🐾 Jellyfish

Jellyfish

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Who it is

• Scientific name: Phylum Cnidaria
• Family & relatives: Jellyfish are cnidarians, related to corals and sea anemones, and are not fish at all.
• How to spot it: A soft, see-through bell that pulses, with trailing tentacles that hang below.

Its body & abilities

• Size: Sizes range from tiny thumbnail species to giants with bells over 2 meters wide.
• Weight: Because they are almost entirely water, most are surprisingly light for their size.
• Body & adaptations: They have no brain, heart, or bones, and their bodies are about 95 percent water.
• Top speed: They are slow swimmers and mostly drift where the currents carry them.
• Strength: Their tentacles carry stinging cells that fire tiny harpoons to catch prey and defend themselves.
• Senses: They lack eyes and brains but sense light, gravity, and touch through simple nerve nets.
• Growing up: They have a two-stage life: a rooted polyp that buds off tiny young that grow into swimming bells.

Where it lives

• Habitat: They live throughout the ocean, from sunny surface waters to the cold deep sea.
• Where in the world: Jellyfish are found in every ocean on Earth.
• Territory: They hold no territory and travel wherever winds and currents push them.

What it eats

• Diet: They are carnivores that catch drifting animals with their tentacles.
• Favorite foods: They eat plankton, tiny fish, fish eggs, and other small sea animals.
• How it hunts: They drift with tentacles spread like a net, stinging and pulling in whatever bumps into them.

How it behaves

• How it moves: They move by squeezing their bell to push out water, gently pulsing forward.
• When it is active: Many rise toward the surface at night and sink deeper during the day.
• Family life: They can gather by the thousands in huge groups called blooms or smacks.
• How it talks: They do not communicate as we do, reacting instead to simple signals like light and touch.
• Babies: They reproduce both by releasing eggs and sperm and by budding new young from polyps.

Its place in nature

• Role in nature: They are important food for turtles and fish and help control plankton populations.
• Conservation: Jellyfish are widespread, and some blooms are actually increasing in warming, disturbed seas.
• Dangers: Sea turtles, sunfish, and some seabirds are among their main predators.

Life & legacy

• How long it lives: Most live less than a year, though one tiny species can reset its life cycle.
• In our culture: Their glowing, graceful drifting makes them favorite displays in aquariums around the world.
• Where to see it: You can see them in aquarium jelly tanks and sometimes drifting near beaches and piers.
• Fun fact: Jellyfish have no brain, no heart, and no bones, yet they've drifted the seas for millions of years!