So a few years ago, Hopkins pulled together a group of scientists interested in parasite conservation, and they started sharing what they knew. “That’s just not something that we’ve ever really prioritized,” says Skylar Hopkins, an ecologist at North Carolina State University. Yet we have barely begun to identify all the parasites, much less learn their lifestyles or monitor their populations. Of the 42 major branches on the tree of life, called phyla, 31 are mostly parasites. There are parasitic plants, parasitic birds, a bewildering array of parasitic worms and insects, and even a parasitic mammal-the vampire bat, which survives by drinking the blood of cows and other mammals. Parasitism has evolved as a way of life again and again, over billions of years, from the smallest and simplest microbes to the most complex vertebrates. If there’s an opportunity, someone’s going to evolve to fill it,” says Wood. It’s clever, when you think about it, and it’s exactly why parasitism is so common. Parasites opt out of the arms race between predator and prey entirely, choosing an easier path. Parasites proliferate because every living thing is a smorgasbord of nutrients and energy, and being a top predator isn’t the only way to get a bite of that bounty. More than a hundred different parasites have evolved to live in or on us, many of them now dependent on us for their species’ continued existence. Take humans: Despite our efforts to be unhospitable, we’re excellent hosts. Most species, it turns out, are parasitized by multiple others. Parasitic wasps alone probably outnumber any other group of animals, even beetles. Scientists think that’s only about 10 percent of all the parasites out there, leaving potentially millions more yet to be discovered. But the lions and zebras and fish are just homes for most of the life hidden in front of us.Īll told, 40 percent of known animals are parasites, and those are just the ones that have been described. When we humans look at a landscape, whether African savanna or Australian coral reef, we see the other host species, like ourselves. But modern conservation biology still considers those important parts of biodiversity.” A world of parasites “The public doesn’t give a damn about them.
“None of those things are cute and cuddly,” he says. There are plenty of nondescript plants and homely, squishy, or creepy-crawly invertebrates that are protected.
Of course, the modern conservation movement isn’t supposed to care about looks or charisma anyway, says Kevin Lafferty, an ecologist at the University of California, Santa Barbara. “But if you look at them under the microscope, they are just staggeringly beautiful.” “People think of parasites as gross and slimy and flaccid and wiggling, and that’s true some of the time,” says Wood. They’ve evolved ingenious means of survival, from the crustacean that becomes a fish’s tongue to the jewel wasp that paralyzes part of a cockroach’s brain and then leads it to a nest by its antenna, like a dog on a leash. If you get past the ick factor and get to know them, you may find parasites’ pluckiness eerily charming. Some experts say there’s an aesthetic argument for saving them, too. Not only is there much can we learn about parasites and ways to use them for our own needs (such as medicinal leeches, still employed in some surgeries), but we’re also starting to understand that they play crucial roles in ecosystems, keeping some populations in check while helping to feed others. Scientists warn of dire consequences if we disregard the rest.
But not all parasites cause noticeable harm to their hosts, and only a small percentage affect humans. This has made them the pariahs of the animal world. Of the more than 37,000 species flagged as critically endangered on the IUCN red list, only one louse and some freshwater mussels are parasites.īy definition, parasites live in or on a host and take something from that host. But right now it seems few people care-or even notice.
Nearly half of all known animals on Earth are parasites, Wood says, and according to one study, a tenth of them may already be doomed to extinction in the next 50 years due to climate change, loss of their hosts, and deliberate attempts at eradication. Wood has since become a leader in a new conservation movement that aims to save the world’s uncharismatic minifauna. I like to say that they got under my skin.” “I couldn’t believe that I’d been looking at snails for as long as I had and missing all the cool stuff happening inside them,” says Wood, now a parasite ecologist at University of Washington. Seen through the microscope, each one had two dark eyespots, which made them surprisingly cute and charming. The sausages were the larvae of the flatworm Cryptocotyle lingua, a common fish parasite.
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