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.
Invertebrate animals, which lack adaptive immune systems, have developed other systems of biological host defense, so called innate immunity, that respond to common antigens on the cell surfaces of potential pathogens.