#parachela

Acutuncus antarcticus is the most abundant species of tardigrade in Antarctica, and one of the few animals native to Antarctica year round. They live on cyanobacteria and green algae and can live in their normal, active state for up to 161 days, though on average only live for 69. However, when the water that they need to survive in freezes over, A. antarcticus will enter a state of cryptobiosis, decreasing activity to a nearly undetectable level, ceasing to age until they are rehydrated. One outstanding case in 2015 demonstrated a frozen moss sample from 1983 that contained A. antarcticus tardigrades. From this sample, 2 adult tardigrades and 1 egg survived, despite being placed in -20 degrees Celsius for 30.5 years. This is the longest record of survival for tardigrades.

The entire genome of the tardigrade Hypsibius exemplaris has been sequenced. Hypsibius exemplaris has a compact genome and a generation time of about two weeks. It can be cultured indefinitely and cryopreserved.

Macrobiotus hufelandi, identified by German researcher Carl August Sigismund Schultze in 1834, is recognized as the first taxonomically named tardigrade species.

Macrobiotus shonaicus engage in a mating ritual which involves the male touching the female’s cloaca with his mouth several times until the female tardigrade stops moving. Both male and female then immediately molt before reproducing, developing mature oocytes to do so. Many other tardigrade species can reproduce parthenogenetically, but this species does not appear to be able to.