Northern Queensland Part 2: Sacrificial Leaves, Neurotoxins, Feral Pigs, and the Jacobson's Organ

This is the second part in a series on a trip to the Great Barrier Reef and Daintree Rainforest. See Part 1

After two leisurely days in Port Douglas we crammed into our hatchback once more and turned north to Cape Tribulation. We passed a few small towns but soon entered no man's land, exiting the main road and taking a ferry across the crocodile-infested Daintree River, which cuts Cape Tribulation off from civilization.

The drive to Cape Trib was stunning. A winding road meandered up and down mountains covered in dense forest. At various points the foliage thinned out, revealing views of beaches and the turquoise sea below. I knew we were in the middle of nowhere when my mobile phone lost its signal. (This was a standard occurrence with my old provider, Vodafone. I could be standing in their corporate headquarters and I still wouldn't be able to make a call. Since changing to Telstra the coverage has been so much better so I knew when I lost a signal we were "out there".)

One of our stops on the way north to Cape Trib

View of the ocean from the road in the Daintree.

We checked in to the Ferntree Rainforest Lodge, a collection of stand-alone rooms about a kilometer from where the paved road turned into a dirt and gravel track (if you want to keep heading north, better get yourself an SUV). Then we walked down the road to the beach. At the entrance signs warned us of crocodiles. The water near the shore was a bit murky and it wasn't hot enough to be inviting for a swim, but the beach was beautiful -- palm trees formed a border along the sand, blocking any sign of humans, streams cut to the sea through the forest, mountains rose up in the west. 

We walked along the beach for a while before coming to one of the streams, which cut us off from the rest of the beach. Sharon and I stood there a few minutes while I debated the merits of crossing: on the one hand, I could get to the other side; on the other, I could get eaten. It was a tough call. Ultimately, I decided not to cross (I think the idea of being featured on the evening news under the headline "Dumb American gets eaten by crocodile, despite signs everywhere warning people about crocodiles" was the clincher). We headed back to the lodge for a taco night special they were offering. There's a scientific theorem that postulates the farther away you get from Mexico, the worse Mexican food tastes; we were pretty damn far from Mexico. Some places should just stick with the basics.

Watch out for crocs!

Walking along the beach in Cape Tribulation in the late afternoon.

The tropics!

On Saturday morning Sharon booked a four hour private guided walk through the forest at Cooper Creek Wilderness, a large tract of private property in the Daintree. Our guide for the walk was Neil, a sturdily built man who lives on the property with his wife and kids. After getting his university degree, he spent seven years teaching aborigines in the Tanami Desert in Australia's Northern Territory (and likely learned quite a bit from them as well) before buying the Cooper Creek property, where his family had lived for 26 years. Because it was part of protected area they were very restricted in how they could live -- for instance, all their power was from solar panels or generators because they couldn't bring in power lines from the road.

As we walked through the forest Neil told us its history and shared with us some of its secrets. The Daintree (named for a Mr. Daintree, not a Dain Tree) is the oldest forest in the world, a remnant of when the planet's landmass was a vast supercontinent called Gondwanaland. Its significance wasn't discovered until the 1960s when it became a hot spot for hippies. Around the same time, ranchers bringing their cattle from farther north down to the market at Cairns would let the cattle rest and fatten up nearby. The hippies didn't like the cows destroying the area and often butted heads with ranchers.

One day a rancher found a few cows dying and suspected they were intentionally poisoned, despite the fact that this would be very un-hippy like. He called a veterinarian who discovered a unique seed in the stomachs of the cows. He sent it off to Queensland's agricultural laboratory and the researchers couldn't believe what they were seeing when they did their analysis: it was the botanical equivalent of finding a living dinosaur. All the biologists had been busy studying the 20,000 year old forest south of the Daintree River, and just north of it was a 165 million year old forest.

Logging devastated much of the area before it was declared a World Heritage site. A single 700 or 800 year old tree could bring in $70,000-100,000. But because the network of vines and trees is so dense, to cut down one big tree, you need to cut down all the little trees and vines around it to actually get it to fall, otherwise these informal support structures will keep it standing. Simply replanting isn't a solution because when a big cyclone comes through it will tear down any trees without this support. Cyclones come through about once every seven years  (which means about 24 million cyclones over the life of the forest).

As Neil was giving us this background a Cassowary wandered out of the brush behind him. The Cassowary is a giant bird that looks like a cross between an ostrich and a dinosaur. It's the largest animal in Australia (yes, even larger than Kangaroos in terms of height). It's also endangered, which is why seeing one up close in the wild was so remarkable.

A Cassowary stepping out of the brush...

They're endangered thanks to a surprising culprit: pigs. There are roughly 24 million feral pigs in the Australian wilderness. About 60,000 of them reside in the Daintree and are wreaking havoc. All along the trail we saw spots where pigs had destroyed large patches of plant growth. They're out-competing the Cassowary for food, which has driven the Cassowary population down to about 1,000 birds.

Given the precarious population the government does what it can to protect them. There are a few dozen signs along the only road in the area warning people to slow down for Cassowaries; these are accompanied by a varied array of speed bumps. They're serious about protecting the birds, and with good reason. Obviously, the extinction of the Cassowary would be tragic, but because of its unique place in the ecosystem and its role spreading seeds in its waste (the digestive process actually makes some species of trees "growable"; otherwise they'd just rot on the forest floor), it's estimated that the loss of the Cassowary would lead to the loss of 30 species of plants. That's quite a domino effect for one animal.

Someone's modification to one of the many signs warning drivers about cassowaries.

The forest was a world that operated on a chemical level, remaining invisible to the untrained human eye. As we walked around Neil pointed out some of the actors that participate in this complex ecosystem on a daily basis.

One type of plant utilized sacrificial leaves. A single soft, pink-hued leaf would stand out amongst the green. Any insects looking for a snack would be drawn to this attractive leaf before attacking the green leaves. But once the pink leaf was attacked, a chemical signal would be sent to other plants to temporarily change their chemical makeup in their leaves, making them unpalatable. Even crazier, the plants in one area would rotate who displayed the sacrificial leaf, so one plant wouldn't take the brunt of the insect feeding frenzy.

Sacrificial leaf.

Neil also showed us a small mushroom the size of a nail head that glowed at night to mimic the female firefly. This mimicry attracted the male firefly, which would pick up spores when it landed and spread them around when it took off. The way plant life had evolved to exploit insect and animal life was impressive. One tree actually co-opted ants, beetles, a species of bird, and possums to keep away would-be pests and repair damage to its bark. Another tree emitted hydrogen cyanide, a poisonous gas, when attacked.

One tree species, called a Cycad, existed in the days before flying insects and -- since if it ain't broke, don't fix it -- still used flightless insects for pollination. The male cycad has a dome at the top of the trunk that is home to a number of insects. When it comes time to pollinate a female, it will raise the temperature in its dome by about 17 degree Celsius (that's over 60 degrees Fahrenheit). To escape the heat, all the insects will evacuate the male tree and hustle across the forest floor to the female tree to take up residence, taking bits of male pollen with them. When the female tree has been pollinated, it will raise the temperature in its dome, sending the insects back to the male tree.

 

Neil pointed out an innocuous looking plant, which has various named, but is generally called the Stinger or Stinging Tree. This is Australia's typically more venomous version of plants found in the rest of the world, like Poison Ivy. Touch its leaves and silica-tipped hairs will deliver a nasty neurotoxin. The excruciating pain the toxin causes can last for months and often requires hospitalization. An Australian Geographic article covered some of the consequences of contact: horses going mad and jumping off cliffs in agony, a military officer who shot himself after using the leaves as toilet paper, and pain returning years after exposure simply from taking a cold shower. The British were allegedly investigating its potential use for chemical warfare back in the 60s. Given the wide berth most animals give this plant, other species of plant have evolved to resemble the Stinger as a defensive ploy.

This plant gave off no smell or other hint of its danger, but Neil commented that if you brought an Aboriginal elder near a Stinger he likely would know he was close to one even if he couldn't see it. This comment came up because I was joking about a particular seed we passed. The seed looked like a cobalt blue egg and was a favorite snack of the Cassowary. Neil mentioned that aborigines could eat it after some significant processing and I quipped that the first person to eat it probably died, so the second person prepared it a different way and he died, so a third person tried it a new way, and on and on until someone figured out a recipe that wouldn't kill you. Very persistent people, I said.

The aforementioned blue seed.

The more likely situation, however, was that the aborigines were so in tune with the environment that they would have known just how to prepare it to neutralize any toxicity, just as animals somehow know which berries are safe to eat. Neil talked about how, after 26 years living in the Daintree, he was much more aware, unconsciously so, of his surroundings. (He amazed us on numerous occasions by pointing out insects on trees that were so well camouflaged you had to look hard to see them even when he pointed right at them. Imagine what he might know if he'd spent the first half of his life in the forest, coupled with knowledge gained and passed down through millennia.)

Much of this aboriginal "sixth sense" would have been thanks to the Jacobson's organ, found at the base of the nasal cavity, he said. The organ detects pheromones, which are the chemical messengers of the forest. While studies on whether adult humans have a functional Jacobson's organ are inconclusive, Neil surmised that the Jacobson's organ in someone who'd spent his life in the forest would be much more developed than a city boy's, and that most of the studies have probably been conducted on people who did not spend their lives living in the wild, so to speak. It was an interesting idea, and served to remind us how detached from nature our lifestyles have become.

To be continued...