A small bloom of jellyfish in mangrove waters in the east side of Singapore has drawn the attention of some members of the public.

Recent bloom

One EP Ang took to Facebook group Nature Society Singapore to share his sighting.

The jellyfish were spotted on the morning of Oct. 13 at Pasir Ris Park, near the mouth of the Sungei Tampines river.

Ang shared that at the time, the tide was rather high at around 2.4m, which could have made the sighting of the jellyfish more convenient.

Here are the numerous small, translucent blobs in the water.

One jellyfish — potentially the same species, Acromitus sp. — was also spotted in mangrove waters by a kayaker at Sungei Simpang on Aug. 31.

Previously seen in 2017 and 2019

This isn't the first sighting of mangrove jellyfish.

The invertebrates (creatures with no backbone) were last seen in large numbers in 2017 at Pasir Ris Park.

Here's a close-up of one from 2019.

However, they have also been seen at Chek Jawa, Sungei Buloh and other areas at Pulau Ubin.

These jellyfish are most distinguishable from their bell-shaped 'head' and fat tentacles.

The bell 'head' is around 6-8cm in diameter. The jellyfish also come in various colours such as white, brown, pink and purple.

Venomous?

Recent sightings of box jellyfish at Sentosa have sent Singaporeans into a tizzy.

Box jellyfish were first spotted in July and being highly venomous, an advisory was released by Sentosa Development Corporation to urge beachgoers to be more alert.

After another sighting on Oct. 10, Sentosa has restricted guests from entering waters at Siloso Beach until further notice.

Visitors should not attempt to touch jellyfish if they see any, and should alert other beach-goers and on-ground Beach Patrol Officers to its location.

If a person stung, they should not rub the affected area or use their fingers to remove the tentacles. Instead, they should contact BPOs or Sentosa rangers for first-aid assistance.

Though it is uncertain if the mangrove jellyfish are as venomous as the box jellyfish, it is unwise to touch them as well.

In response to Mothership's queries, the National Parks Board's Dr Karenne Tun, Director of Coastal & Marine at the National Biodiversity Centre, stated that they are aware of the jellyfish bloom.

They added that this species is commonly seen in Singapore's mangrove waterways, including Sungei Tampines, and is not known to be dangerous to humans.

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Top photo from EP Ang / FB