22 February 2009

How a slug breathes—Part 2

Here is another movie I just made by taking sets of sequential pictures and then combining them in Windows Movie Maker. This one shows the eastern U.S. native slug Megapallifera mutabilis.

video

Note the slug's pneumostome (the breathing hole) towards the back of its head. In the beginning of both sequences, the pneumostome was open and then it closed.

The slug didn't like the bright lights I had shining on it and so it kept turning away from the camera. Hand-holding the camera at high magnifications invariably introduces instability. I may have to get a table top tripod.

My 1st gastropod movie was here. Part 1 of this series was this post from April 2006.

3 comments:

Tim Pearce said...

Nice job documenting the opening and closing of the pneumostome. But is that breathing? I am curious whether the slug expels air and inspires, or whether it simply opens the pneumostome and air difuses in and out. Can you put colored gas beside the pneumostome to determine whether a current in or out exists, or whether it is simple diffusion? Would a slug be able to blow out a birthday candle?

Megan said...

That's a nice, clear video - the pneumostome is usually rather small and hard to see.

You have an interesting point, Tim. Does it breathe like land vertebrates (meaning it would need a diaphram??), or does it take in air passively like a leaf (with stomata)? And does it mean anything that Limax maximus, a relatively active and speedy slug, apparently opens its pneumostome much wider than the Megapallifera?

Robert V. Sobczak said...

Well done: for as many snails as we have down here in south Florida, I've never seen a slug. Maybe I'm just looking in the wrong places.