Stylaster (Order Stylasterina)
Welcome to the Stylaster genus landing page. In this section, you will find general information about this genus and tips on how to identify it. If you are looking to confirm an observation made with the Coral Finder, use the image browser below to verify what you saw underwater. Then click on the following link for further comparison with a similar genus: Distichopora.
The genus Stylaster is a member of the coelenterate class Hydrozoa, unlike most of the other coral genera described in the Coral Finder and Coral Hub, which are Anthozoa. Two key features of the Hydrozoans are (1) Generations alternate between a sexually reproductive medusoid form and an asexually reproductive polyp form, (2) Polyps are specialised, partitioning work, so that one polyp may deal with prey capture, whereas another polyp may focus on consuming the prey. Unlike Millepora however, Stylaster does not contain symbiotic algae, it is therefore termed azooxanthellate. For more information, check out the Hydrozoa page on Coral Hub.
- Coral Finder p. 2c, 3c, 29
- COTW – Vol 3 p. 402-403
Found in the Indo-Pacific and Atlantic Oceans.
Stylaster are distinctive, often pink or purple coloured corals. The colonies are branched, with the branches arrayed in a fan-like or planar arrangement. The branches are delicate and pointed. This genus lacks symbiotic algae and therefore is not reliant on sunlight for photosynthesis, as a result colonies are often found in shaded areas such as caves or at significant depths.
The polyps are arranged along the sides of the branches, and like Millepora the polyps are immersed in small pores. The polyps are arranged in an alternating pattern on the two sides of the branches giving a stepped pattern.
The Coral Finder lists Stylaster in one key group with other non-scleractinians, but only Distichopora, also a member of the Stylasterina, is a possible source of confusion. The two genera may be differentiated by examining the branches; Distichopora has thicker, blunter branches, whereas Stylaster’s branches are finer and form pointed tips.
Similar genus: Distichopora
Suggested Reading – Identification Tools
- Cairns, S. D. (1984). A generic revision of the Stylasteridae (Coelenterata, Hydrozoa). 2. Phylogenetic analysis. Bulletin of Marine Science, 35(1), 38-53.
- Cairns, S. D. (1985). 3 new species of Stylasteridae (Coelenterata, Hydrozoa). Proceedings of the Biological Society of Washington, 98(3), 728-739.
- Cairns, S. D. (1987). Conopora adeta, new species (Hydrozoam Stylasteridae) from Australia, the 1st known unattached Stylasterid. Proceedings of the Biological Society of Washington, 100(1), 141-146.
- Cairns, S. D. (1991). A generic revision of the Stylasteridae (Coelenterata, Hydrozoa). 3. Keys to the genera. Bulletin of Marine Science, 49(1-2), 538-545.
- Cairns, S. D. (1991). New records of Stylasteridae (Hydrozoa, Hydroida) from the Galapagos and Cocos Islands. Proceedings of the Biological Society of Washington, 104(2), 209-228.
- Cairns, S. D. (1995). New records of azooxanthellate stony corals (Cnidaria, Scleractinia and Stylasteridae) from the Neogene of Panama and Costa Rica. Proceedings of the Biological Society of Washington, 108(3), 533-550.
- Cairns, S. D., & Grantmackie, J. A. (1993). Review of the fossil Stylasteridae (Cnidaria, Hydrozoa) from the New Zealand Region. New Zealand Journal of Geology and Geophysics, 36(1), 1-8.
- Veron, J. E. N. (2000). Corals of the World. Melbourne: Australian Institute of Marine Science.
Suggested Reading – Other Topics
- Puce, S., Tazioli, S., & Bavestrello, G. (2009). First evidence of a specific association between a stylasterid coral (Cnidaria: Hydrozoa: Stylasteridae) and a boring cyanobacterium. Coral Reefs, 28(1), 177-177.