Caribbean Upside-down Jellyfish

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Species group:

Other common names: Suction Cup Jellyfish, Upside-down Sea Jelly

Scientific name: Cassiopea xamachana

The basics:
The Caribbean Upside-down Jellyfish is ideal for experienced aquarists as it need not be kept in the specially-designed circular tanks critical to success with other Jellyfish, and is easier to feed than related species.

The Caribbean Upside-down Jellyfish is found in the southwestern Atlantic Ocean, throughout the Caribbean, and in the Gulf of Mexico. It inhabits the shallow, quiet waters of mangrove swamps, back bays, canals and lagoons, and is often found in large groups.

Appearance / health:
This attractive jellyfish is bluish-gray to blue-green in color, and reaches 25 cm (10 in) in diameter. Although it can rise into the water column and “swim”, the Caribbean Upside-down Jellyfish generally secures itself to the bottom, using the top of the bell as a suction cup. The many-branched tentacles extend upward into the water to gather prey.

The Caribbean Upside-down Jellyfish is among the hardiest of all jellyfishes, but still quite delicate. Improper placement in the aquarium (see below), poor lighting, and an insufficient diet are the most common causes of fatalities. Jellyfishes cannot tolerate copper-based medications, ammonia, or nitrites.

Behavior / temperament:
The Caribbean Upside-down Jellyfish generally remains in one spot, but may relocate if food or light are in short supply. Its sting is considered mild, but induces an itchy irritation; the possibility of individual sensitivities or allergic reactions must, however, be considered. Jellyfishes are best housed with others of their kind, as their stings can injure or kill various invertebrates and fishes.

It is critical that Caribbean Upside-down Jellyfish be positioned so that they receive the flow from moderate water currents, so that food will be carried within reach. They also require powerful lighting, so that the symbiotic zooxanthellae (single-celled protozoans), which provide the jellyfish with nutrients, can thrive. The aquarium should be provisioned with live sand and live rock, which may generate supplementary food in the form of micro-organisms.

The following water quality parameters should be maintained for Caribbean Upside-down Jellyfishes: Specific Gravity (Salinity): 1.020-1.025; Temperature: 24-28 C (75-82 F); pH: 8.1-8.4; Alkalinity 8-12 dKH; Calcium, iodine and other trace elements should be added as suggested by the product manufacturer.

In addition to the nutrients produced by the photosynthetic zooxanthellae, Caribbean Upside-down Jellyfish should be provided large daily feedings of newly-hatched brine shrimp. Brine shrimp should be nutritionally enriched with a commercial algae-based diet designed for that purpose (i.e. Selco) beforehand. They may also derive some benefit from plankton formulas designed for use with filter-feeding marine invertebrates.

Caribbean Upside-down Jellyfish reproduce sexually and asexually, going through several stages that differ greatly in appearance and lifestyle before becoming an adult, or medusa. Survival of the larval stages seems to depend upon a ready availability of plankton-based foods.

Written by Frank Indiviglio

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