Mushrooms have evolved to develop mechanisms, like toxins, that help keep them alive so they can reproduce, much like many other plants and animals. It’s a way of defending themselves from being eaten by animals, insects, and us.
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The mushrooms you see in the ground are actually the fruiting bodies of the fungus, which release spores into the air. One mushroom can release a billion spores, but if the mushrooms are eaten, the spores are lost.28 So, these poisons are a defence mechanism to protect the mushroom and help the spores disperse for more mushrooms to grow.
Whilst some mushroom poisons might only make the eater sick or feel unwell, some can be fatal.29 However, many animals and insects have evolved to avoid toxic mushrooms, with scientists seeing that some snails avoid poisonous mushrooms altogether.30
Some animals, like household pets, may be attracted to some mushroom species due to their scent. But they should be kept away from mushrooms in case they ingest one they shouldn’t. If you suspect your pet may have eaten a toxic mushroom, you should immediately take them to the vet.31