ascidians text index | photo index
Phylum Chordata | Subphylum Tunicata/Urochordata | Class Ascidiacea
Thumbs-up sea squirt
Polycarpa sp.*
Family Styelidae
updated Oct 2016
Where seen? This blob with a thumb and red stripes is commonly seen our Northern shores. Like some odd disembodied thumbs-up, this animal is usually stuck to a large boulder, jetty pillings and other hard surfaces, near the mid-water mark. Usually seen alone or in groups of a few individuals.

Features: 3-5cm long, made up of two 'fingers', one shorter and at right angles to the longer larger 'finger'. Usually white with orange or red irregular broad stripes. It is a solitary (not colonial) ascidian. It appears sad and flaccid when exposed out of water, but is usually well rounded when submerged.

It has bands of muscles along its body. When these muscles constrict, water squirts out. That's why it is called a sea squirt. It does this when disturbed, or to get rid of wastes.

They settle near the low water mark
at the base of rocks.
Changi, Jun 02

Tuas, Dec 03

Tanah Merah, Oct 09

Chek Jawa, Jul 03

Tanah Merah, Jul 11

*Species are difficult to positively identify without dissection and examination of internal parts.
On this website, they are grouped by external features for convenience of display .

Thumbs-up sea squirts on Singapore shores

Photos of Thumbs-up sea squirts for free download from wildsingapore flickr

Distribution in Singapore on this wildsingapore flickr map

Pasir Ris, Jul 17
Photo shared by Teo Say Chong on facebook.


  • Lim, S., P. Ng, L. Tan, & W. Y. Chin, 1994. Rhythm of the Sea: The Life and Times of Labrador Beach. Division of Biology, School of Science, Nanyang Technological University & Department of Zoology, the National University of Singapore. 160 pp.
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