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The Vegetarian Plant

Meet Utricularia. It’s a bladderwort, an aquatic carnivorous plant, and one of the fastest things on the planet. It can catch its prey in a millisecond, accelerating it up to 600g.

Once caught inside the prey suffocates and digestive enzymes break down the unfortunate creature for its nutrients. Anything small enough to be pulled in won’t know their mistake until it’s too late. But as lethal as the trap is, it did seem to have some flaws. The traps don’t just catch animals, they catch anything that gets sucked in, so often that’s algae and pollen too.

A team at the University of Vienna led by Marianne Koller-Peroutka and Wolfram Adlassnig closely examined Utricularia and found the plants were not very efficient killers. Studying over 2000 traps showed that only about 10% of the objects sucked in were animals. Animals are great if you want nutrients like nitrogen and phosphorus, but half of the catch was algae and a third pollen.

1500-Bladderwort_Trap(1)

What was more puzzling was that not all the algae entered with an animal. If a bladder is left for a long while, it will trigger anyway. No animal is needed; algae, pollen, and fungi will enter. Is this a sign that the plant is desperate for a meal, and hoping an animal is passing? Koller-Peroutka and Adlassnig found that the traps catching algae and pollen grew larger and had more biomass. Examining the bladders under a microscope showed that algae caught in the traps died and decayed. This was more evidence that it’s happy to eat other plants too. It seems that it’s not just animals that Utricularia is hunting.

Koller-Peroutka and Adlassnig say this is why Utricularia is able to live in places with comparatively few animals. Nitrogen from animals and other elements from plants mean it is happy with a balanced diet. It can grow more and bigger traps, and use these for catching animals or plants or both.

1500-Bladderwort_whole_plant

Fortunately even the big traps only catch tiny animals, so if someone has bought you one for Christmas you can leave it on the dinner table without losing your turkey and trimmings in a millisecond.

Photos courtesy of Alun Salt.

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