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Mar 07

Organism of the week #9 – Not even what it doesn’t seem to be

See Roridula‘s glistening leaves. See the fly suffocating in her sticky embrace. Quake at her insecticidal prowess.

Roridula gorgonias [CC-BY-SA-3.0 Steve Cook]

Roridula gorgonias at Kew Gardens

Or not. Things are not quite what they seem with Roridula. For sure, she can catch flies, but her carnivory is impotent. She cannot make the enzymes she needs to break down her prey, so they remain stuck to her leaves, and do not give up their fertilising innards to her.

Or not. Things are doubly not quite what they seem with Roridula. We cannot take her out of her natural environment, and still expect her to behave precisely as she does in the wild.

In the wild, Roridula is not alone. She has an army of helpers:

Pameridea roridulae [CC-BY-SA-3.0 Denis Barthel]

Pameridea roridulae, an assassin bug [CC-BY-SA-3.0 Denis Barthel]

 Roridula is a home to assassin bugs and spiders. She cannot digest the flies she catches, but the assassin bugs and spiders make short work of them. And they turn the flies into manure, and this is what Roridula eats. She has outsourced her digestion to her helpers, and they benefit from the protection of her glue.

Or not. Things are triply not quite what they seem with Roridula. Although the assassin bugs have the decency to (ahem) fertilise on her leaves, the spiders don’t. Worse, they even eat the assassin bugs, adding insult to injury.

The spiders are cheats, free-loading on the outsourcing arrangement between the plant and the bugs.

And this is why the word “ecology” shares the same Greek root as “economics”.

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