The clean-up crew is the name that has been used by many aquarists and vendors since the late 1980s to refer to various small invertebrates commonly sold for use in keeping the reef aquarium clear of pest algae. The three most popular have long been blue-legged hermit crabs, turbinaria snails, and emerald crabs though there are a variety of other clean-up crew animals available such as scarlet hermits, various snails, limpets, brittle stars, etc. Even peppermint shrimp that feed on pest Aiptasia anemones are often included. Sometimes it is used for the shallow sediment-dwelling animals that live in the deep sand bed of marine aquariums or reef aquariums.
Clean-up crew terminology has also been used for various arthropods, primarily a few established lines of isopods and springtails, used in terrarium clean up since the late 1990s. The two most popular have long been the Spanish orange Porcellio sp. (often falsely labeled P. scaber) and a moderately large and prolific entomobryid known as the "giant" springtail. These small workers help to keep various small animal enclosures (for dart frogs, salamanders, centipedes, whipspiders, etc.) clear of decomposing food particles that othwerwise can result in mold growth, mite infestations, or oxygen depletion from decomposition.