Description and Comments
The golden jellyfish are most closely related to the spotted jellyfish (Mastigias papua) that inhabit the nearby lagoons. They are similar to the spotted jellyfish in that they derive part of their nutrition from symbiotic algae (Zooxanthellae) that live in their tissues and part of their nutrition from captured zooplankton.
However, the golden jellyfish are morphologically, physiologically, and behaviourally distinct from the spotted jellyfish. They are easily distinguished from the spotted jellyfish by the almost complete loss of spots on the exumbrella and the almost complete loss of their clubs, an appendage attached to the oral arms.
Marine biologist Michael Dawson proposed that the golden jellyfish that inhabit Jellyfish Lake be classified as a subspecies (Mastigias cf. papua etpisoni) of the spotted jellyfish living in the nearby lagoons. The species identification is uncertain (denoted by cf. in the name) because the Mastigias papua local to Palauan lagoons may be only one of several cryptic species that make up the M. papua group, and in the future, the M. papua local to Palau may be identified as a separate species from other M. papua. He also proposed that the jellyfish living in four other Palauan marine lakes were distinctive enough to deserve recognition as unique subspecies.
This isn't actually one of my sightings, I've never been to Palau, but everybody knows about Mastigias Papua Etpistoni, so I thought it'd just be fun to do a post about them on the Jellywatch site.