Bryophytes are among the ‘preferred’ habitat for microscopic animals called tardigrades, otherwise known as waterbears or moss piglets. Although, tardigrades aren’t that fussy about habitat, being found in most habitats on earth. Over 1150 species are known worldwide, with about 90 in New Zealand.
What are moss piglets and why are they in space?
Tardigrades, or moss piglets are tiny segmented invertebrates with eight legs. They require a wet environment and feed on plant cells or other invertebrates, even other tardigrades. My kids re-introduced me to tardigrades, through the popular animated show Octonauts (Series 3 Episode 2), which accurately depicts the animals (although in real life they can’t talk). Recently, I learnt that tardigrades were the first animal to survive the vacuum of outer space, in 2007, as part of the FOTON-M3 space mission. Given their success in space, it seems these animals will certainly be part of future missions.
New Zealand tardigrades
The best way to collect tardigrades is by collecting bryophyte specimens. In the early 1970’s a scientist named Dr Donald Horning collected hundreds of bryophyte specimens during a New Zealand study of tardigrades. He described many new species for New Zealand. The holotypes for these species were placed in Te Papa’s invertebrate collection and the bryophytes were stored in the USA. In 2014 and 2015, The University of California Davis Herbarium donated Dr Horning’s bryophyte collection to Te Papa. It is these specimens which I am now databasing and adding to Te Papa’s botany collection. By databasing, I mean entering the specimen collection details into the museum database against a unique identification number.
Tardigrades – tiny time travellers
Before databasing and storing in the collection, plant specimens are first dried, then frozen – at minus 20 degrees C for 10 days. These environmental shifts suspend the metabolism of any tardigrades hitching within the specimens, putting them in a state of cryptobiosis. Normally short-lived tardigrades can survive, inactive, in this state for decades. In this way our botany bryophyte collection has become a vessel for tardigrades to transverse through time. This condition also makes them perfect potential space travellers and a version of cryptobiosis is often seen, replicated for humans, in science fiction.
Thank you to the University of California Davis Herbarium for gifting the bryophyte collection specimens.