Papuan Spotted Jelly

The spotted jelly has distinctive spots atop its bell, and vary in colouration, from greenish blue to olive green, which can be attributed to the zooxanthellae which reside within their tissues. There are eight rhopalia on the bell's margin, which act as the sensory organs of the jellyfish.

They average around 10 cm (3.9 in) in diameter, but can grow as large as 30 cm (12 in).

They have 8 frilled oral arms, which end in a clublike appendage. The upper surfaces of these arms are covered in stinging cells called cnidocytes. Unlike many other jellies, spotted jellyfish have numerous mouths along the bottom of their oral arms.

Spotted jellies range throughout the Indo-Pacific, from the Fijian archipelago to the western Indian Ocean, and from Japan to Australia.

Some populations of spotted jellies in Palau have been found to occur in huge groups (called "smacks"), which have become tourist attractions. The most famous spot to admire them is the Ongeim’l Tketau Lake in Palau, also known as Jellyfish Lake.

These jellies feed on zooplankton and other tiny organisms using their cnidocytes. The spotted jelly has several small mouths used to grab animal plankton.

Spotted jellies also acquire much of their nutrition via an endosymbiotic relationship with photosynthetic zooxathellae, such as those of the genus Cladocopium. The zooxathellae provide the jellyfish with nutrients, and in return the zooxanthellae get a safe place to live. This symbiotic relationship is not unique to the spotted jellyfish, and can also be observed in species such as the upside-down jellyfish.

During the night, these jellyfish stay lower in the water column and migrate each day, rising to the waters surface, and following the sun east to west, to allow their zooxanthellae access to the light they need to photosynthesize.