Termites are closely related to cockroaches based on a primitative termite species found in Australia. The fossil record suggests that termites have existed for approximately 200 million years. Isopterans are the oldest known social insect.
Isoptera consists of over 2600 species (mostly tropical). Termites are the oldest social insect group with complex societies dating back at least to the early Cretaceous (140 Mya). Only 12 species occur in Europe. Recent studies have shown that Isoptera are basically social cockroaches forming a monophyletic clade within the Blattodea, most likely the sister group of the Cryptocercidae (woodroaches) (Inward et al. 2007). Termites are the only hemimetabolous insects that exhibit true social behavior. They build large nests housing an entire colony. These colonies contain adult reproductives (one queen and one king) plus hundreds or thousands of immatures that serve as workers and soldiers. Termites are important decomposer animals in lowland tropical ecosystems. They mostly feed on dead plant material and are able to digest cellulose with the help of symbiotic gut symbionts.
About 2, 900 termites have been described worldwide. They undergo simple metamorphosis. They are eusocial insects and nymphs grow into one of the castes, where they will specialize in a job for the colony. A colony would consist of: a king, a queen, workers, and soldiers. The colony lives in nests, which are mostly built with saliva, mud, and soil. Nests are typically underground, but some can grow above the surface, with some of the tallest going thirty feet high. Termites have soft bodies that need to be kept moist and the nests provide the necessary protection and thermoregulation for the colony to survive. They frequently groom each other with their mouths. Termites feed on wood, leaf litter, or soil. They have bacteria in their gut, which aids with the digestion of cellulose. As detritivores, they play a huge role in nutrient cycling. They can be found in the fossil record as far back as the Late Triassic.
Termites are found in dark, damp areas whereby they are not exposed to air. They require a source of moisture to survive. In temperate regions, they are found in dead tree stumps, dead logs, and in the soil. They are also found in dry wood strucures where the termite nest has been established in the soil. Timber-based colonies may contain hundreds of individuals.
In tropical regions, termites are found where cellulose-rich food sources exist, in both living and dead vegetation. Some tropical termite species are known to raise giant mounds consisting of termite feces, soil, and fungi. These mounds may contain millions of individuals.
Isopterans get their nutrition from cellulose in wood. Digestion of wood occurs by bacteria and protozoans in the intestinal tract of many termites. Young termites acquire the microorganisms when workers feed them.
Some tropical termites use cultivated fungi to predigest food rather than microorganisms.