Snails and poison hemlock

[coyote]

Mr Coyote and I have seen many kinds of snails when we go for walks in parks and nature preserves. Most of these places have poison hemlock growing in them, and we have seen snails on the hemlock plants.

Poison hemlock is very poisonous. It is what killed the anicent Greek philosopher Socrates. Its poisonous components are transdermal, meaning that they can be absorbed right through the skin, just by touch. (Such an exposure probably wouldn't kill a human being, but it will make you feel pretty sick for a while.)

So, if just by touching any part of the plant can transmit the poison, how could the snails we saw be on the plants without getting poisoned by them? One would think that their foot in contact with the stems would be absorbing the poison.

Could snails have a natural immunity to the poison? I rather doubt that, because the poisonous alkaloid, coniine, is a neurotoxin, which disrupts the workings of the central nervous system and is toxic to people and livestock.

Or is it possible the layer of slime is enough of an insulation between the foot and the plant, and that the slime does not absorb the poison?

Of course, another possibility is that the snails in fact do get poisoned by the plant. Perhaps the ones we saw were not sleeping on the stems, but were dead. (The snails were native California snails, but poison hemlock is not native to North America, although it has become widely naturalized.)

Can anyone solve the mystery of snails and poison hemlock?

[Rachel]

hmm, well snails are proven to have a good immunity to various piosons and irritants, e.g. stinging nettles, so it is possible thats the same. The snails mucus acts as a barrier against things it detects as being toxic. As you have probally seen if a snail gets dirt on the bottom of its foot as it moves its is left behind with blobs of its slime, it works the same way with toxic plants, they leave the toxins behind , although liquids and most chemicals will be absorbed as they are made up of smaller particals that will easily move and seperate.
does that help?

[coyote]

I suspected the mucus provided some degree of protection, but I didn't know how easily the hemlock's toxins could get absorbed through it.

[helikulo]

I have also read that snails can eat toxins that we can't - stinging nettles are a good example, as noted by thesnailsanctuary.

[coyote]

There is so much we don't know about snails. I wish I knew more about them. They are some fascinating creatures.

[whodoesntlovesnails]

but would we still love snails as much if we knew everything about them? then we might loose our fasination twords them

[Rachel]

there will never be anyone who knows all about one thing. The mysteries of life in all form are complex, and always changing and evolving.

[coyote]

No matter how much we learn, there will always be more to learn. That's why I like to keep studying things I've studied already, because there is always new knowledge.

[Val]

coyote said:

No matter how much we learn, there will always be more to learn. That's why I like to keep studying things I've studied already, because there is always new knowledge.

This is so true, we shall never know everything and this is a very interesting thread!!

Val

[whodoesntlovesnails]

but maybe that is why we are so interested in snails, because they are so mysterious...hense the name blue, white, yellow mystery snails.