Osmoregulation and osmobiosis in the eutardigrade Richtersius coronifer

Morten Bjørn-Mortensen

Studenteropgave: Speciale


The osmoregulation capacity of the limno-terrestrial tardigrade Richtersius coronifer has been investigated. The animal’s ability to survive osmotic stress caused by saline and poly ethylene glycol (PEG) solutions has been investigated. Experiments showed that R. coronifer is a strong regulator, although the animal’s activity is affected at osmolalities higher than the normal haemolymph osmolality, which were found to be 168 ±18 mOsm. The response to saline and PEG- solutions differed, as salinity had a concentration dependent effect on survival, while PEG had an exposure time effect. Animals treated with PEG went into a tun formation equivalent to the tun associated with anhydrobiosis, while animals treated with saline solutions failed to subtract their legs. Osmolality measurements on single animals revealed good osmotic control at low salinities. No evidence of R. coronifer ability to enter osmobiosis was found, but osmotic stress caused by PEG triggered tun formation and could thereby indicate early cryptobiotic defense. The idea of osmotic stress functioning as an early warning system of cryptobiosis is supported in the literature. This could be of profound importance for cryptobiotic survival, as it gives tardigrades time to prepare for oncoming dry spells.

UddannelserMiljøbiologi, (Bachelor/kandidatuddannelse) Kandidat
Udgivelsesdato1 jan. 2006
VejledereHans Ramløv


  • Tardigrade
  • Water bear
  • Osmoregulation
  • Osmobiosis
  • Cryptobiosis
  • Richtersius coronifer