"Let's go bug-hunting."
Doesn't sound very exciting. Probably won't work as a pick-up line. But now that I've done it – gone bug hunting, that is – I must admit that it's pretty fun.You have to watch your step, though.
Aquatic entomologist Dan Polhemus wanted to catch insects along the main channel of the Mamberamo River today. Since I'm finally getting used to the tipsy canoes, I decided to go along.
We walked down the Furu again to meet the canoe. "Why insects?" I asked Dan. "I mean, out of all the cool animals out there, why did you choose to study insects?" I was trying not to sound incredulous.
|"Insects help scientists understand historical biogeography."
"It's my dad's fault," Dan answered, then explained that his father had moved from a career in chemical engineering to a career in entomology. Dan and his father still work together on entomological research. "Besides," Dan added, "insects do cool things."
For example, insects, like some other taxa, help entomologists track geology; the distribution of bugs can tell a lot about how land masses have formed and moved. The southern part of the island of New Guinea is part of the same land mass as Australia, and the connective land wasn't always under water. So Australia and New Guinea share many species of insects even though they're now separated by the Indian Ocean. On the other hand, the northern part of the island was once several parallel chains of islands that were gradually pushed onto the front of New Guinea. The Solomon Islands were also a part of that chain of islands, so the Solomon Islands and New Guinea share similar insect species. Insects help scientists understand historical biogeography.
|Aquatic entomologist Dan Polhemus dislodges insects from under rocks in order to scoop them up with his net. © Debbie Gowensmith|
Dan handed his net to me, and I stepped into the stream. The water rushed around my calves, and I immediately felt cooler. Dan pointed out the water-striders, easy to spot when the sun reflects off the water. I swung the net, peeked inside, and saw two water-striders sitting at the bottom. I swung again and caught several more. Success is fun!
Some of the dragonflies and damselflies I saw on the way to the canoe are among the most beautiful creatures I have ever seen. As colorful as stained-glass windows, they twinkle in the sunlight. The Neurobasis sp. looks like it's been dusted with green, purple, and blue glitter. The body of one species of Libullid is such a bright, glowing red that I think of Christmas lights every time I see it.
We met the canoe, which took us to the Mamberamo. Once there, Dan held his net in the water as we moved to see what he could pick up. We floated past Dabra and met the Tiri River. The Tiri met the Mamberamo with force, its teal waters tumbling into the Mamberamo's brown. The Tiri was cold, too-a mountain river.
We hopped out of the canoe, and Dan headed toward a pool of orange water separated from the Tiri by a sandy bank. He scooped his net under rocks and over the surface, while I stayed on the opposite bank to take pictures.
When I was ready to join Dan, he called to me, "Watch out for the sand! You've got to move across it quickly!" I walked as quickly as I could in my awkward rubber boots.
||"We're back at Dabra Camp 1 now, and Dan is telling everyone how I wandered into quicksand."|
Not quickly enough.
The ground became boggy, jiggling like Jell-O. My right foot went into what felt like wet cement, and sand covered my boot almost up to my knee. The pressure locked my foot in place. As I struggled to pull out that leg without falling, the left foot began sinking. I was stuck.
Dan had been keeping his eye on me and knew I was in trouble. He ran to the edge of the sand and extended his net toward me. I held onto the net with my left hand, grabbed my right leg with my right hand, and pulled with all my strength. Sloop! Up came my foot, minus the boot. I dislodged the boot and then hopped with one bare foot over the rest of the sand.
"That's how fossils are made," said Dan. "You've no doubt seen quicksand in the movies, but now you know it's real."
I went barefoot for the rest of the day.
|The beautiful Neurobasis sp., which were common around the Furu River. © Debbie Gowensmith|
Back in the canoe on the Mamberamo, we saw stringy white insects zipping over the surface of the water. "Ah, the mayflies are hatching," Dan said excitedly. He explained that a big hatch of mayflies indicates that the river bottom is in good health. "If the sediment is contaminated with chemicals," he said, "then the mayfly eggs die." The local boatman called the bugs kupu-kupu air, or "water butterflies." "By nightfall you won't be able to see the water for the mayflies," said Dan.
As we sped along the river, the surface of the water became whiter and whiter with clouds of skating mayflies. Birds dove again and again to the surface, taking advantage of the plentiful feast.
Bugs do do cool things. Mayflies walk on water. Anisops, also called backswimmers, use hemoglobin like swim bladders to regulate their depth in water. Naucorids, or creeping water bugs, use a fine coating of microhairs to trap bubbles of air. They use the oxygen from the bubbles, which is continually replaced, to live their entire lives beneath the water's surface.
We're back at Dabra Camp 1 now, and Dan is telling everyone how I wandered into quicksand. Everyone is having a good laugh. I wish I had bubble-trapping microhairs so I could sink underwater and never come up, too!
- Reported by Debbie Gowensmith
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