The jellylike creatures pulse along ocean currents and are abundant in cold and warm ocean water, deep water, and coastlines. Many people know jellyfish are one of those ocean creatures that look harmless but are anything except harmless. When you look past their stinging tentacles, jellyfish are one of the most fascinating creatures on our planet. You’re about to discover amazing things about the creature.
Guess how many species of jellyfish there are
Scientists used an estimation system to guess the number of jellyfish species in the unexplored ocean. They discovered some jellyfish that are so microscopic that they are practically invisible. However, they have been able to identify some jellyfish species.
Although the estimation is that there may be up to 3,000 jellyfish species, over 2,000 species of jellyfish have been discovered and identified. The smallest are those in genera Staurocladia and Eleutheria, measuring only 0.5 millimeters (0.02 in) in diameter.
They aren’t just essential prey
Although jellyfish are a food source for sea anemones, tuna, swordfish, sharks, sea turtles, and penguins, they are not always prey. They provide fatty acids to their predators but also capture prey and eat them, creating a dual role.
Jellyfish consume fish, shrimp, crabs, and tiny plants. Jellyfish use the stinging cells in their tentacles to paralyze their prey before eating them. Called nematocysts, these small compartments house a tiny, needle-like stinger. When you trigger it, the chamber opens, and venom shoots out.
Jellyfish are so old
Before the dinosaurs, trees, or even fungi, there were jellyfish. They are the oldest multi-organ animal, surviving all five of Earth’s mass extinction events. This includes the Great Dying, also known as the Permian-Triassic extinction event, which wiped out 70% of life.
Jellyfish are over 600 million years old. Some research has even suggested that jellyfish could be older, possibly 700 million years. Despite having no bones and, therefore, no fossils, scientists have dated them by looking for “soft fossils.”
Are there immortal jellyfish?
Most jellyfish only live for about a year, while some only live for a few days. But some jellyfish may be lucky enough to cheat death. This jellyfish species can return to life by creating younger versions of itself.
As scientists can tell, the Turritopsis dohrnii jellyfish might be immortal. Found in the Mediterranean Sea and the waters of Japan, this species can undergo cellular transdifferentiation, a process that reverts its cells to a polyp or adolescent stage. Wow!
Calling jellyfish ‘brainless’ isn’t an insult
Jellyfish do not need lungs, heart, or blood to absorb oxygen through their gelatinous skin. Some species of jellyfish have eyes and “teeth,” or relatively thin hairs that pull in and bite down on their food. In plain words, they don’t have brains.
Instead of a brain, jellyfish have an elementary nervous system with receptors that detect light, vibrations, and chemicals in the water. The key to their survival is their ability to blend in with the ocean, achieved with bodies of 98% water.