Transcript:

“Well, it could have a vitamin that they need; it could also just be that there are so few fruits in the forest at this time of year.”

Welcome to Pulse of the Planet’s Science Diaries - a glimpse of the world of science from the inside. We join Earthwatch scientist Summer Arrigo-Nelson in Madagascar. She’s been observing the eating habits of tree-dwelling primates known as Propithecus Lemurs.

“Because it's the winter here in Madagascar, there aren't a lot of fruits being produced by the trees in the forest. We have a couple of species that are producing, and so the lemurs are returning over and over again to those trees that still have fruit in them. One of them is called tuvulu, and for Propithecus tuvulu's a really interesting fruit. Normally, Propithecus is what we call a seed-predator, which means when they eat a fruit they also eat the seeds, and they crush the seeds or they destroy the seeds. Now for the Propithecus that's really great because they're able to then digest and incorporate all of the fats from the seeds into their body; however for the tree it's a bad thing because those seeds, they're dead, there's no way that they'll produce baby trees in the future. But tuvulu actually has evolved a very interesting strategy. The tuvulu seed is so hard that not even Propithecus can bite into it. So watch the Propithecus up there in the trees, and they take these tuvulu fruits, which are only about the size of maybe your thumbnail, and they hold them in their hands and then really carefully with their front teeth they scrape this very, very thin flesh, all the way off the seed before they drop the seed down. And and there's also not a lot of pulp there so they have to eat a lot of fruits in order to be able to take in any amount of nutrition.”

And the more fruits the lemurs eat, the more seeds they spread. Check out Summer Arrigo-Nelson’s blog on pulseplanet.com. Pulse of the Planet’s Science Diaries are made possible by the National Science Foundation.