Lettuce coral (Pectinia lactuca)

Description

Lettuce coral fact file

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

Lettuce coral description

One of the most common Pectinia species ⁽³⁾, Pectinia lactuca typically forms conspicuous colonies of large, thick plates, which may grow to over a metre across and are usually a uniform grey, brown or green in colour ^{(1) (3) (4) (5)}. The colonies are covered in high walls, which may reach several centimetres in height, and elongate, radiating depressions, known as valleys ^{(3) (4) (5) (6)}. As in other corals, the colonies are formed from numerous tiny, anemone-like polyps, which secrete the hard coral skeleton ⁽³⁾. In Pectinia lactuca, the individual skeletons of the polyps (‘corallites’) are quite widely spaced, and have extensions, known as septocostae, which are continuous between them ⁽⁴⁾. Each individual polyp bears long, tubular tentacles, which are widely spaced around a central ‘mouth’. In this species, the tentacles are extended only at night, and then only rarely ^{(3) (5) (6)}.

Also known as

Common lettuce coral.

Lettuce coral biology

Pectinia lactuca is a zooxanthellate coral, meaning that it obtains most of its nutrients from single-celled algae, known as zooxanthellae, which live within its tissues. The zooxanthellae produce energy-rich nutrients through photosynthesis, and in return receive a protected, stable environment, access to sunlight, and waste nutrients from the coral. This relationship limits the coral to living in relatively clear, shallow, warm waters where photosynthesis can take place, but enables it to grow faster and form large reef structures. The coral may also supplement its diet with tiny zooplankton, caught using stinging cells on the tentacles ^{(3) (8)}.

Like other coral colonies, Pectinia lactuca can reproduce asexually by a process known as budding, in which polyps divide into one or more new polyps. It can also reproduce sexually, producing sperm and eggs which are released into the water for external fertilisation. The fertilised eggs develop into larvae, which drift in the water column before settling and developing into polyps ⁽³⁾. At the Great Barrier Reef, Australia, this species has been recorded taking part in ‘mass spawning’ events, in which many coral species spawn over just a few nights of the year, in late spring ⁽⁹⁾. Pectinia lactuca is reported to be hermaphroditic, each polyp producing both eggs and sperm, and the eggs are pink in colour ⁽⁹⁾.

Lettuce coral range

Pectinia lactuca occurs in the Indian Ocean and western Pacific Ocean, from the east coast of Africa, east to Vanuatu and Fiji, north to Japan, and south to Australia ^{(1) (3) (4) (5) (6)}.

Lettuce coral habitat

This species inhabits most reef environments, but particularly lower reef slopes and turbid waters ^{(1) (3) (5)}. It occurs at depths from around 3 to 20 metres, although it is most commonly seen at 12 to 15 metres ^{(1) (7)}.

Lettuce coral status

Classified as Vulnerable (VU) on the IUCN Red List ⁽¹⁾ and listed on Appendix II of CITES ⁽²⁾.

Lettuce coral threats

Although still widespread and common throughout its range, Pectinia lactuca is reported to be particularly susceptible to a number of the threats faced by corals worldwide, including disease and habitat loss, and it is also a common target of the aquarium trade. In addition, the species may be highly susceptible to bleaching, in which a rise in ocean temperatures causes the stressed coral to expel its zooxanthellae, often resulting in death ⁽¹⁾.

In addition to localised threats from fisheries, human development, invasive species, pollution and sedimentation, corals around the world are under severe threat from global climate change, which may lead to more severe, frequent storms, and increased sea temperatures. Rising carbon dioxide levels may also increase ocean acidity, affecting the ability of corals to create the hard coral skeleton. These stresses may also make corals more vulnerable to other factors such as disease ^{(1) (8) (10) (11)}. As a result of these combined threats, around a third of all reef-building corals are now believed to be threatened with extinction ⁽¹⁰⁾, and an estimated 20 percent of the world’s coral reefs have already been destroyed ⁽¹¹⁾.

Lettuce coral conservation

Like all corals, Pectinia lactuca is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES) ⁽²⁾, meaning that international trade in the species should be carefully monitored. This species also occurs in some Marine Protected Areas ⁽¹⁾, including the famous Great Barrier Reef, off the coast of Australia, where various coral research and conservation programmes are underway ⁽¹²⁾. However, enforcement within protected areas is often poor ⁽⁸⁾, and currently less than half a percent of marine habitats receive official protection ⁽¹³⁾.

Specific conservation measures recommended for Pectinia lactuca include further research into its populations, ecology, habitats, and its resilience to various threats ⁽¹⁾. In particular, population surveys are needed to monitor the effects of collection for the aquarium trade, especially in Indonesia, which is the largest exporter ⁽¹⁾. Like many other corals, it would also benefit from the expansion of Marine Protected Areas, reef restoration efforts, collection quotas, and disease and parasite management ^{(1) (8) (11)}. The IUCN recommends that the conservation status of corals be reassessed in ten years or sooner, in light of the predicted threats from climate change and ocean acidification ⁽¹⁾.

Find out more

For more information on corals and their conservation see:

• Veron, J.E.N. (2000) Corals of the World. Australian Institute of Marine Science, Townsville, Australia.
• Reef Check:
  http://www.reefcheck.org/
• The Coral Reef Alliance:
  http://www.coral.org/

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Glossary

Algae

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

Budding

Type of asexual reproduction (reproduction that does not involve the formation of sex cells), in which new individuals develop from the parent organism, forming a swelling similar in appearance to a bud. The ‘bud’ slowly separates from the parent as it grows.

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.

Hermaphroditic

Possessing both male and female sex organs.

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.

Spawning

The production or depositing of large quantities of eggs in water.

Zooplankton

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

References

1. IUCN Red List (May, 2010)
   http://www.iucnredlist.org/
2. CITES (May, 2010)
   http://www.cites.org/
3. Veron, J.E.N. (2000) Corals of the World. Australian Institute of Marine Science, Townsville, Australia.
4. Carpenter, K.E. and Niem, V.H. (1998) FAO Species Identification Guide for Fishery Purposes. The Living Marine Resources of the Western Central Pacific. Volume 1: Seaweeds, Corals, Bivalves and Gastropods. Food and Agriculture Organisation of the United Nations, Rome. Available at:
   ftp://ftp.fao.org/docrep/fao/009/w7191e/w7191e00.pdf
5. Veron, J.E.N. (1993) Corals of Australia and the Indo-Pacific. University of Hawaii Press, Honolulu, Hawaii.
6. Erhardt, H. and Moosleitner, H. (1998) Marine Atlas. Volume 2. Mergus, Melle, Germany.
7. Titlyanov, E.A. and Latypov, Y.Y. (1991) Light-dependence in scleractinian distribution in the sublittoral zone of South China Sea Islands. Coral Reefs, 10: 133-138.
8. 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
9. Babcock, R.C., Bull, G.D., Harrison, P.L., Heyward, A.J., Oliver, J.K., Wallace, C.C. and Willis, B.L. (1986) Synchronous spawnings of 105 scleractinian coral species on the Great Barrier Reef. Marine Biology, 90: 379-394.
10. Carpenter, KE 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
12. UNEP-WCMC: Great Barrier Reef, Queensland, Australia (May, 2010)
    http://www.unep-wcmc.org/medialibrary/2011/06/23/c5f5632e/Great%20Barrier%20Reef.pdf
13. UNEP: Fifty Key Facts about Seas and Oceans (May, 2010)
    http://www.unep.org/wed/2004/Downloads/PDFs/Key_Facts_E.pdf