Could insects ever grow to the size of some crustaceans such as lobsters for example?
There are two limitations on the size of insects: getting oxygen and nutrients to all of their tissues, and the weight of the exoskeleton. Insects have relatively primitive circulatory and respiratory systems compared to vertebrates. They have an inefficient, open circulatory system, in which blood pools in the body to bathe all of the cells rather than staying within blood vessels. Also, they exchange oxygen directly to most tissues via tracheae, a network of air vessels that run through their body the way blood vessels run through larger animals. For tiny animals, these systems are much more efficient than building a complex circulatory and respiratory system. However, a large animal could never achieve adequate nutrient, oxygen, and waste circulation with these systems. The other limitation on insects’ size is the weight of their exoskeleton. Larger animals need a thicker exoskeleton to support their weight and provide adequate attachment points for their muscles. As animals with ex
