#Interesting# In fact, the biggest difference between invertebrates and vertebrates is their nerve conduction speed. Except for the squid, all invertebrates will look very clumsy once they become huge.
Look at the real coconut crab is a living example of invertebrate giganticization (not very large, but much larger than ordinary arthropods and the like). How clumsy coconut crabs are, probably those ancient giant insects are similar.
There are many Carboniferous giant arthropods, but not as big as thought. Most of them are not more than 1 meter in size, and the nerve response is sufficient. But in the ocean, it's the other way around, and there are no sea scorpions after the large-scale expansion of jawed fish.
Later, first amphibians appeared, giant insects arthropods and so on were basically extinct, all of which developed towards miniaturization. Then came the Zygopoda and the Lizard, and for the next few hundred million years the land and sky became an arena for these two to compete with each other and rule in turn. After each mass extinction, there is a gap, either the synthesis seizes the opportunity to gain a dominant position, or the sauromorphs seize the opportunity to crush the syngonals. After each cataclysm, a new dynasty (dynastic change) was created, ruled by the Synthesis or Lizards, but no big bug ever seized the opportunity of the post-disaster gap to rule the land or sky again. Even in the sea, arthropods are generally low in their ecological niche.
The big insects of the gigantic insect era were the size of pigeons... The whole phylum of the hexapod does not take the route of giganticization, and the large ones in the arthropods are in the crustacean subphylum.
In addition, the ecological niche of large-scale arthropods after landing is not high, and the size is mostly limited to about one meter: the largest Hibbert horseshoe crab among the anchopods is a person who picks up debris or carcasses in muddy or puddles to eat, and its actions are clumsy and not many in number; The giant arthrothoracic worms in the polypods are not as exaggerated as in the documentary, and are likely to feed on plants or fungi; The giant veined dragonfly in the insect has a wingspan of less than one meter. Carboniferous insects or other arthropods are not large at all, just a few. Giant insects are essentially because vertebrates haven't landed long enough, so arthropods can still maintain their terrestrial niche.
It is worth saying that the muscle output is proportional to the cross-sectional area of the muscle, that is, proportional to the square of the size. Inertia is proportional to mass, that is, to the cube of dimensions. 1 square centimeter of muscle moves a 1 kg arm faster than a 4 square centimeter muscle makes an 8 kg arm move. As soon as the small grasshopper jumps three feet, the big grasshopper can only jump up with the help of wings.
Of course, more serious is the bone load. Not to mention Ant-Man, if the material remains unchanged, it is difficult for people to stand without enlargement to 3 meters.
And invertebrates have a nerve transmission speed of one meter per second, which is fast for insects of a few centimeters, and too slow for large vertebrates, such as a lion-sized praying mantis touching her tail, it takes two seconds to transmit to the brain, and the brain responds, and it takes two seconds to transmit to the muscles. It will be slagged by vertebrates in seconds. #自然 #
