Elliptical star coral (Favia speciosa)

Elliptical star coral fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Elliptical star coral description

One of the most common species in the Faviidae family, particularly at high latitudes ^{(1) (4)}, Favia speciosa typically forms domed colonies that vary in colour from pale grey or green to brown ^{(4) (5)}. Its colonies may also sometimes be encrusting, adhering closely to the substrate ^{(2) (5)}. As in all corals, the colonies of Favia speciosa are composed of numerous, anemone-like animals known as polyps, which have a sac-like body and a central ‘mouth’, surrounded by tentacles ^{(4) (6)}. In this species, the inside and outside of the polyps may be different colours ^{(4) (5) (7) (8)}, often being green on the inside and brown on the outside ⁽⁷⁾. As in other Favia species, the tentacles of Favia speciosa taper towards the end ⁽⁴⁾.

Like most other corals, Favia speciosa secretes a hard skeleton, with the skeleton of an individual polyp being known as a ‘corallite’ ⁽⁴⁾. In Favia speciosa, the corallites are circular in cross-section and have numerous fine, regular inward projections, or septa. Each corallite measures up to 1.2 centimetres in diameter ⁽⁵⁾ and typically has its own separate walls, which are not shared with those of its neighbours ^{(2) (4) (5) (8)}.

When this species grows in shallow water, the corallites are usually quite closely packed, but in deeper water they tend to be more widely spaced ^{(4) (5)}, with each polyp growing larger in diameter ⁽⁷⁾. The polyps of Favia speciosa have also been known to grow larger in areas with greater sedimentation ⁽⁹⁾.

Favia speciosa is very similar to the closely related Favia pallida, and the two species can be difficult to distinguish on outward appearance ^{(5) (8)}. However, internally the corallites of Favia speciosa have thinner, more numerous and more regularly arranged septa ⁽⁵⁾.

Synonyms

Astraea speciosa.

Size

Average colony size: 25 - 40 cm ⁽²⁾

Elliptical star coral biology

Favia speciosa is a zooxanthellate coral, meaning that it obtains most of its nutrients from microscopic algae, known as zooxanthellae, which live within its tissues. The zooxanthellae provide the coral with nutrients through photosynthesis, and in return receive a safe, stable environment in which to live. However, this close association restricts corals such as Favia speciosa to living in relatively clear, warm, shallow waters where light levels are high enough to allow photosynthesis to take place ^{(4) (6)}.

As well as receiving nutrients in this way, Favia speciosa is also able to feed on tiny zooplankton, which it catches using stinging cells on its tentacles. The tentacles of this species are only extended for feeding at night, being retracted during the day ⁽⁴⁾. The larger polyp size of this species in deeper or more sediment-filled waters may potentially allow it to obtain more of its energy requirements from zooplankton in conditions where photosynthesis is more challenging ^{(7) (9)}.

Little specific information is available on the reproductive behaviour of Favia speciosa. However, this species is known to be able to reproduce asexually by division of the polyps to produce new ‘daughter’ polyps. Corals are also able to reproduce sexually, usually by releasing large numbers of sperm and eggs into the water column. The fertilised eggs develop into larvae, which eventually settle onto the substrate and develop into polyps ⁽⁴⁾.

Elliptical star coral range

Favia speciosa is widespread throughout the western and central Pacific Ocean and in the Indian Ocean, including the Arabian Gulf and Red Sea ^{(1) (4) (5)}.

Elliptical star coral habitat

An inhabitant of all types of coral reef environment ^{(1) (4) (5)}, Favia speciosa can be found at depths of up to 20 metres ^{(1) (7)}.

Elliptical star coral status

Favia speciosa is classified as Least Concern (LC) on the IUCN Red List ⁽¹⁾ and is listed on Appendix II of CITES ⁽³⁾.

Elliptical star coral threats

Favia speciosa is widespread and common over its extensive range, and is not currently considered to be at risk of extinction. However, like most corals this species faces a variety of threats, and its population is likely to be in decline ⁽¹⁾.

One of the major threats to corals is climate change, which may lead to increased sea temperatures that can cause corals to expel their zooxanthellae, often resulting in death. This process, known as ‘bleaching’, also leaves corals weakened and more vulnerable to disease, which is becoming a serious threat to coral reefs worldwide. In addition, climate change may cause more frequent, damaging storms, while rising carbon dioxide levels in the ocean are increasing ocean acidity and affecting the ability of corals to produce their hard skeletons ^{(1) (6) (10) (11)}.

Favia speciosa is also likely to be affected by a number of more localised threats to reefs, including sedimentation, pollution, invasive species, destructive fishing practices, and other impacts from increasing human development ^{(1) (6) (10) (11)}. Like many corals, this species may be harvested for the aquarium trade in some areas ⁽¹⁾.

Fortunately, its widespread distribution and abundant population mean that Favia speciosa may be more resilient than other corals to these threats ⁽¹⁾.

Elliptical star coral conservation

Like all corals, Favia speciosa is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), meaning that any international trade in this species should be carefully monitored and controlled ⁽³⁾. In addition, parts of this species’ range fall within Marine Protected Areas, which may offer it some protection ⁽¹⁾, although enforcement within these is often poor ⁽⁶⁾.

Recommended conservation measures for Favia speciosa and other coral species include further research and monitoring, the expansion of protected areas, efforts to combat coral disease, and measures to tackle global climate change ^{(1) (6) (11)}. The harvest of Favia speciosa for the aquarium trade should also be more closely monitored and regulated. Techniques for growing corals artificially or storing their eggs and sperm may also become important for coral conservation in the future ⁽¹⁾.

The predicted effects of climate change and ocean acidification on coral reefs mean that it will be important to reassess the conservation status of Favia speciosa in the near future, to ensure it has not become endangered ⁽¹⁾.

Find out more

Find out more about corals and their conservation:

• Corals of the World Online:
  http://coral.aims.gov.au/
• Reef Check:
  http://www.reefcheck.org/
• The Coral Reef Alliance:
  http://www.coral.org/

Authentication

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

Glossary

Algae

Simple plants that lack roots, stems and leaves but contain the green pigment chlorophyll. Most occur in marine and freshwater habitats.

Asexual reproduction

Reproduction that does not involve the formation of sex cells (‘gametes’). In many species, asexual reproduction can occur by existing cells splitting into two, or part of the organism breaking away and developing into a separate individual. Some animals, including vertebrates, can also develop from unfertilised eggs; this process, known as parthenogenesis, gives rise to offspring that are genetically identical to the parent.

Colony

A group of organisms living together. Individuals in the group are not physiologically connected and may not be related, such as a colony of birds. Another meaning refers to organisms, such as bryozoans, which are composed of numerous genetically identical modules (also referred to as zooids or ‘individuals’), which are produced by budding and remain physiologically connected.

Fertilisation

The fusion of gametes (male and female reproductive cells) to produce an embryo, which grows into a new individual.

Larvae

Stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.

Photosynthesis

Metabolic process characteristic of plants in which carbon dioxide is broken down, using energy from sunlight absorbed by the green pigment chlorophyll. Organic compounds are made and oxygen is given off as a by-product.

Polyp

Typically sedentary soft-bodied component of cnidaria, a group of simple aquatic animals including the sea anemones, corals and jellyfish. A polyp comprises a trunk that is fixed at the base, and a mouth that is placed at the opposite end of the trunk and is surrounded by tentacles.

Septa

In a coral, radial elements that project inwards from the corallite wall (the skeletal wall of an individual coral polyp).

Zooplankton

Tiny aquatic animals that drift with currents or swim weakly in water.

References

1. IUCN Red List (December, 2012)
   http://www.iucnredlist.org/
2. Scott, P.J.B. (1984) The Corals of Hong Kong. Hong Kong University Press, Hong Kong.
3. CITES (December, 2012)
   http://www.cites.org/
4. Veron, J.E.N. (2000) Corals of the World. Australian Institute of Marine Science, Townsville, Australia.
5. Dai, C.F. and Horng, S. (2009) Scleractinia Fauna of Taiwan. II. The Robust Group. National Taiwan University Press, Taipei, Taiwan.
6. Miththapala, S. (2008) Coral Reefs. Coastal Ecosystems Series (Volume 1). Ecosystems and Livelihoods Group Asia, IUCN, Colombo, Sri Lanka. Available at:
   http://data.iucn.org/dbtw-wpd/edocs/2008-012.pdf
7. Caras, T., Bachar, A. and Pasternak, Z. (2008) Morphological variation in the oral disc of the scleractinian coral Favia speciosa (Dana) at Indonesia. Computational Biology and Chemistry, 32(5): 345-348.
8. Riegl, B.M. and Purkis, S.J. (Eds.) (2012) Coral Reefs of the Gulf: Adaptation to Climatic Extremes. Springer Science+Business Media B.V., Dordrecht, Netherlands.
9. Todd, P.A., Sanderson, P.G. and Chou, L.M. (2001) Morphological variation in the polyps of the scleractinian coral Favia speciosa (Dana) around Singapore. Hydrobiologia, 444: 227-235.
10. Carpenter, K.E. et al. (2008) One-third of reef-building corals face elevated extinction risk from climate change and local impacts. Science, 321: 560-563.
11. Wilkinson, C. (2008) Status of Coral Reefs of the World: 2008. Global Coral Reef Monitoring Network and Reef and Rainforest Research Center, Townsville, Australia. Available at:
    http://www.gcrmn.org/status2008.aspx