Life in the Universe

What might life on other planets look like?

Do you imagine anything like this?

Credit: assembled by D. W. Hoard (2019) from images available online, relevant rights retained by copyright holders of the intellectual properties, presented here under the fair use provision for commentary purposes.

In modern times, our concept of what alien (or extraterrestrial) life might look like has been shaped by science fiction stories, movies, and TV shows. And also by our own perception of ourselves - the aliens that we imagine usually look and behave a lot like us!

But is there room in our imaginations for alien life that looks like the creatures shown below?

Giant tube worms (Riftia pachyptila)

Credit: BBC Wildlife in the Oceans [link]

Yeti crab (Kiwa hirsuta)

Credit: A. Fifis, Ifremer/ChEss, Census of Marine Life [link]

Vulcan Octopus (Vulcanoctopus hydrothermalis)

Credit: attribution unknown [link]

Scale worm (Nereis sandersi)

Credit: Philippe Crassous/Science Source; Discover Magazine [link]

All of these are actual examples of life in the Universe. They just don't live on other planets. Instead, they are found on Earth, around deep sea hydrothermal vents, which provide geothermal energy (heat) and organic and inorganic chemical compounds (nutrients) in an ecosystem mostly detached from the sunlight that ultimately powers life on Earth's surface and the upper oceans.

Subsurface oceans of liquid water are likely found on several planets and moons in our Solar System that are otherwise inhospitable for (surface) life.

The most common place for life to be found in the Universe might look like this:

Deep sea hydrothermal vent located at a depth of 2.25 km on the Juan de Fuca Ridge in the North Pacific Ocean off Vancouver Island.

Credit: NOAA [link]

Even though they are our Earthly cousins, these deep sea creatures all seem strange and alien!

But what should be our goals for finding life elsewhere in the Universe?

Are we only satisfied with complex - even intelligent - life?

Or should we be equally awestruck if we find extraterrestrial life similar to any of the following examples?

Moss (Bryophyte), a simple plant.

Credit: attribution unknown

Lichen (Letharia vulpina), an algae/fungus symbiote.

Credit: Jason Hollinger (Wikimeda Commons), CC BY SA 3.0 [link]

Bacterium (Escherichia coli), a simple animal.

Credit: Alissa Eckert and Jennifer Oosthuizen/CDC [link]

Amoeba (Amoeba proteus), a single-celled animal.

Credit: Wim van Egmond [link]