The moon jellyfish (Aurelia aurita) is one of the ocean’s most ethereal creatures — a pulsing translucent disc that drifts through the water column, trailing delicate tentacles. Nearly 95% water, jellies are among the simplest multicellular animals alive — yet they have thrived in Earth’s oceans for over 500 million years.
No Brain. No Heart. No Problem.
Moon jellyfish have no brain, heart, blood, or bones. Their nervous system consists of a simple nerve net — a diffuse network of cells capable of detecting light, gravity, and touch. Despite this apparent simplicity, jellies are masters of their ecological niche.
Their translucent bells reveal the four distinctive horseshoe-shaped gonads (reproductive organs) that give moon jellies their name.
The Bloom Phenomenon
Jellyfish can bloom in extraordinary numbers — millions of individuals in a single aggregation. Ocean warming, reduced predator populations, and coastal eutrophication all favor jellyfish population explosions. Some researchers believe we are entering an era of increasing jellyfish dominance in warming, nutrient-enriched coastal seas.
At the Alaska SeaLife Center
Our jellyfish display is one of the most mesmerizing in the Center — a darkened gallery where moon jellyfish drift in illuminated kreisel tanks. These circular tanks create a gentle current that keeps jellyfish suspended without injuring their delicate bells. Visitors often spend extended time simply watching jellies pulse — a meditative, profoundly calming experience.
Moon jellyfish make surprisingly complex exhibit animals: they require precise water quality, specialized feeding, and careful tank design. Our aquarists raise jellies through their full life cycle — from the fixed polyp stage through ephyra (baby jellies) to adult medusae.