Tardigrades, also called “water bears” or “moss piglets” are a phylum of eight-legged segmented mirco-animals. They are usually 0.5mm long when fully grown.

Tardigrades are among the most resilient animals with individual species able to survive extreme conditions such as exposure to extreme temperatures, extreme pressures, air deprivation, radiation, dehydration, and starvation. They have survived exposure to outer space. In order to survive these extreme conditions, the Tardigrades go into a “tun” state, in which their body dries out and their metabolism drops to as little as 0.1 percent of its normal rate. When conditions return to normal. the tardigrade revives itself. Amazingly a tardigrade can stay in a tun state for decades!

Tardigrades are short and plump with four pairs of legs, each ending in claws and suction disks. They are prevalent in mosses and lichens and feed on plant cells, algae, and small invertebrates.

Tardigrades in a deep well slide at 200x courtesy of Win Aye.

Tardigrades crawling on a semi-wet moss leaf in a deep well slide at around 200x magnification. Video courtesy of Win Aye.

Tardigrades emerging from a tun on a glass slide at approximately 200x magnification. Video courtesy of Win Aye.