Threatened arthropods and described. The total number of living arthropod species is probably in the tens of millions. One conservative estimate puts the number of arthropod species in tropical forests alone at six to nine million species. As a consequence of all of the above, most published estimates of the total number of endangered insects and arachnids are probably low by at least an order of magnitude. Conservatively at least eighty percent of all living animal species are arthropods. Since arthropods constitute the majority of the faunal biomass on Earth, their role is vital to the survival of large numbers of insectivores
Stinger receiving the venom. Spiders only bite, although some tarantulas have urticating hairs. Certain caterpillars also have urticating hairs. Organs that perform similar functions in non-arthropods are often referred to as "stings". These organs include the modified dermal denticle of the stingray, the venomous spurs on the hind legs of the male platypus, and the cnidocyte tentacles of the jellyfish. The term "sting" was historically often used for the fang of a snake, although this usage is uncommon today. Snakes are said, correctly, to bite, not sting. Stinger A stinger, or sting, is a sharp organ found in various animals (typically