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Phylum Arthropoda > Subphylum Crustacea > Class Cirripedia
Volcano barnacle
Tetraclita sp.*
Family Balanidae
updated Mar 2020

Where seen? These large smooth barnacles are sometimes seen on our rocky shores, on large boulders where there is more water movement and where they are shaded from the sun at low tide.

Features: To about 3cm across. Outer shell thick, smoothly conical and not made up of plates. The outer shell has a ridged patten of bumps or short lines. The shell opening is rather small and the operculum recessed. Some were seen with an operculum with a pointed tip. The thick shell has an air-filled, honey-comb internal structure. This provides strength as well as insulation from the heat when exposed at low tide.

Pulau Sekudu, Mar 07

Operculum with pointed tip.

Thick shell with air-filled,
honey-comb internal structure.
Chek Jawa, Apr 02

Sisters Island, Jul 06

Pulau Hantu, Jul 03

Pulau Sekudu, Mar 07

Spot where a Volcano barnacle
used to be?

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

Volcano barnacles on Singapore shores
On wildsingapore flickr

Other sightings on Singapore shores

Terumbu Buran, Nov 10
Photo shared by James Koh on flickr.

'Feet' of the barnacle.
Changi West, Sep 20
Photo shared by Vincent Choo on facebook.

Links References
  • 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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