The pitcher plant (Sarracenia purpurea) in Ontario, Canada is a type of carnivorous flora well-known for chowing down on hundreds of different species of insects. Now plant has developed a taste for amphibians, baby salamanders.
According to a recent study published in the journal Ecology, scientists have found that about 1 in 5 pitcher plants in Ontario’s Algonquin Provincial Park have also made a habit of capturing, killing and digesting juvenile salamanders, too.
According to the study authors, this is the first research showing that carnivorous pitcher plants, also known as turtle socks, make vertebrates a regular part of their diets.
“This crazy discovery of previously unknown carnivory of a plant upon a vertebrate happened in a relatively well-studied area on relatively well-studied plants and animals,” study co-author Alex Smith, an associate biology professor at Ontario’s University of Guelph, told Live Science in an email.
“I hope and imagine that one day the general public’s interpretive pamphlet for the bog will say, ‘Stay on the boardwalk and watch your children — here be plants that eat vertebrates!”
The northern pitcher plant is one of roughly 600 carnivorous plant species around the world. Researchers found these plants are capable of dissolving a dead salamander in as few as 10 days.
With goblet-shaped leaves, pitcher plants collect rainwater to attract and trap various insects and invertebrates. Once caught in the pitcher, hapless bugs are slowly dissolved by a mixture of microorganisms in the water and digestive enzymes produced by the plant. The bug dies, and their carnivorous captor gets a free nutritional supplement.
Smith and his colleagues at the Universities of Guelph and Toronto first discovered salamanders — both living and dead — floating inside these pitchers during several sessions of field work at Algonquin Provincial Park in 2017 and 2018.
In four separate surveys, the researchers sampled the contents of several hundred pitcher plants in a small section of the park’s wetlands. They investigated in late summer, when young salamanders tend to metamorphose, leaving the comfort of their native lakes to venture onto dry land for the first time. The researchers found that roughly 20% of the surveyed plants contained at least one salamander, living or dead, and that numerous pitchers had captured more than one salamander at a time.
Once trapped in a pitcher, the salamanders survived from anywhere between three and 19 days before their watery jails became watery graves; some salamanders drowned, others starved and others still cooked to death in the hot, acidic pitcher water (pitcher fluid has a pH of less than 4, making it about as acidic as orange juice). Once dead, salamanders appeared to decompose in 10 days or less.
Overall, this high frequency of capture suggests that salamanders might be “a substantial nutrient source for pitcher plants,” the authors wrote. On the flip side, pitcher plants appear to represent a substantial existential threat for young salamanders, with as many as 5% of the bog’s juvenile salamander population falling prey to their leafy neighbours in a given year.
Why do so many young salamanders end up as plant food? It’s possible that the unseasoned amphibians treat the pitchers as a sort of watery refuge from perceived threats during their first excursions out of the lake and onto the land, the authors wrote — or, perhaps they’re simply drawn to the many species of insects that flock to pitcher plants for a few sips of sweet nectar.
In any case, the carnivorous plants appear to be far more carnivorous than previously thought. .