Edwin Giesbers / Wild boar (Sus scrofa) piglet suckling from mother's teat, the Netherlands, April

John Cancalosi / Common brushtail possum {Trichosurus vulpecula} young suckling on teat in mother's pouch, Australia, captive

Rob Tilley / Japanese Macaque / Snow monkey (Macaca fuscata) at teat of mother, Jigokudani, Nagano, Japan

Jane Burton / Domestic Cat {Felis catus} 1-day blue kitten with medicine dropper and teat to supplement feed.