Ticks With Noses in Their Legs

Ticks, remote spider relatives, smell with their front legs. When these legs are amputated the tick shows no reaction to odors. It cannot smell blood but will feed on any sort of liquid sucked through a warm, moist membrane like the skin. Presumably such a tick in nature recognizes an animal as a proper source of food by smell, while a combination of warmth and moisture from the skin gives a stimulus for feeding.