My son, who is 12, has a few questions about spiders I have been unable to find the answers to. I would be very grateful if you could please help us, thank you.

He seems intent on really understanding exactly how spiders move. My best interpretations of his questions are:

How do spiders move their legs? We found some information about open circulatory systems and things but his question is more about what movement or pattern does a spider’s legs move in and how do they move...(he seems convinced that spiders and ants legs are on 'sidewards' and move 'sidewards' like the oars of a rowing boat...? and therefore he wants to understand if and how spiders legs can walk 'sidewards'... in order to move forward...)

Do spiders individual legs each have their own separate forward facing direction (like our own feet both face forward and in the same direction)? I.e. do a spider’s 8 legs all face the same direction, like our 2 legs do?

(And my personal favourite ) Do spiders have feet and if not, why not?

Thank you in advance for any clarification you could offer us.

See
http://en.wikipedia.org/wiki/Spider#Locomotion

http://blogs.cornell.edu/naturalistoutr … bpzbvb.pdf

Your son's questions are awesome!

The feet are indeed there, and called Tarsi. Often they have 1 - 3 claws, which can be saw like (serrated) for extra grip.

Many spiders the front (4) legs are directed so stretch forward, and the rear (4) legs streatch backwards, so in total mostly forwards backwards. But, in particular the middle legs can change angle, so help the spider rotate.
Some spiders have primarily sideways legs - laterigrade. Crab spiders in particular. Then indeed movement will often be sideways, but these often prefer just to sit and wait ... so not much movement at all!

Please tell your son i enjoyed his excellent questions!
s