According to the Noah Webster's Dictionary, the etymology of the word "caterpillar," is uncertain. Something you can get from it though is: the word "pillar", meaning a cylinder shaped column, is in "caterpillar", and as you know, a caterpillar is a little tube shaped guy.
caterpillers
no
No
The group of caterpillars in invertebrates are any animal that is born with out and can operate without a vertebrae.
No
Birds
Leaves
leaves
Yes they do. And many of them.
yes
by eating plants
Not really.