Photographs selected by Donny Bajohr

They’re among the Earth’s simplest creatures, composed of 95 percent water, with no spines, brains or hearts, but jellyfish still manage to capture our attention. Older than the dinosaurs, members of this group have been around for 500 million years.

Floating through the seas like a feather caught in the wind, jellyfish are almost mythical with their bioluminescent abilities—but don’t get too close. Their tentacles are also defense mechanisms that can sting potential threats. If you need to really see them, take a look here—from a safe distance.

a jelly and fish in the ocean
Smooch. A jellyfish and fish seemingly share a kiss. Joan Costa, Spain, 2014
a fish inside a jellyfish
Some small fish are immune to jellyfish stings and live among their tentacles, safe from potential predators and able to partake in the fish meals caught by the jellyfish. Lilian Koh, Philippines, 2018
These white jellyfish appear blue under a colorful spotlight.
These white jellyfish appear blue under a colorful spotlight. Alexandra Cearns, Australia, 2015

multiple jellyfish in the ocean
Jellyfish fossils are hard to come by because their soft tissue doesn’t leave skeletal remains, but traces of them have been found in sediment from 500 million years ago. Froilan Robas, Singapore, 2015
Under blacklight, the characteristics of a jellyfish glow in the dark.
Under blacklight, the characteristics of a jellyfish glow in the dark. Kenneth Renk, California, 2019
Jellyfish at an aquarium
Jellyfish come in a variety of colors, but they’re just as fascinating in black and white. Benjamin Cooper, China, 2018
Pacific sea nettles are seen from two different perspectives
Pacific sea nettles are seen from two different perspectives—over and under—each offering a view of their beauty. Jessica Gillson, California, 2021

a colony of spotted jellyfish can be seen in this sea during late summer.
Not far from a developed, urban area, a colony of spotted jellyfish can be seen in this sea during late summer. Reiko Takahashi, Japan, 2021
a jellyfish seemingly glows in the darkness of the sea
Above, lightning illuminates the night sky. Below, a jellyfish seemingly glows in the darkness of the sea; many jellyfish produce light through bioluminescence. Pham Huy Trung, Vietnam, 2021
Jellyfish in the ocean
Jellyfish defend themselves against humans, often unsuspecting ones who fail to notice them washed up on beaches, by stinging them with their tentacles. Albert Olle Callau, Spain, 2012

a sea anemone, which is related to coral, greets a florescent orange and yellow jellyfish
Seemingly growing from the rocky ocean floor, a sea anemone, which is related to coral, greets a florescent orange and yellow jellyfish. Viktor Lyagushkin, Russia, 2021
A couple of juvenile fish take shelter underneath the jelly’s umbrella
A couple of juvenile fish take shelter underneath the jelly’s umbrella while they all travel through the sea at night. Tom Shlesinger, Florida, 2020

longfin bannerfish nibble on a jellyfish
In waters off Qaruh Island, longfin bannerfish nibble on a jellyfish, possibly seeking tiny crustaceans that live alongside it. Suliman Alatiqi, Kuwait, 2022
translucent marine creatures swim in waters near the snowcapped Mount Vesuvius.
Two seemingly translucent marine creatures swim in waters near the snowcapped Mount Vesuvius. Marco Gargiulo, Italy, 2023

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Tracy Scott Forson is a senior editor at Smithsonian magazine.

Donny Bajohr is the associate photography editor at Smithsonian. You can follow him on Instagram @donny_bajohr.