Chironomus
Chironomus is a genus of nonbiting midges in the subfamily Chironominae of the bloodworm family, Chironomidae, containing several cryptic species that can only be distinguished by experts based on the characteristics of their giant chromosomes. The larvae of several species inhabit the profundal zone where they can reach relatively high densities. They use a combination of hemoglobin-like proteins and undulatory movements in their burrows to obtain oxygen in poorly oxygenated habitats.