Triops is a genus of small crustaceans in the order Notostraca (tadpole shrimp). Some species are considered living fossils, with a fossil record that reaches back to the late Carboniferous, 300 million years ago. One species, Triops longicaudatus, is commonly sold in kits as a pet.
Innate immunity is found in both animals with and without adaptive immunity. The molecular components of the innate immune system do not appear to be closely related to the molecules of the adaptive system.
Cells of the innate system respond to pathogens in a very general, generic way. Their response does not change, regardless of the type of pathogen involved. Another key feature of the innate immune response is that it has no memory, and it cannot trigger the development of memory. The innate response is, in evolutionary terms, a much older defense system than the adaptive response â plants, fungi, insects, and more primitive multicellular organisms have innate immune defense systems.