25. What two things about insect anatomy/structure explain the fact that insects do not get as large as we do?

[MarkJ0732]

Please help In need of biology help for a big project! Thanks!

[Sha7534]

One answer, I believe is their exoskeleton. If they got too big, it would be way too heavy for them to carry around.

[StephenF]

yeah, the exoskeleton is good, and another you could use would be their respiratory system. They have an open system (trachea), which basically means it's just a hole that air flows in through and diffuses through the membrane. This only works because they're small. The classic example is a grasshopper.

[Shauna2974]

1) Growth - Insects molt. They shed their exoskeleton and grow a larger one when when they grow. In the meantime they remain soft. If insects were as large as we are this would take a considerable amount of energy and would leave them as a heavy useless blob without anything to hold them up or allow them to move. They would be defenseless to predators between molts before the new exoskeleton grows and likely wouldn't survive and would die out. As insects in reality are small, gravity doesn't act so strongly on them and they can still support themselves and move. 2) Respiration - because of the way insects breath (through their external surface), the ratio of surface area to volume would decrease with increasing size and make it impossible for insects to breath if they were as big as we are. 3) Means of movement - Many insects fly, some can walk on the surface of water, others scurry quickly on the ground. These means of movement have contributed to their ability to escape predators and hence to their success and evolution. It is possible for insects to move in these ways due to weak gravitational forces on their small bodies. Ok, that was three things but maybe you can pick and choose.