water scorpion: long-legged aquatic insect having the front legs fitted for seizing and holding prey and the abdomen extended by a long breathing tube
water bug: a true bug: large aquatic bug adapted to living in or on the surface of water
dalton's law: (chemistry and physics) law stating that the pressure exerted by a mixture of gases equals the sum of the partial pressures of the gases in the mixture; the pressure of a gas in a mixture equals the pressure it would exert if it occupied the same volume alone at the same temperature