Legs: true or false!

After the rainy weekend we are back to one day of sunshine, so I managed a short walk by the river where I met this caterpillar. I asked it to show me the difference between true and false caterpillar-legs. He climbed up a stem of a flower and for a moment I thought he wasn't going to answer, but then he paused in this L-shaped position, looked at me and, well, I think he actually smiled.
On the thorax (corresponding to the leg of the L shape my friend made) there are the six (three pairs of) true legs that correspond to (and will become) the six legs of the adult insect. They have got a kind of a claw at the end that is useful to keep the caterpillar anchored to whichever surface it finds itself on. On the abdomen (the stem of the L shape) there are then 3-5 (and sometimes more) pairs of false legs.These prolegs lack the five segments (coxa, trochanter, femur, tibia, tarsus) of the thoracic legs and they have limited musculature instead they have small circle of gripping hooks, called chrochets. The prolegs disappear when the larval body "melts down" in the cocoon and will not become part of the adult butterfly.
After this short demonstration, the caterpillar was off to look for food and to show me how the differential concerted movements of the prolegs and true legs created the “inching” motion that characterize many caterpillars.