Cassiopea Jellyfish

jellyfish · ocean · weird behavior

Upside-down dwellers. Cassiopea jellyfish spend their lives resting upside-down on the sea floor in shallow water. They do this because they have a special partnership with tiny organisms inside their bodies that need sunlight to survive.

Algae helpers inside. These jellyfish have a symbiotic relationship with photosynthetic dinoflagellates, which are tiny living things that use sunlight to make food. By lying upside-down, the jellyfish help their algae get enough light, and the algae give the jellyfish nutrients in return.

Sleeping without a brain. Cassiopea jellyfish appear to sleep even though they have no brain, which is truly strange and mysterious. Scientists study them to understand what sleep really means for creatures so different from us.

Rainbow of colors. In areas where cassiopea live, you might find them in white, blue, green, brown, and other shades depending on the algae inside them. Each color tells you something different about what's living in that jellyfish's body.

Toxic mucus protection. Cassiopea jellyfish have poisonous proteins in the mucus on their skin, which helps protect them from predators and other dangers in the ocean.