Common name: upside down jellyfish

General information

The Upside-down Jellyfish, scientifically known as Cassiopea andromeda, is a unique species of jellyfish that is popular among aquarists for its peculiar behavior and appearance. Unlike most jellyfish that float freely in the water column, Cassiopea andromeda rests upside-down on the substrate, which allows the symbiotic algae living in its tissues to photosynthesize. This jellyfish has a mild sting and exhibits a beautiful, typically bluish or greenish translucent bell with white or pale spots.

Care

Keeping Cassiopea andromeda in a home aquarium requires a specialized setup to mimic their natural shallow, warm, and often mangrove-lined habitats. They need a sandy bottom where they can rest and sufficient lighting to support the photosynthetic needs of their symbiotic algae, known as zooxanthellae. It's important to maintain gentle water flow in the tank to prevent these jellyfish from being pushed around, as they are not strong swimmers.

Reproduction

Upside-down Jellyfish reproduce both sexually and asexually. In sexual reproduction, they release sperm and eggs into the water column, which develop into free-swimming larvae. Asexually, they can produce clones of themselves through a process called budding, where new individuals bud off from the adult's body.

Symbiosis

Cassiopea andromeda has a mutualistic relationship with zooxanthellae, which are photosynthetic algae. The algae provide the jellyfish with nutrients produced through photosynthesis, while the jellyfish offers the algae a safe place to live and exposure to sunlight, which is necessary for their photosynthesis.

Habitat

This species is typically found in calm, shallow waters such as bays, lagoons, and mangrove forests. They are distributed in warmer coastal regions of the Indo-Pacific, including parts of Australia, the Philippines, and the Red Sea.