In August 2018, Alexander Smith, a molecular ecology professor at the University of Guelph, was instructing a field course at the Wildlife Research Station in Ontario’s Algonquin Provincial Park. Smith was teaching the students about carnivorous plants found in Ontario’s bogs, specifically the pitcher plant—a glass-shaped flora that can be found all the way from Ontario to Newfoundland and as far south as the northern regions of Florida.
Smith pointed out several pitcher plants to his students. Inside one of the plants, however, was a dead juvenile spotted salamander. “Well, that’s a surprise,” Smith said. He’d never seen a vertebrate animal fall prey to a pitcher plant. He made a note to investigate the observation further.
A few nights later, Patrick Moldowan, a Ph.D. candidate in the University of Toronto’s department of ecology and evolutionary biology, arrived at the Wildlife Research Station to collect samples for his research on salamander and turtle ecology and conservation. Sitting across from one another at a picnic table during dinner, Moldowan and Smith started chatting about the salamander in the pitcher plant. The incident perked Moldowan’s interest, and the two men agreed to research it further.
The result is a comprehensive study published in the journal Ecology. The study revealed that Smith’s observation was not a one-off situation. Ontario’s pitcher plants do, in fact, prey on spotted salamanders. According to Moldowan, 20 per cent of the plants in their initial sampling contained salamanders. “We had over 35 individuals trapped among about 70 plants over the course of one season of sampling,” he says. “It’s unprecedented.”
Pitcher plants grow in bogs and other areas where there is nutrient-deficient soil. As a result, they typically derive their nutrients from insects, like ants and flies, and sometimes moths and small butterflies. The insects are drawn to the plant by a sweet nectar secreted around the plant’s opening. The study theorizes that the salamanders are, in turn, lured into the plant when they try to eat the insects. Due to the plant’s glass-like shape, its basin is filled with rainwater. Once the salamanders have fallen in, they are unable to crawl back out.
“What we’re seeing here is really a predator-prey relationship,” Moldowan says. “It’s not as in-your-face as a cheetah chasing down a gazelle along the Serengeti, but nevertheless there’s a sort of role reversal in which this plant, which is stationary, is managing to catch a mobile animal and turn it into its prey.”
Within the pitcher, the rainwater is slowly changed by the plant. Research shows that the plant releases digestive enzymes, like a stomach helping to break down food. “You can kind of think of the digestion and the decomposition as a two-stage process,” Moldowan says. “The first is sort of the physical breakdown, so that would be by small insects and bacteria and other microorganisms that live within this fluid in the plant. And then stage two is the chemical breakdown. And that would be through the enzymes.”
Moldowan adds that some organisms are unaffected by the plant’s digestive enzymes. He points to mosquitoes as an example, who actually breed in the pitcher plant’s fluid. Salamanders, on the other hand, are extremely vulnerable to the plant’s fluid.
The results of the study have only left Moldowan and Smith with more questions. The researchers still aren’t sure what effect digesting a salamander has on the plant. Moldowan theorizes that these salamanders act like a megadose of fertilizer. “It’s that T-bone steak instead of eating a little ant here and there,” he says. “These plants are getting a massive dose of really rich nutrient pulse when they manage to catch an animal like a salamander.”
As a result, Moldowan says the plant can likely devote more energy to growth and reproduction; things like seed output in the following year. But these are all hunches, ones that need to be investigated further. Moldowan, however, is looking forward to the opportunity. “To be honest, I’ve never been that interested in plants, but this plant has piqued my interest.”