Upside Down Jellyfish

Cassiopeia sp

About This Animal

SIZE: Up to 12 inches in diameter

RANGE: Shallow, coastal, tropical waters, Indo-Pacific, Caribbean, Gulf of Mexico, and Hawaii

HABITAT: Shallow coastal waters; sandy or muddy seafloor areas like sea grass beds and mangrove swamps

DIET: Some small plankton, but primarily photosynthetic deriving much of it food from symbiotic algae

Unlike most other jellies, this species rests upside-down on the sea floor and rarely swims. By lying upside-down, the jelly exposes its algae to the sun, allowing it to photosynthesize. The jelly lives off food the algae produce, as well as zooplankton.  This jelly is rarely found alone — it flips upside-down alongside others of its kind. With stubby oral arms pointed toward the sun, the jelly looks like a flower.  When disturbed these jellies can release strings of mucous containing stinging cells as a defense mechanism. 

Upside down jellies are commonly found basking in mangrove swamps and sea grass beds.  These habitats are two of the most threatened habitats on Earth.  They are easily damaged by human activities and coastal development.