Kangas joined Nightly Business Report in 1979; in 2003, his Stocks in the News segment earned a Financial Writers and Editors Award from the Medill School of Journalism at Northwestern University. In 2005, he won a Suncoast Chapter Silver Circle Award.
What Is a Malpighian Tubule? Malpighian tubules are organs within insects that excrete solid waste. Larvae of certain species of beetles use Malpighian tubules to produce silk.
The primary excretory organs of insects are the Malpighian tubules and the rectum. Most insects have a variable number of Malpighian tubules (2  250), but the primitive collembolans (and aphids) lack them. There is no filtration and the primary urine is formed by secretion of solutes and water.. In metanephridia (functional definition) the blood is filtered under positive hydrostatic pressure. Colloid osmotic pressure in blood acts against the hydrostatic pressure, but the net filtration pressure will be in the direction from the blood to either the coelom or the duct directly.