IronSmithFE t1_itom1vl wrote on October 25, 2022 at 4:12 AM

i was told a long time ago that there is a physical limit to the size of a creature with an exoskeleton because of weight constraints among others. i don't remember exactly what that constraint was but i believe it was something like the size of a football.

according to my source, the internal skeleton model allows for much larger construction. i don't know how this applies exactly but i imagine, if true, that larger creatures with exoskeletons might have needed thinner shells just to remain mobile.

Diligent-Jackfruit45 t1_itowg7w wrote on October 25, 2022 at 6:08 AM

IIRC its not so much the rigid structure that determines the size of an insect but the fact that they rely on diffusion to oxygenate their cells. Get too big and the oxygen requirements of the creature grow too large to overcome without specialized organs like lungs.

IronSmithFE t1_itp0rkn wrote on October 25, 2022 at 7:06 AM

now that you mention this, he had stated something to that effect as well. of course, supposing a creature had only an exoskeleton but also had lungs, it still seems like it would be limited on size because of rigidity and weight.

the expert, i think, was arguing against the bugs in starship troopers as impossible creatures.

Madeforbegging t1_itoqo9a wrote on October 25, 2022 at 5:00 AM

The fossil records contain ARTHROPOD fossils like centipedes almost 6 feet long.

IronSmithFE t1_itottx8 wrote on October 25, 2022 at 5:36 AM

a 6-foot-long centipede could curl up in an area smaller than a football depending the centipede's flexibility and short diameter. so, i don't think that disproves the assertion.