Amakusa Jellyfish (Sanderia malayensis)
Amakusa (Sanderia Malayensis) are a common jellyvorous jellyfish seen in South coast of Japan in summer. They are commonly seen in captivity because they are relatively easy to keep. Amakusa jellyfish have 32 lappets, 4 oral arms and 16 very long tentacles coming out from the bell. Their colour varies from brown to white. The dots seen on their bells and tentacles are the lumps of nematocysts. Their sting is very strong and it can kill a small fish in seconds. However, captive bred Amakusa jellyfish seem to have weaker stings, and compared to wild specimens, they don’t cause serious harm to human. The tentacles are very long and are beautiful when they are fully extended. Therefore they must be kept together in relatively small density to ensure the tentacles do not tangle with each other. Usually seen in public aquariums, Amakusa jellyfish are rarely kept by hobbyists though their husbandry should be possible by moderately experienced jellyfish keepers.
Harmful to humans: Partially – Stings from captive bred species are usually undetectable, however may cause irritation to those with sensitive skin
Distribution: East China Sea to South of Japan
Maximum Bell Size: 20 cm (8 inches)
Life Span: 1 year
Feeding: Moon jellyfish, mysids, small fish
Temperature: 18 – 24°C (68 – 79°F)
Care level: Moderate
Notes: The sting seems weaker in captive bred ones compared to wild ones. They grow very quickly when fed on moon jellyfish and can easily double the size in a week. The mechanism of how they distinguish their own species from other species of jellyfish remains unknown.