How many species of insects are there as of 2017?

There are at least 900,000 species, but many more probably have yet to be discovered. Insects all have bodies consisting of a head, a thorax of three segments, usually three pairs of legs and often one or two pairs of wings. Their heads have compound eyes and long antennae that are sensitive to touch and smell.

the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.