Insects are the only invertebrates to have developed active flight capability, and this has played an important role in their success.:186 Their muscles are able to contract multiple times for each single nerve impulse, allowing the wings to beat faster than would ordinarily be possible. Having their muscles attached to their exoskeletons is more efficient and allows more muscle connections; crustaceans also use the same method, though all spiders use hydraulic pressure to extend their legs, a system inherited from their pre-arthropod ancestors. Unlike insects, though, most aquatic crustaceans are biomineralized with calcium carbonate extracted from the water. COUNT 5
QSN1 Insects are also known as what kind of vertebra? ANS1 invertebrates QSN2 Insects have developed what kind of active capability? ANS2 flight QSN3 Active flight ability has played what kind of role for insects? ANS3 important QSN4 How many times are insects muscles able to contract? ANS4 multiple QSN5 Insects muscles are attached to their what? ANS5 exoskeletons