Exoplanets

[ysabetwordsmith]

Mojave lichen defies death rays—could life thrive on distant exoplanets?

Lichen from the Mojave Desert can survive, and replicate, under levels of extreme solar radiation found on Earth-like planets in other solar systems.
Lichen from the Mojave Desert has stunned scientists by surviving months of lethal UVC radiation, suggesting life could exist on distant planets orbiting volatile stars. The secret? A microscopic “sunscreen” layer that protects their vital cells—even though Earth’s atmosphere already filters out such rays.


Yep. Lichen exemplifies one category of extremophile that you will find on exoplanets: small armored organisms. It's about as complex as life gets on most planets, being a multicellular organism comprised of algae and fungi.

You'll also find a lot of places with the equivalent of bacteria, algae, and other single-celled creatures. Less often, you might spot a miniature ecosystem in a moss-like plant with equivalents of rotifers, tardigrades, and such. Another rarity, but always worth testing for, are things like brine shrimp who leave desiccated eggs that hatch on contact with water.

This is because it's much easier for small, simple creatures to survive in harsh environments than it is for large, complex ones. Earth-like ecosystems are ultra-rare in most galaxies.  So that also tells you what to take along for terraforming.

Comments

[siliconshaman]

Tardigrades and now lichens, all of which are very archaic life forms. Which makes sense because conditions right here on Earth weren't always this good, and they've retained the adaptations that allowed them to survive.

Hmm.. so the Mojave lichens give us a base of a food pyramid, tardigrades are herbivores, we just need something that eats the tardigrades and can survive right alongside them, and you've got the start of a food web that can live on Mars... and if the predator species poops out something another hardy plant species can live on, you can really get things going.

Yes ...

[ysabetwordsmith]

>>Tardigrades and now lichens, all of which are very archaic life forms. Which makes sense because conditions right here on Earth weren't always this good, and they've retained the adaptations that allowed them to survive.<<

Exactly. Many extremophiles are quite old.

>> Hmm.. so the Mojave lichens give us a base of a food pyramid, tardigrades are herbivores, we just need something that eats the tardigrades and can survive right alongside them, and you've got the start of a food web that can live on Mars... <<

Predators include other tardigrades, amoebas, insect larvae, nematode worms, rotifers, oligochaete worms, mites, springtails, parasitic species of protozoa and fungi, etc. These vary considerably in hardiness.

For planets with highly variable conditions, I recommend experimenting with the wide array of "instant life, just add water" organisms. Some can dry out almost completely and then revive, like resurrection fern. Others lay eggs and then die; it is the eggs that can withstand harsh conditions, then hatch under favorable ones. Some have ways of encapsulating themselves, like certain mud mites. Just as one example, scientists took brine shrimp eggs out into space, exposed them to vacuum, brought them back to Earth and watered them. They hatched.

Life finds a way.