Ahhh, once again its summer, which brings back memories of my childhood summers. Summer means worms, which inevitably mean worms being captured and cut in half while all of the neighborhood kids ooh and ahh. I have a few questions about this phenomenon now that I am older and perhaps wiser. When you cut a worm in half, how does it survive? What is the life expectancy of a cut up worm versus a whole worm. Does it hurt the worm to be cut in half?(I’m pretty sure it does, I just want to feel more guilty). Does the worm realize that it has been cut in half and that other worm is, in reality, itself? What is the anatomy of an average worm that you would find in your garden? When it is cut in half, will it be missing a few important body parts? Are there any other animals or insects that are able to be cut in half and still survive(other than magic tricks where the woman is sawed in half)? Thanks.
IANAWE (Worm Expert, of course) but my understanding is that it all depends on where the worm is cut. In effect, what actually happens is that if the worm is injured it has the capacity to regenerate a tail. If it is critically injured the chances are that it will die (see here for more - pdf)
No, only a few ‘higher’ animals are able to grasp the concept of ‘self’. I don’t know if there’s any scientific evidence, but I’d be very surprised to see this exhibited by insects or similar.
As above really. Worms do have five hearts, so where the cut is will be relevant. It’s a misnomer to think that lots of worms are actually a subset of previous individuals though!
Some species of lizards are able to regenerate tails in a similar way. I’ll leave it to some other expert to explain the detail though…
J
Some *other * expert indeed. I mean, of course, an actual expert!
Starfish are well known for it. Here’s one regenerating from a single ray:
Worms are very simple animals. Each segment (I assume we’re talking about annelids) is mostly identical to the ones before and after it. As long as it doesn’t lose the unique organs in the front of the worm (ganglia [simple brain], hearts, mouth/pharynx, and crop), it can survive if it loses rear sections, as the remaining sections will continue to function.
Not if you cut them ‘lengthways’ 