This stick insect can propel chemical compounds called terpenes from glands on its metathorax, on its back near the third pair of legs. The chemical produces an intense burning sensation when it encounters a predator's eyes or mouth.
The American turkey vulture utilizes a similar strategy. If a predator approaches a nest, adult birds vomit stomach contents in a projectile manner. Not only is this potion acidic, but it may contain bacteria and foul- smelling partially-digested carrion.
A small bird called the Eurasian roller loves to eat grasshoppers. When threatened, the grasshopper releases chemicals derived from the plants they eat in hopes of leaving a bad taste in the bird's mouth. That may work for some birds, but not the roller.
The tobacco hornworm caterpillar consumes the toxic tobacco plant. It then secretes the toxins, including nicotine, through its skin in order to scare away predators. Researchers call this "defensive halitosis," or bad breath.
The Fulmar petrel, a type of seabird, extracts an orange oily substance from its food. When threatened, it can spit the oil up to six feet. This substance mats feathers and eats away at their waterproofing oils.
There are twelve species of spitting cobras. Unlike other snakes that use needle-like fangs to inject their venom, spitting cobras use their fangs to spray it. The snakes do this by squeezing the muscles around the venom glands.
Camels spitting on someone they don't like is common in comedy. It is also a real defense they utilize when another animal gets too close. What the camel spits is mostly vomit, which includes digestive acids from the stomach.
Whip scorpions are arachnids. They have claws like scorpions, but they lack a stinging tail or venomous fangs. Instead, spray an acid that smells like vinegar - but that is 20 times stronger than vinegar from two "turrets" on the abdomen.