The upside down jelly fish (Cassiopeia xamachana Cassiopeia frondosa) has tentacles that have trichocysts and acquire energy from photosynthesis. In the daytime they swim upside down with their tentacles up facing the sun. To receive more sunlight they will congregate in the beach shallows and often get stuck when the tide goes out, ending up as “dried jelly fish” under the heat of the sun.

Upside down jelly fish are Cnidaria. They are in the genus Cassiopeia, with the species name Andromeda, called so because they are as nimble and graceful as a female celestial.

Upside down jelly fish are found in tropical waters all over the world. They mainly live in sandy environments from the tidal belt to where the water is around 10 metes deep. They don’t only use their tentacles to gain energy they also use them to catch plankton. The trichocysts on their tentacles are slightly toxic so it’s best to not get too close to the jellyfish.

On Dongsha Atoll the jellyfish are mainly found in the lagoon and occasionally can be seen on sea weed beds. They are not adept at swimming and in the slow flowing lagoon water they aren’t easily carried out to sea by the current. Another reason is that the nutrient salt in the water in richer than in the water outside the lagoon so the jellyfish prefer to stay where they are.

Translated by：Kevin Lax
Source：Marine National Park Headquarters