Arthropod Size

["Cliff Pickover ", 914 945-3630]

Could anyone review with me why an crustacean such as a lobster
could not survive if it were the size of an elephant.
Is it a physiological problem (surface area to volume ratio for
gills)?  Could such an organism walk on land or would it
collapse under its own weight?

If you respond, please send a note to cliff at watson.ibm.com as
I sometimes have difficulty reading the forum.

Thanks, Cliff