19 October 2009

What does it mean when a snail's tentacles are vertical?

VerticalTentacles

This is a juvenile snail, either a Mesodon thyroidus or a Neohelix albolabris. I brougt it home in the beginning of July and have been waiting since then for it to form its adult lip so that I can put a definite name on it, but its refusing to grow.

And why is it holding its tentacles vertically?

11 comments:

owheelj said...

It's looking up?

Anonymous said...

Wow Aydin, what a great picture, and what a striking design it makes; it would make a fine logo! I have never ever seen a snail or slug hold its ommatophores perfectly straight up like that, in fact I didn't think they could even do that; this one has great muscle control! I know they don't have great vision, but am tempted to say that the snail is looking straight up, but actually in this position the eyespots are facing backwards slightly, so it is tempting to say that it is perhaps trying to look somewhat behind it and over the shell, towards the main light source, a window or overhead light? I know they don't see well, but they do seem to look in one direction sometimes. Take a look at this image:

http://en.wikipedia.org/wiki/File:Tigerschnegel_Einablage.jpg

Where you will see that it seems as if the Limax maximus is looking upwards, I think because the board under which it was nesting was suddenly removed and the light was a surprise to the creature. Nonetheless, you can see that the tentacles are curved upward, as is usually the case, not straight up to attention like your cute little juvenile here.

Best,

Susan J. Hewitt

AYDIN ÖRSTAN said...

I don't think it was looking at anything. As you note, Susan, terrestrial gastropods can't really see. I have done some simple tests with several species of snails & slugs & determined that their tentacles don't react (i.e., withdraw) unless an object is brought very very close, within ~1 mm, of the tip of the tentacle. Therefore, I believe the vertical holding of the tentacles in the picture signify something other than a visual response.

Megan said...

Your juvenile reminds me of Gary the Snail. : ) http://spongebob.wikia.com/wiki/Gary_the_Snail

Does it always hold its tentacles vertically? I once saw a snail whose tentacles were essentially fused together, which I guessed to be a strange congenital defect. Maybe this guy has some unusual musculature.

John said...

I see Megan got to it before me, but I was thinking that it looked like a cartoon snail.

AYDIN ÖRSTAN said...

You mean Spongebob's snail Gary? Meow...

No, my snail--maybe I should name him/her--can move its tentacles around.

Anonymous said...

Yeah, it's true that snails and slugs can't look "at" something like mammals can, because the eye spots are just simple light sensors, not real eyes, no lens and so on. But I assume they can perceive the difference between a really dark area and a really bright light. Do they move away from a bright light source preferentially? Have you tried that experiment? I imagine LED light is good for brightness without much heat.

Anyway, does this little creature hold its tentacles like that almost all the time? Or only sometimes? It's really comical, I have never seen a snail do that.

Susan

Kazimir Majorinc said...

Very pretty snail.

Anonymous said...

maybe it's just happy to see you?

Coyote said...

I've read that snail eyes do indeed have lenses, which means they can focus their vision to some extent.

I don't think they can see very well, but I suspect they can see better than we think they can.

Cindy said...

This is what I imagine was happening just off-camera.