1. Can tardigrades theoretically survive on Mars or on some of the recently discovered exoplanets?
Łukasz Kaczmarek & Madhu Kashyap Jagadeesh
1Department of Animal Taxonomy and Ecology, Faculty of Biology,
Adam Mickiewicz University in Poznań, Umultowska 89, Poznań, Poland
2Department of Physics, Christ University, Bengaluru , Karnataka, India

2. Tardigrada or water bears
Eutardigrada
- lacking of dorsal plates,
- lacking of cirri,
- two double claws on legs (most often),
- placoids in pharyngeal bulb present,
- terrestrial and freshwater (most often),
- ornamented or smooth eggs.
Heterotardigrada
- dorsal plates present,
- cirri present,
- four or more single claws or peduncles on legs (most often),
- placoids in pharyngeal bulb absent,
- terrestrial and marine (most often),
- smooth eggs.

5. On moss!

6. Tardigrades in extreme environments
Almost all terrestrial, freshwater and marine environments
deserts (also polar),
polar regions.
glaciers (cryoconite holes),
highest mountains,
bottoms of oceans.

7. Cryptobiosis Anhydrobiosis: Anoxybiosis: Chemobiosis: Cryobiosis:
occurs in situations of extreme desiccation
Anoxybiosis:
occurs in situations oxygen lack
Chemobiosis:
occurs in response to high levels of environmental toxins
Cryobiosis:
occurs in reaction to decreased temperature
Osmobiosis:
response to increased solute concentration

8. What can anhydrobiotic tardigrades withstand?
years under atmospheric conditions and up to 30 in frozen state
in liquid nitrogen (-253°C) (21 months),
at 151°C (15 minutes),
chemicals: carbon dioxide, hydrogen sulphide, methane, 1-hexanol, methyl bromide gas and 10 minutes in ethanol,
low pressure of the thermosphere and the amazing preassure up to 7,500 Mpa (74,019 atm.),
microgravity and lack of geomagnetic field
radiation: X-rays or heavy ions (4He) (LD50 = 5,000 Gy) and gamma rays (1,000 and 9,000 Gy),
UV radiation (75-88kJm-2 ) …

9. …also hydrated tardigrades can survive in extreme conditions: irradiation, preassure up to 100 MPa, temperatures down to -196oC and up to 38oC
‘‘ …a toughest animals on the Earth’’ (Copley, 1999).

10. Sleeping Beauty hypothesis
tested on rotifers, nematodes and tardigrades
time spent in anhydrobiosis is not counted to the animal total life span
higher fitness of animals and their offspring
Please imagine this amazing feeling when you wake up and you are still young and… you are on different planet or moon... or even in different planetary system!

11. Possible mechanisms protecting tardigrades
synthesis of trehalose,
heat shock proteins (HSP),
hydrophilic late embryogenesis abundant (LEA) proteins,
cytoplasmic abundant heat soluble (CASH) proteins,
secretory abundant heat soluble (SASH) proteins
mitochondrial abundant heat soluble (MASH) proteins,
reactive oxygen species (ROS),
removal of damaged/dysfunctional molecules,
and…some morphological and behavioural adaptations

12. Tardigrades in the space
TARDIS (TARDigrada In Space)
TARSE (TArdigrade Resistance to Space Effects)
RoTaRad (Rotifers, Tardigrades and Radiation)
TARDIKISS (Tardigrades in Space)

13. Survive on Mars Survive: probably YES Active live: probably NO
solar wind
cosmic radiation (ionizing radiation)
almost lack of atmosphere
lack of oxygen
lack of geomagnetic field
microgravity
low atmospheric pressure
low temperatures down to −143 °C
„high” temperatures up to 35 °C
dust storms
lack of liquid water
soil pH = 7.7
lack of food
cryptobiotic
cryptobiotic,
active
cryptobiotic
cryptobiotic
cryptobiotic,
active?
Survive: probably YES
Active live: probably NO
cryptobiotic
cryptobiotic
cryptobiotic
cryptobiotic,
active
cryptobiotic
cryptobiotic
But some of algae can also survive in martian condition…
and they are perfect food for tardigrades!!!
cryptobiotic,
active

14. Tardigrade Similarity Index (TSI)
radius 0.5 to 1.9 EU,
mass 0.1 to 10 EU,
density 0.7 to 1.5 EU,
surface temperature ca. 1 to 424K
escape velocity 0.4 to 1.4 EU.
gravity as 0.16 to 17 EU
revolution as 0.61 to 1.88 EU
Schulze-Makuch, D., et al. (2011). Astrobiology, 11, 1041.
2017. J. M. Kashyap. Draft version February 14, 2017 Preprint typeset using LATEX style AASTeX6 v. 1.0

15. Active and Cryptobiotic Tardigrade Index (ATI, CTI)
Figure 1. The values of ATI (Active Tardigrade Index) for 40 rocky-water exoplanets,19 water-gas exoplanets, and our Solar System objects.
Figure 2. The values of CTI (Cryptobiotic Tardigrade Index) for 40 rocky-water exoplanets,19 water-gas exoplanets, and our Solar System objects.

16. Active and Cryptobiotic Tardigrade Index (ATI, CTI)
The best candidates are:
TRAPPIST-1 b,
Mars,
Kepler-114 d,
Kepler-138 d,
GJ 1214 b,
Kepler-445 c, TRAPPIST-1 f.
Figure 3. The values of the combined ATI (Active Tardigrade Index) and CTI (Cryptobiotic Tardigrade Index) for 40 rocky-water exoplanets,19 water-gas exoplanets, and our Solar System objects.

17. Conclusion
Tardigrades in cryptobiotic state can probably survive not only on Mars, but also on some of recently discovered planets.

18. Thank you…also for your attention 
I want to thank:
My parents (they know for what);
Tardigrades because they are so cute and amazing;
My students: Weronika, Krzychu, Milena, Marta and few others (thanks to them I have enthusiasm for further work);
and my colleagues (especially dr Bartłomiej Gołdyn who is my co-lecturer in the course of the Astrobiology).
Thank you…also for your attention 