I was lucky enough to celebrate Christmas and New Years in Cape Town, South Africa. While I was there I heard terrifying accounts of groups of Orca (Orca orca), or killer whales, invading the bay and wreaking havoc on populations of dolphins that inhabit the bay. This is a seasonal event, and watchers have seen thousands of dolphins being chased right across the bay by groups of killer whales working together.
The really striking thing about this is that killer whales aren’t supposed to eat dolphins. Dolphins and killer whales are quite closely related. IN FACT, killer whales aren’t really whales at all. They are giant dolphins! So it’s almost like cannibalism to think that the Orca have begun to eat their little cousins. In fact, marine biologists who are studying the event say that the first time this was recorded happening was in 2009.
Strange and terrifying apex predators, what really makes Orcas so deadly apart from their speed, size, and terrific sharp teeth; is that they hunt together in packs. Poor dolphins!
Even stranger to hear, marine biologists are reporting that great white sharks (Charcharodon, carchiaris) which have haunted swimmers on this beautiful coast for years; are leaving the bay. What could be dissuading them, there are still plenty of seals and penguins to eat? The answer might be also killer whale attacks. Great white shark carcasses have been found floating in the bay with the liver and pectoral fins ripped off. It is believed that Orcas gang up on Great whites, rip off their pectoral fins so that they can’t defend themselves properly, and then eat their liver while they are still alive. This is enough even to give the mighty Great white shark nightmares. Is this also a new behaviour? Or is it simply becoming more common?
So what is causing these radical changes in behaviour amongst Orcas? Are these really new behaviours, or are we only now becoming aware of them? There are no well documented cased of wild killer whales attacking humans. They have decided either that they like us, or that we don’t look very tasty. What if they change their minds?
This week the seniors are tackling their Internal assessments for IB Biology. A unique and individual experiment has been created by each student, designed to follow a line of enquiry.
Unavoidably, set-backs plague the early stages of an investigation. It is the successful navigation of such challenges which often brings the most exciting moments in an IA investigation. In these moments of small triumph, students live the wonder of real science; where every new discovery is prefaced by a period of struggle and uncertainty. I would like to congratulate my current seniors on their hard work so far!
Some sample photos from this weeks investigations are included below.
May. A large group of Lincoln School teachers led by Iris Prada travelled to Veragua Research station in the province of Limon, Costa Rica.
The objective, was to explore the possibilities for creating new educational experiences for high school students.
The rich biodiversity, the park infrastructure, and the presence of highly skilled and dedicated researchers make this a real possibility that in the new future, the school will be working to provide some of these experiences for our students.
Biology field trip anyone??
Image credit Gerardo Abadia aka Mr Science
I recently visited the magical region of Monteverde, in Guanacaste province. There is probably no better place to enjoy the grandeur and dignity of plant evolution. From the tiny and featureless liverwort, which is so primitive it seems to be present only as a green smudge with no discernible features; up to the mighty angiosperms which dominate the canopy layer.
I took a nature hike through the salvanatura park, where 5 giant suspension bridges allow the visitor to inspect the canopy layer at the 100ft level. A dazzling array of bromeliads and orchids are on display, these little plants don’t do any work at all to reach such great heights, they merely catch a ride on a giant angiosperm. This method of growing on top of other plants, earns them the label of ‘epiphytes’.
Down on the forest floor I find myself sniffing around for bryophytes, another kind of nonvascular plant (non vascular means they don’t have any vessels for carrying around water or nutrients in their bodies; if you could imagine a person with no arteries or veins that’s like a bryophyte). Another name for bryophytes is mosses, or musgo in spanish. Ferns look beautiful, and in monteverde they grow as big as small trees; called fern trees. It is interesting to note that they are ‘non-woody’ and actually are much softer than ‘real trees’.
Climbing back up to the dizzying heights of the tree-tops again, we can see that apart from the cheeky ‘epiphytes’ the world seems to be ruled by giant angiosperms that reproduce using flowers and fruits. There is even an emerald toucan gobbling up some of them, and we stop to watch.
One group of plants that seems to be missing here is coniferophytes. These trees have needle-like leaves and pine cones, and their wood is aromatic and amongst the most beautiful in the known world. Christmas trees are coniferophytes. There doesn’t seem to be any of this group here, at least not in this part of the park. I wonder if they do a christmas bryophyte with a fairy on top in December? At least it wouldn’t take up much room!
I just climbed Volcan de Tajamulco, in Guatemala. That is the highest point in Central America, at 4,280m (14,041 feet). I stood alone at dawn at the summit, and spent one of the most blissful and inspiring mornings of my life.
Why is it that high altitude brings forth such powerful emotions. In the book Zorba the Greek, the author Nikolas Kazantzakis wrote of the sensation of climbing Mount Nikos “anyone would think that the soul too was an animal, with lungs and nostrils, and also craved oxygen”
Scientists know that high altitudes mean lower partial pressures of oxygen. This can actually cause the dreaded ‘attitude sickness’, because of a lack of oxygen supply to parts of the body, particularly the brain. This is dangerous, and can actually cause death in some cases.
Scientists and mountaineers alike have long been amazed at the hardiness, health and energy of people who live at high altitudes, such as the peoples of the Himalayas in Nepal. Samples of their blood have been found to contain extremely high levels of haemoglobin, the vital protein that transports oxygen around the body. Despite the dangers, could it be that there are other hidden undiscovered health benefits to moderate exposure to high altitudes?
I am extremely curious to know more. In the meantime, I will continue to enjoy the view!
The sun is rising – 5:00am Friday 27th November. In the creeping light, I am racing up a rocky pinnacle at just a little over 3,800m. The going is tough. My heart is pounding hard in my chest, and my lungs are working as hard as they can. I am running, scrabbling for balance with both hands on the bare rocks. To the left and right the rocks slide away into perilous falls. I can see the glimmer of a lake down to my left. I am about to summit Chirripo, the highest mountain in Costa Rica. I turn to see my climbing partner gaining on me… I whoop in exilharation, and then immediately regret it – I needed that oxygen!
With a last twist of the trail that sets my quadriceps muscles on fire, I see the flag of Costa Rica ahead of me fluttering in the first morning breeze, and I know that I have made it. Jubilation takes over, and I hug the suprised stranger who is the only man to beat me to the summit that day. We made it! The view is breathtaking, layers of clouds below us glowing in a ring of orange creeping light. I am freezing, even in my thermal base layer, fleece, mountain top, goretex jacket, and Andean wool hat and gloves. It can’t be much above freezing point. What a climb. What a dawn. What an amazing place to be.
And then again, what an amazing study of the effects of altitude on vegetation. Climbing mountains gives a biologist an amazing opportunity to observe something called ‘zonation’ in action. That is, when vegetation (and associated animal species) occur in discrete zones, delineated by geographical boundaries. In this case, the zones are defined by altitude.
We had started that day at the punishing hour of 3am from basecamp. At 3400m, this is already above the ‘tree-line’. Here only hardy bushes and xerophytic plants (adapted to desert-like conditions), will grow. Standing there on the top of CR, there is nothing alive except us. Well… probably some microorganisms grow, bacteria and algae. But mostly just rocks.
During the previous day, we had hiked 6 and a half hours from the village of San Gerardo de RIvas, witnessing truly remarkable changes in vegetation. Moist lowland forest had suddenly become gorgeous cloud forest, heavily clad with old man’s beard and orchids, which troops of white faced cappucin monkeys were literally ripping to pieces in their search for tasty insects. It was literally raining precious orchids, like a free-for-all herbarium.
Strange clusters of indigenous bamboo came and went, and when we crossed the treeline the change into scrub land was equally dramatic. Suddenly beautiful flowers appeared on both sides, and small cheeping birds fluttered on between the sparse foliage. A green spiny lizard followed us, one of Costa Rica’s highest living reptiles.
Okay, so why does this happen. Well, we know that at higher altitudes, a number of abiotic factors change. Air begins to thin, that means less CO2 for plants to draw on for photosynthesis. This also affects evaporation rates for water, which becomes faster. The effect of winds can be more strongly felt, as there is nothing to slow them down up there. There is also less shade. Basically it becomes more exposed, creating a harsh environment where water is scarce for plants. Presumably, the combination of these factors places a limit on how high certain species can flourish. This allows plants to grow which would otherwise be out-competed by the lower-altitude loving plants. At a certain altitude, around 3,600m, it’s too high for anything. When my two climbing buddies and I tried to do a little ‘independent exploration’, we soon found that this meant there is very little to hold on to. Climbing on bare rock on high altitude is a scerene but also intense experience. You know you are climbing higher than life itself dares to go. That makes it a little more scary, a but also a little more special.
So if you dare to climb this amazing mountain, watch out for the zonation!
photo credit www.govisitcostarica.com
Saturday morning, 8:30am. I am 25m down in the Pacific Ocean of the coast of the Guanacaste region of Costa Rica, next to a wave-rocked promontory they call ‘Isla de Murcielogos’, or ‘bats island’. The diving guide, an seasoned veteran known as Javier, raises his hand and signals to me by placing the palm of his hand straight up on the top of his head. His meaning is unmistakeable – shark.
Around the corner swims a beefy bull shark, his grey flanks rippling with muscle and his bunched mouth bursting with razor sharp teeth. He doesn’t seem to be much interested in us, however, he seems to be taking a stroll around the island. The thrill for us is a powerful one, and although we can’t talk to each other underwater, you can see feel the excitement in the quickening of our fins and in the widening of our eyes.
Diving with sharks on their own terms can be a powerful experience, and you can feel the majesty of their powerful domination over the saltwater aquatic ecosystems of this earth while reminding yourself that as long as you are not their natural prey you should be in little danger.
However there is another kind of diving with sharks that I object to. This is the kind where a thrill seeking tourist gets in a cage, and then all kinds of bloody lumps of meat are hung outside to attract the big predator sharks such as the great whites Carcharodon carcharias. Tourists then enjoy the sight of the sharks feeding next to them, beating against the sides of the cage even in a frenzy of bloodlust.
photo credit (www.travelsouthafrica.net)
I make my point later as we dine on a high terrace looking out of the bay at playa el coco. A large raccoon approaches the table and attempts to convince us to give it food. Obviously he has learned to associate humans with a source of food, and although he is still afraid he stands on his hindlegs and attempts to bully us into surrendering our lunch. I manage to drive the ardent mammal off, but there is a flash of teeth and it crosses my mind that I could get bitten. Time and time again the lesson has been drummed into me that we don’t teach a wild animal to associate humans with food. Even the smallest animal becomes dangerous. So if this is the case, why oh why, are we doing it with some of the most ferocious predators on the planet?
Things go wrong with a raccoon’s perception of humans, the worst we might have to suffer is teeth marks and a rabies shot. Teach a shark to associate humans with food, and you can have fatalities.
Western Australia banned cage-shark diving for this reason in 2012. The debate was heated, as cage-shark diving is a major earner in the tourist industry. South Africa, and Southern Australia are two places where you can still do cage-shark diving. Why is it not banned world-wide? Well, no one has actually proved that cage-shark diving causes sharks to attack people. This is curious, and fascinating. It does occur to the educated mind that it might … perhaps we are lacking the right team of scientists for the job.
We continue on our watery exploration of the seafloor underneath ‘Bats Island’, seeing many wonderful things including the tiny but spectacular harlequin shrimp. The sharks have been the stars though. So if you want an amazing experience, I do recommend going down into those waters, the last wild frontier on Earth, and seek a glimpse of one of the most impressive and efficient predators ever to swim in our seas. But leave the cage behind, go on – be a real diver. Oh yes, and remember – don’t feed them!
I lead an annual trip to Monteverde National Forest Reserve, near Santa Elena in Costa Rica. The last time I was there, it was in June with a group of IB Environmental Systems students from the Academia Britanica Cuscatleca in El Salvador. As we were settling into our lodgings, a visitor arrived.
Boldly sniffing around the doors to our cabins, was a male Coati or Pizote. With characteristically raised tail, stripey upturned face and strong nimble fingers, the Coati looks like a Rainforest version of a raccoon. Unlike most raccoons, the Coati often shows no fear of human beings, and this one swaggered up to my group of students and casually sniffed us for signs of food. None is totally sure why they stick their tails straight up, perhaps it is to let other Coati’s know where they are. But for a lone Coati such as this, this idea fails to explain it and it seems to me that it is trying to show us who’s the boss.
-Awww…que linda, went up the cry as everyone crowded around to see. I was cautious and warned my class not to get too close. And with good reason. The Costa Rican coati (or white-nosed Coati) Nasua narica has a formidable fighting reputation, with both sharp claws and razor-sharp teeth including canines. They are part of the same group as raccoons in the family Procyonidae, but tend to be more aggressive and fiercer hunters. If they are fed human food, this can cause them to associate humans with lunch and this is a dangerous idea. A coati could easily bite off a human finger. I ask the students to hold their hands up in the air away from the animal, and also to show clearly that they are carrying more food. We take some photos, and allow the animal to pass.
Unfortunately one trio of hapless girls have left their door open, and the male saunters in to inspect the premises. It is safer to open the door and wait for him to come out, which he does eventually after leaving a large dark dropping on the bathroom floor.
Scientists have reported that the Coati are sworn enemies of the highly dominant Cappucin monkeys, having a similar niche in the ecosystem as varied and efficient predators. On an animal survey hike later in the early evening, we witness firm evidence of this theory. A group of 10 coatis ascend into the trees and begin attacking a troop of Cappucin monkeys. An unfortunate mother monkey is separated from her family, and two Coati attack her from both sides. They rip the tiny infant from off of her back where it was clinging in desperation, and in front of my horrified class they murder it in cold blood and take it away in pieces. Our guide tells us that later the Cappucin monkeys may take their revenge.
In the meantime, my students are no longer likely to cry ‘aww…que linda’ next time they see a male Coati inspecting the cabins. However, like some of their human counterparts, they do have a certain roguish charm and I am always delighted to see one – Although when I do; I show them the same respect that I would if I had met Al Capone on a stroll in the rain-forest.
(photo of author with Pizote in Tamatin, Costa Rica)