why not lay more than one egg?” asked
Lary Reeves, an entomologist and conservation biologist at the
University of Florida.
Reeves and Torres collected some of the structures and brought them
back to the research center. They isolated the towers from one another,
took measurements, and waited for something to hatch.
Additional photos
taken at the lodge showed small sacs consistently concealed within the
base of the towers, and more small mites crawling around or stuck in the
fences.
Based on the silk the structures were made from, the team ruled out
butterflies, moths, and fungus as the source. But the problem was, the
team couldn’t rule anything in.
For six days, Reeves, Torres, and Hill watched the tiny towers, all the while considering different hypotheses.
They debated whether the structures could have been made by mites
(not too likely, given how small the mites are), or if the fluffy, fine
silk pointed toward a spider (yes). They questioned whether the sacs
were eggs at all. Maybe, Reeves suggested, they were looking at a
structure called a
spermatophore — a type of gift containing sperm and
nutrients that some insects and spiders exchange during mating. Could
these structures be the work of the huntsman spiders the team kept
seeing on tree trunks? It was hard to say. Every time a hypothesis began
to gain traction, another observation would swoop it and kill it.
Finally, on Dec. 16 as the scientists were preparing to leave the
rainforest without an answer,
two of the eggs hatched and Torres saw two
tiny spiderlings running around the base of the structures. “
We were
excited about that but still hesitant,” Torres said, noting that most of
their hypotheses so far had fallen through.
But the next day, a third egg hatched and produced another small
spider. “
That really confirmed it for me,” Torres said. “
Anything we saw
crawling in there had to have come out of the structure.”
One of the three hatched spiderlings. Photo: Courtesy Jeff Cremer/PeruNature.com
Now, even though the team is sure that they’re looking at some kind
of intricate spider nursery, they’re still confused. For starters,
a
spider laying only one egg in a particular spot is exceptionally rare.
“
Traditionally, the female will lay a bunch of eggs, wrap it up very
well, sit, and protect it,” Torres said. “
This is kind of the opposite.”
And the amount of parental investment in the structures is immense, considering the single spiderling inside.
Then there’s the question of the spider’s identity. It could be a
jumping spider – the spiderlings’ body shape resembles the
Salticidae
family, and they have two giant eyes, resembling a jumping spider’s
adorable head. But the rest of their eyes aren’t quite in the right
place.
It’s also possible the structures could be the work of a spider with a
dark side.
Near some of the clusters, the team saw several spiders that
camouflage their nests with the corpses of their prey, such as ants and
smaller spiders. Could the small spiderlings grow into these crazy
corpse spiders? We’ll have to wait and see, as Torres and his colleagues
continue their investigation.
