Water rail
Water rails are omnivorous, although they mainly feed on animals. These include leeches, worms, gastropods, small crustaceans, spiders, and a wide range of both terrestrial and aquatic insects and their larvae. Small vertebrates such as amphibians, fish, birds and mammals may be killed or eaten as carrion. Vertebrates are impaled with a strike of the bill which breaks the prey's spinal cord. Plant food, which is consumed more in autumn and winter, includes the buds, flowers, shoots and seeds of water plants, berries and fruit. In south Asia, paddy (harvested rice kernels) may sometimes be eaten. The young rails are fed mainly on insects and spiders. Food obtained on land or from mud is normally washed in water before it is eaten. After rain, rails may probe soft ground for earthworms. This species will occasionally feed in the open even when not forced to do so by cold weather; Edmund Meade-Waldo described seven rails feeding in an open meadow. Despite its skulking nature, the water rail appears to thrive in captivity when fed on animal food such as raw meat or earthworms; one individual was taught to jump for worms suspended from a fishing rod.
Xerocole
Xerocoles get a substantial amount of hygroscopic water from their food. Many feed on moisture-filled plants: the aardvark obtains water from the wild cucumber and the camel eats succulents and bushes in the winter, getting enough water to go two months without drinking. The oryx eats "Acacia" leaves late at night, when water content is highest: in the hot, arid daytime the leaves are only 1% water; but in cooler, more humid night the leaves are 40% water. Some xerocoles are able to obtain water from halophytic (saltwater) plants, as they can metabolize high amounts of oxalic acid and produce very concentrated urine. The chisel-toothed kangaroo rat also mitigates the saltiness of the halophyte it eats (the shadscale) by using its broad, sharp lower incisors to scrape off the leaves' salty outerlayer to reach the less-salty center.