Humans have a habit of making everything about them. Animals are compared to humans, seen in relation to them, evaluated according to how well or how badly they stack up to human capabilities. Are they useful in some way? Can we eat them, ride them, turn their bodies into clothing or weapons, vehicles or houses?

Environments, same thing. Can we live there? Is it comfortable for us? If not, how do we alter it to fit? When we imagine living in it, we impose human standards on it.

Even when we’re trying to stay objective, when we’re describing a creature or a place that’s not perfectly human-friendly, we still talk about it in human terms. It’s about making it relatable. A whale is as big as a bus or as long as X fraction of a football field. The depths of the ocean are horribly dark and cold and the pressure is crushing. It’s totally alien and inhospitable.

Science fiction can challenge us to change the way we think. Question our assumptions. Reorient ourselves to a different world. Embrace the alien, and try to understand it on its own terms.

When we think alien, we tend to think extraterrestrial. Something not from this planet. And yet parts of this world are, by human standards, downright weird. More than two-thirds of its surface is covered in water, some of it literally miles deep. We’ve only just begun to realize how much is down there.

The deepest part of any ocean is the Mariana Trench in the Pacific, which goes down as far as 36,000 feet (11,000 meters). There’s no sunlight below 1200 feet (365 meters), and no light at all past 3300 feet (1000 meters), except what organisms may generate through bioluminescence. The water pressure increases tremendously. Plants can’t grow down there. It’s all animals, all the way down, clear to the bottom.

Life has evolved for these conditions. Organisms feed on each other, or on the rain of organic matter from above, everything from microorganisms to the bodies of deceased whales that sink down and down to nourish an amazing variety of creatures. There’s a kind of worm called the zombie worm or bone worm that lives on the fat inside the bones. Talk about the human perspective: there’s nightmare fodder there, creepier than secret government installations or prehistoric mega-sharks or alien invaders lurking in the depths.

I happened across a meme from the site formerly known as Twitter, from 2023, by someone named Victoria:

At a certain ocean depth every creature is either: MURDERFANG: a 3-foot-long fish with bioluminescent teeth that looks like it’s from ALIEN Sea Friend: a 1-inch-long jellyfish that propels itself around with cute little farts. it’s always smiling, it’s god’s favorite little guy

To which a poster named gravityeyelids replied,

#also murderfang is completely safe but touching sea friend for 0.01 s[econd] can kill 500 people

which may be a bit of an exaggeration (or maybe not), but there are some really scary things down there, and the ones that look the scariest aren’t necessarily the most dangerous. Like the anglerfish down around 6500 feet (2000 meters) with her little head lantern and her enormous snaggly teeth and the tiny little polyp that’s what’s left of her husband after he literally joined with her to make baby anglerfish. She’s deadly to other fish, but she’s not death to all that lives.

Down below the realm of the anglerfish, the deadly gives way to the weirdly cute. The deepest of all the deep-sea octopuses, the dumbo octopus, lives around 10,000 to 13,000 feet (2000 to 3000 meters) and has been found as far down as 23,000 feet (7000 meters). This species of octopus has a different mouth structure than its relatives; it swallows its prey whole rather than biting or grinding it. Its body has an internal structure of cartilage that supports it at the crushing pressure of the depths; unlike shallow-water octopuses, it can’t squeeze through minuscule openings. A pair of earlike fins propel it through the water (hence the reference to the Disney elephant with the flying ears).

The dumbo octopus shares its range with a downright adorable fish, the snailfish. These are the deepest of all deep-sea fish that we’ve come across so far. They’ve been found all the way down to 26,000 feet (8000 meters).

They’re a soft, tadpole-like fish, with a smooth or bumpy skin, and a big head with a sucker on the underside, for attaching to the sea bottom or a suitable surface. They aren’t very big, a foot long (30 centimeters) at the most. And there are a lot of them, over a hundred different species, with more being discovered as scientists explore the deepest of the deep sea.

From the human point of view, these creatures live in a hell of darkness, cold, and brutal pressure. But when we’re lucky enough to get video, they look perfectly cheerful, swimming along and living their lives in a world as alien to us as the storms of Jupiter. It’s home to them. They’re adapted to it. They belong there.

Someday we may encounter life on other planets, and find even more amazing and wonderful variations. But until we get there, there are whole worlds to discover on our own planet, new forms of life, new species, new versions of those we’ve met before. Some of them live in environments that we would never have imagined, in conditions that we once considered inhospitable to life—the bottom of the ocean, the areas around hydrothermal vents. It’s illuminating, and humbling, to realize how little we really know of what’s down there, and how much there still is to learn.