glands often associated with spines, teeth, or stings.
It may be primarily for paralyzing or killing prey or may be purely defensive. Some venoms also function as digestive fluids. Their effects can range from localized skin inflammation to almost immediate death; they include nervous-system excitation ( cramps , vomiting , convulsions) or depression ( paralysis , respiratory or cardiac depression or arrest), hemorrhage , red-blood-cell breakdown, circulatory collapse, and allergic reactions (including hives and inflammation). Many major groups of animals contain venomous species: snakes ( cobras , mambas , vipers , pit vipers ); fish ( stingrays , spiny sharks , certain catfish , puffers); lizards ( Gila monsters , beaded lizards); scorpions ; spiders ( black widow spiders, brown recluse spiders ); social insects ( bees , wasps , some ants ); and marine invertebrates ( sea anemones , fire corals , jellyfish , sea urchins ). See also {{link=antidote">antidote .