wildsingapore homepage wildfactsheets homepage wild shores of singapore blog

Slender sea pen Virgularia sp.* Family Virgulariidae updated Aug 10 Where seen? Often mistaken for a stick stuck in the sand, this elegant colony of animals is commonly encountered on our Northern shores. On silty sand and mong seagrasses. Features: 15-20cm long. Primary polyp stiff, long and slender. Leaf-like structures are short (1-2cm), without spikes on the edges. Tiny secondary polyps are found on these leaf-like structures. The primary polyp usually can only be seen on one side of the animal. On the other side, the leaf-like structures obscure the stalk. The primary polyp ends in a bulbous foot that is buried in the sand. Colours seen include red, maroon, orange, purple and white. When exposed at low tide, the leaf-like structures are collapsed, while the stiff central primary polyp remains upright. So the colony looks like a thin stick stuck in the ground. Sometimes, the central stalk is retracted into the ground, resulting in a ruffle of secondary polyps left peeping out at the surface. Pen pals: Slender sea pens are recorded to harbour small creatures such as porcelain crabs, shrimps, brittle stars and small nudibranchs. The Painted porcelain crab (Porcellanella picta) have been spotted on the Red slender sea pen.

Primary polyp partially retracted into the ground. Beting Bronok, Aug 05 Secondary polyps on the leaf-like structures.

Transparent shrimp at top left corner, only its eyeballs barely discernable Beting Bronok, Aug 05

A pair of Painted porcelain crabs on the sea pen. Beting Bronok, Aug 05

Chek Jawa, Jun 06

Changi, Jul 06

Changi, Jul 05

Changi, Aug 11

Changi, Aug 11

Changi, Aug 11

more photos of slender sea pens on Singapore shores
part 1 | part 2 | part 3 | part 4