Australian Biological Resources Study

Australian Faunal Directory

Images of stylasterid coral fields in Antarctica.

Images of stylasterid coral fields in Antarctica.

Images of stylasterid coral fields in Antarctica.

Images of stylasterid coral fields in Antarctica.

Images of stylasterid coral fields in Antarctica.

Images of stylasterid coral fields in Antarctica.


Regional Maps

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Family STYLASTERIDAE Gray, 1847

Hydrocoral, Lace Coral

Compiler and date details

15th of December 2017 - Narissa Bax (PhD) holds an Adjunct Researcher position at the Institute for Marine and Antarctic Studies (IMAS). Her PhD thesis focused on stylasterid corals in the deep sea in Antarctica, and she continues to work on all aspects of deep sea coral biogeography, phylogenetics, connectivity and conservation. Her current project collaboration is Antarctic Seabed Carbon Capture Change (ASCCC), as part of the Antarctic Circum-navigation Expedition (ACE). For more information on this project visit the following website: and please feel free to email: if you have any queries regarding stylasterid corals.


Stylasterid corals are calcified, often colourful, colonial hydrozoans of the phylum Cnidaria, commonly called lace corals or hydrocorals. Colonies are erect, branched, usually flabellate, rarely encrusting, with a thick calcareous exoskeleton, termed the coenosteum. Coral polyps can be polymorphic and retractile. Gastrozooids, polyps specialised for feeding, are commonly composed of one whorl of filiform tentacles (rarely without tentacles), and the bottom of the gastric cavity may contain upright pointed or rounded toothed spines termed gastrostyles. Dactylozooids, polyps specialised for capturing prey, are filiform, without tentacles and maybe with or without dactylostyles. Gastrozooids and dactylozooids are retractable into special skeletal depressions termed gastropores and dactylopores. These gastrozooids and dactylozooids are either irregularly distributed over the entire colony, limited to certain regions, or often arranged in circles, termed cyclosystems. A cyclosystem is composed of one central gastrozooid surrounded by several dactylozooids. Gonophores, are specialised for reproduction, and are composed of reduced fixed sporosacs which develop inside vesicles, termed ampullae, covered by or buried in the coenosteum (Cairns, 2011).

The most likely method of reproduction in stylasterids involves brooding larvae that settle close to adult colonies. Brook and Stone (2007) found that most stylasterids were classified as gonochoristic (separate sexes) brooders. Therefore, the known reproductive modes exhibited in stylasterid corals are indicative of limited dispersal potential often associated with highly structured, patchily distributed, isolated populations.

Stylasterids are a predominantly deep water family (only 10% of species are in waters shallower than 50m, Cairns, 1992) and they are entirely azooxanthellate (Cairns 2011). Three hundred and fourteen species are described world-wide, the majority from the Southern Hemisphere (Cairns, 2015). Their aragonite or calcite skeleton (Cairns & MacIntyre 1992), gross branching morphology, relatively large size, and their association with commensal invertebrates (e.g., polychaetes and asteroids) make stylasterids an important component of the deep-sea fauna globally. However, since stylasterids occur in deep and predominantly colder waters, they are difficult to study so new species are likely to be discovered as deep sea sampling increases (Bax, 2015). There are 35 stylasterid genera listed in WoRMS (including fossil taxa).

The following species of Stylasteridae have been recorded in Australian offshore waters and are listed in order of morphological complexity as defined by Cairns, (1988):

Sporadopora dichotoma sensu Hall, 1898 †
Distichopora violacea (Pallas, 1766)
Distichopora coccinea Gray, 1860
Distichopora nitida Verrill, 1864
Distichopora sp. sensu Hall, 1898 †
Stylaster marshae Cairns, 1988
Stylaster sanguineus Milne Edwards and Haime, 1850
Stylaster granulosus Milne Edwards and Haime, 1850
Stylaster gracilis Milne Edwards and Haime, 1850
Stylaster incompletus (Tenison-Woods, 1883)
Stylaster mooraboolensis (Hall, 1893) †
Stylaster tenisonwoodsi Cairns, 1988
Conopora adeta Cairns, 1987
Crypthelia pudica Milne Edwards and Haime, 1849

† exclusively fossil species

List of Antarctic stylasterid corals found in Australian Antarctic Territory (Bax and Cairns, 2014):

Errina fissurata, Gray, 1872
Errina gracilis von Marenzeller, 1903
Errina laterorifa Eguchi, 1964
Inferiolabiata labiata (Moseley, 1879)

From the Antarctic region, four Australian Antarctic stylasterid species have been recorded in field-like aggregations (images attached): Errina fissurata, Errina laterorifa, Errina gracilis>/i> and Inferiolabiata labiata. The recent discovery of these aggregations has highlighted the importance of deep-sea stylasterid coral populations in the Southern Ocean (Post et al., 2010). Subsequently, an area of dense coral aggregations has been listed as a Vulnerable Marine Ecosystem (VME) by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) (Bax and Cairns, 2014).

Note on Hydrocoral classification:

There are two coral families known commonly as hydrocorals, the Stylasteridae and the Milleporidae. These coral families secrete a calcium carbonate skeleton, and therefore look superficially like cnidarian corals. However, they are hydrozoans - hence the name hydrocoral. Their affinity as hydrocorals was first documented by Agassis (1858) and Moseley (1879), the two were combined in a single order, Hydrocorallina, until Boschma (1956) when they were assigned to the orders Stylasterina and Milleporina (where they are often found in field guides). However, there has been sufficient debate since this time to place them in the suborders of Filifera (Stylasteridae) and Capitata (Milleporidae), order Anthomedusae. (See also under Milleporidae). Stylasteridae is considered monophyletic within Hydrozoa, based on genetic studies (Cartwright et al., 2008), adding further support to their current systematic placement.

The world's foremost expert on stylasterid corals is Dr Stephen D Cairns. His many publications can be found here:


Ecological Descriptors

Hydroid and medusa stages: colonial (host(s): polychaete worm; Pedicularia sea snail).


ID Keys

Keys to the stylasterid genera can be found in the following publications:

Cairns, S. D. (1983). A generic revision of the Stylasterina (Coelenterata: Hydrozoa). Part 1. Description of the genera. Bulletin of Marine Science, 33(2), 427-508.

Cairns, S. D. (1984). A Generic Revision of the Stylasteridae (Coelenterata: Hydrozoa) Part 2: Phylogenetic Analysis. Bulletin of Marine Science, 35(1), 38-53.

Cairns, S. D. (1991). A generic revision of the Stylasteridae (Coelenterata: Hydrozoa). Part 3. Keys to the genera. Bulletin of marine science, 49(1-2), 538-545.

For a pictorial reference guide see:

A glossary of terms edited from Cairns (2011) to describe the main stylasterid morphological characters:

Abcauline and Adcauline Dactylopore Spine: See Dactylopore Spine.

Ampulla (Ampullae): The skeletal encasement of the reproductive unit (see gonophore). Most commonly, superficial female ampullae release their planulae through a lateral efferent pore or tube, smaller male ampullae release their sperm through apical pores.

Ampullar Formula: See Ampulla.

Cheval-de-frise: See Gastropore Tube.

Coenosarc: The network of canals that connect polyps.

Coenosteum (Coenosteal, adj.): The calcium carbonate skeleton of the stylasterid, usually aragonitic, but occasionally calcitic or partially calcitic (Cairns and Macintrye, 1992). Often described as 1) Linear imbricate, or 2) reticulate-granular.

Composite Dactylopore Spine: See Dactylopore Spine.

Compound Dactylopore Spine: See Dactylopore Spine.

Corallum: The calcareous skeleton of the entire colony.

Cyclosystem (Cyclosystemate, adj.): A functional unit of stylasterid colony structure composed of a central gastropore (gastrozooid) surrounded by a variable number of dactylopores (dactylozooids).

Dactylopore: The surface pore associated with a dactylozooid.

Dactylopore Spine: A projection from the coenosteum, U- or horseshoe-shaped in cross section, that is usually adjacent to a dactylopore. If the lateral slit (dactylotome) of the dactylopore spine is directed toward the distal branch tip, it is termed abcauline; if it opens toward the proximal end of the branch, adcauline.

Dactylostyle: A row or crowded multiple rows of small cylindrical pillars (elements) that occur on the outer wall of the dactylopore tube.

Dactylozooid: One of the three types of stylasterid polyps, which specializes in defense and aiding in food acquisition, each dactylozooid composed of a simple mouthless tentacle.

Double-Chamber Gastropore Tube: See Gastropore Tube.

Efferent Duct: See Ampulla.

Efferent Pore: See Ampulla.

Gastropore (also called Gastrostome): The surface pore associated with a gastrozooid, usually round, slightly elliptical, or stellate in shape (e.g., Stellapora sp.); occasionally bordered by a triangular, abcauline lip.

Gastropore Ring Constriction: See Gastropore Tube.

Gastropore Tube: The tube that contains the gastrozooid, usually a simply straight cylinder, but often curved, and in some genera, a double-chambered cavity (e.g., Conopora sp.), the upper and lower chambers separated by a gastropore ring constriction. Gastropore (and dactylopore) tubes are usually fairly short and oriented perpendicular to the branch surface, termed peripheral gastropore tubes. Some genera have a ring or girdle of small cylindrical elements that project from the wall of the gastropore tube near the level of the gastrostyle tip, this structure called the ring palisade)(also called the cheval-de-frise).

Gastrostyle: The vertical, spinose, axial structure that projects from the base of the gastropore tube in various genera. Although usually lanceolate in shape, it may assume a variety of other shapes.

Gastrozooid: One of the three types of stylasterid polyps, which specializes in obtaining food, and usually containing a ring of filiform tentacles encircling a mouth.

Gonophore: One of the three types of stylasterid polyps, this one housing the reproductive structures, i.e., sperm or egg. Most species are dioecious, each colony being either male or female, only one species known to be hermaphroditic (Stylaster roseus).

Internal Ampulla: See Ampulla.

Linear-Imbricate Coenosteal Texture: See Coenosteum.

Lip, Gastropore: See Gastropore.

Nematophores: Concentrations of large nematocysts, often located at the edge of cyclosystems, on pseudosepta, or on cyclosystem lids. Nematopores are the shallow skeletal pits that house the nematophores.

Nematopores: See Nematophore.

Planula (Planulae): The specialised larval stage of a cnidarian. All stylasterids are brooders, releasing their planulae at an advanced stage (see Stratford, 2002; Miller et al., 2004).

Platelet: The branch coenosteum of a species having linear-imbricate texture is composed of imbricating platelets.

Pseudoseptum (Pseudosepta): The roughly triangular-shaped coenosteum that separates the dactylotomes in a cyclosystem.

Reticulate-Granular Coenosteal Texture: See Coenosteum.

Ring Palisade: See Gastropore Tube.

Shelf, Gastropore: See Gastropore.

Slit, Coenosteal: See Coenosteum.

Strip, Coenosteal: See Coenosteum.

Superficial Ampulla: See Ampulla.


Cairns S.D., MacIntyre I.G., (1992) Phylogenetic implications of calcium carbonate mineralogy in the Stylasteridae (Cnidaria: Hydrozoa). PALAIOS, 7: 96–107.
Stephen D. 2011. Global Diversity of the Stylasteridae (Cnidaria: Hydrozoa: Athecatae). PLoS ONE, 6(7): e21670 doi:10.1371/journal.pone.0021670
Stratford P., (2002) Biology of the red hydrocoral, Errina novaezealandiae, in Doubtful Sound, Fiordland, New Zealand. Unpublished PhD thesis, University of Otago, 362.
Miller K.J., Mundy C.N., Lindsay Chadderton W., (2004) Ecological and genetic evidence of the vul- nerability of shallow-water populations of the stylasterid hydrocoral Errina novaezelandiae in New Zealand’s fiords. Aquatic Conservation Marine and Freshwater Ecosystems, 14: 75–94.


General References

Agassiz, L. 1858. The animals of Millepora are hydroid acalephs and not polyps. American Journal of Science and Arts 26: 140-141

Bax N.N. & Cairns, S.D. 2014. Stylasteridae (Cnidaria; Hydrozoa). pp. 107 - 112 in De Broyer, C., Koubbi, P., Griffiths, H.J., Raymond, B., Udekem d'Acoz, C., Van de Putte, A.P., Danis, B., David, B., Grant, S., Gutt, J., Held, C., Hosie, G., Huettmann, F., Post, A. & Ropert-Coudert, Y. (eds.). Biogeographic Atlas of the Southern Ocean. Cambridge : Scientific Committee on Antarctic Research 498 pp.

Bax NN 2015. Deep Sea Stylasterid Corals in the Antarctic, Sub-Antarctic and Patagonian Benthos: Biogeography, Phylogenetics, Connectivity and Conservation. PhD thesis, Institute for Marine and Antarctic Studies, University of Tasmania. 220pp.

Boschma, H. 1956. Milleporina and Stylasterina. Treatise on invertebarate paleontology, Part F. Geological Society of America pp. 90.

Brooke, S. & Stone, R. 2007. Reproduction of deep-water hydrocorals (Family Stylasteridae) from the Aleutian Islands, Alaska. Science 81: 519–532

Cairns, S. 2010. Stylaster brunneus Boschma, 1970. WoRMS.

Cairns, S.D. 1983b. Antarctic and Sub-Antarctic Stylasterina (Coelenterata: Hydrozoa). Antarctic Research Series 38: 61-164

Cairns, S.D. 1988. New records of Stylasteridae (Cnidaria: Hydrozoa) from Western Australia, including the description of two new species. Records of the Western Australian Museum 14(1): 105–119

Cairns, S.D. 1991b. The marine fauna of New Zealand: Stylasteridae (Cnidaria: Hydroida). Wellington : New Zealand Oceanographic Institute 1-179, pls 1-77.

Cairns, S.D. 1992. Worldwide distribution of the Stylasteridae (Cnidaria: Hydrozoa). Scientia Marina 56: 125-130

Cairns, S.D. 2011. Global diversity of the Stylasteridae (Cnidaria: Hydrozoa: Athecatae). PLoS ONE (Public Library of Science) 6: 13

Cairns, S.D. 2015. Stylasteridae (Cnidaria: Hydrozoa: Anthothecata) of the New Caledonian region. Mémoires du Muséum national d'Histoire naturelle, Paris (N.S.) [1993-2016] 207: 1-362

Cairns, S.D. & MacIntyre, I.G. 1992. Phylogenetic implications of calcium carbonate mineralogy in the Stylasteridae (Cnidaria: Hydrozoa). Palaios 7: 96 – 107

Gray, J.E. in Jukes, J.B. (ed.) 1847. Narrative of the surveying voyage of H.M.S. Fly, commanded by Captain F.P. Blackwood, R.N. in Torres Strait, New Guinea, and other Islands of the Eastern Archipelago, during the years 1842–1846: together with an excursion into the interior of the eastern part of Java. London : T. & W. Boone Vol. 2.

Pica D., Cairns S.D., Puce S. and Newman W.A. 2015. Southern hemisphere deep-water stylasterid corals including a new species, Errina labrosa sp. n. (Cnidaria, Hydrozoa, Stylasteridae), with notes on some symbiotic scalpellids (Cirripedia, Thoracica, Scalpellidae). ZooKeys (1): 472

Post, A.L., Brien, P.E.O., Beaman, R.J., Riddle, M.J. and Santis L.D.E. 2010. Physical controls on deep water coral communities on the George V Land slope, East Antarctica. Marine Ecology 22: 371 - 378


History of changes

Note that this list may be incomplete for dates prior to September 2013.
Published As part of group Action Date Action Type Compiler(s)
05-Aug-2022 CNIDARIA 05-Aug-2022 MODIFIED
03-Sep-2018 HYDROZOA Owen, 1843 23-May-2022 MODIFIED Dr Narissa Bax
05-Aug-2022 13-Aug-2013 MODIFIED
12-Feb-2010 (import)