Why do deep-sea animals look so different?

Who are you calling weird?

The deep sea is practically a world of its own—it’s cold, it’s pitch black, and the water pressure is so intense, human bodies would not survive it. This extreme environment has forced deep-sea animals to evolve in order to survive. And some of those adaptations make deep-sea animals appear strange to our human eyes.

But aquarist Tommy Knowles begs to differ. “They’re not weird. They’re perfectly adapted for their environment,” Tommy says. He and fellow Aquarium biologists Mackenzie, Alicia, and Ellen share more about the adaptations these incredible creatures use to survive in the deep sea and answer the question: Why do deep-sea animals look so different?

Color me amazed

In the pitch black darkness of the deep sea, color plays a vital role in animals’ survival. Many animals in the deep sea are transparent, which helps them remain hidden from their predators. Others are bright red. This works as excellent camouflage for these creatures, as most deep-sea animals cannot see the color red. Without red light, one cannot see the color red. Since red light doesn’t reach the deep sea, red animals like these look black and are invisible to most predators.

Eye see you

It is vital for some animals to be able to see in the deep sea. Some predators, such as the owlfish, have really big eyes, and are able to pick up little bits of visible light that make it down to the deep sea. These eyes are vital in helping deep-sea creatures find prey, search for mates, and be on the lookout for predators. 

Hunt or be hunted

We all have to eat to survive. The creatures that live in the deep sea will eat a wide variety of prey—often, they have to eat what they can find! Since food is often scarce, some deep-sea animals are able to expand their stomachs to store food, which digests for about a month. These creatures consume very large prey, and therefore do not have to hunt as often. Other fish, such as the anglerfish, have a lure to attract prey to them.

“For us, we think, woah, those animals are so weird looking, like why do they look like that? But I’m sure they would look at us and be like, ‘why do they look so weird?’” Ellen Umeda states. After learning about these amazing adaptations it begs the question: What if we’re the weird ones?

Can't get enough of deep-sea creatures? Learn more about the fascinating animals featured in this video from our colleagues at MBARI.