Black Widow Spider
Black Widows are very poisonous spiders in the genus latrodectus and they are very well know for the hourglass shaped red mark on their otherwise black bodies. Even though they are very poisonous, their venom is very rarely fatal to healthy humans.
Black Widows "breath" through book lungs, like almost all arachnids. Book lungs are passages on the underside of the abdomen that draw air over membranes that allow for gas exchange. Hemolymph (Spider blood) then picks up the gasses and transport them throughout the body through veins and arteries where they are absorbed by the organs and muscles. The hemolymph is circulated by a thin tube on the top of the inside of the abdomen that contracts to pump the fluid through (it's a form of a heart).
Black Widows "breath" through book lungs, like almost all arachnids. Book lungs are passages on the underside of the abdomen that draw air over membranes that allow for gas exchange. Hemolymph (Spider blood) then picks up the gasses and transport them throughout the body through veins and arteries where they are absorbed by the organs and muscles. The hemolymph is circulated by a thin tube on the top of the inside of the abdomen that contracts to pump the fluid through (it's a form of a heart).