Acropora

Taxonavigation Kingdom: Animalia Sub Kingdom: Eumetazoa Super Phylum: Radiata Phylum: Cnidaria Class: Anthozoa Sub Class: Hexacorallia Order: Scleractinia Family: Acroporidae Genus: Acropora Group: Acropora (Group 1) - Acropora (Group 2) - Acropora (Group 3) - Acropora (Group 4) - Acropora (Group 5) - Acropora (Group 6) - Acropora (Group 7) - Acropora (Group 8) - Acropora (Group 9) - Acropora (Group 10) - Acropora (Group 11) - Acropora (Group 12) - Acropora (Group 13) - Acropora (Group 14) - Acropora (Group 15) - Acropora (Group 16) - Acropora (Group 17) - Acropora (Group 18) - Acropora (Group 19) - Acropora (Group 20) - Acropora (Group 21) - Acropora (Group 22) - Acropora (Group 23) - Acropora (Group 24) - Acropora (Group 25) - Acropora (Group 26) - Acropora (Group 27) - Acropora (Group 28) - Acropora (Group 29) - Acropora (Group 30) - Acropora (Group 31) - Acropora (Group 32) - Acropora (Group 33) - Acropora (Group 34) - Acropora (Group 35) - Acropora (Group 36) - Acropora (Group 37) - Acropora (Group 38)

Introduction

The genus Acropora has more species than any other genus of coral. The exact number of species is unknown and there is much debate as to which species are valid or not. For example, Wallace (1999) recognises 113 species, whereas Veron (2000) recognises over 300 nominal species.

Characteristics

Acropora colonies are unique among stony corals in possessing two distinct types of corallites and polyps. Each branch can have one (subgenus Acropora), or more (subgenus Isopora) axial corallites and many radial corallites. The axial corallites are the growing tips of the branches and radial corallites arise from behind the axial corallites.

Captive Requirements

Acropora have the same general requirements as any zooxanthellate coral:

• sufficient lighting,
• sufficient water movement,
• calcium at around 420 mg/L ± 30 mg/L, and
• alkalinity at around 2.8 meq/L ± 0.3 meq/L

Additionally, most species do better with undetectable nitrate and phosphate. As to how much light and water movement is sufficient, that will depend very much on the species.

Some species are found in shallow water and so need a fair amount of light and can tolerate a lot of light. Some are found in deeper water (as deep as 70m) and don't need as much light, although these are less likely to be available in the hobby. Providing a "medium" amount of light will allow you to keep most species. "Medium" amount of light can be provided as follows:

• 150W metal halide over a 45cm high tank
• 250W metal halide over a 60cm high tank
• 400W metal halide over a 90cm high tank

You could go for slightly lower light using T5 or even NO lamps, but you would need a few lamps and they'd need to be on for 12 to 16 hours per day. It is worth noting that Acropora species can acclimate very well to different amounts of light. You don't have to provide them an exact amount of light.

For flow, there is also quite a bit of variation. Acropora with long thin branches generally come from areas of low flow. Acropora with short thick branches come from areas of high flow. In a tank, I would class low flow as around 10 time the tank volume in water movement per hour. For example, on a 200L tank, 2000 litres per hour of in tank circulation is 10X. High flow would be 30-40X. If you settle on around 20X you should be able to keep most species but will need to place them in the tank appropriately.

Classification

The Acropora genus can be split into the following groups based on the structural characteristics of the colonies and corallites:

• Group 1: forming solid plates and columns with no distinictive axial corallites.
• Group 2: thick tubular branches and immersed radial corallites.
• Group 3: irregular branchs and prominent radial corallites.
• Group 4: buffalohorn-like.
• Group 5: elkhorn-like.
• Group 6: large staghorn-like.
• Group 7: large encrusting or horizontally branches with rasp-like radial corallites.
• Group 8: large horizontally branching with upturned branch ends.
• Group 9: interlocking basal branches and sharp edged radial corallites.
• Group 10: interlocking basal branches and rounded radial corallites.
• Group 11: conspicuous secondary branches and smoothed edged corallites.
• Group 12: small staghorn-like.
• Group 13: middle sized branches and sharp edged radial corallites.
• Group 14: middle sized branchs and irregular radial corallites.
• Group 15: irregular middle sized interlocking branches forming compact thickets.
• Group 16: fine interlocking branches forming compact thickets.
• Group 17: flat branches and radial corallites on branching sides.
• Group 18: forming plates and tables with robust horizontal branches.
• Group 19: forming tables with fine horizontal branches.
• Group 20: forming digitate clumps with cylindrical branches and distinctive radial corallites.
• Group 21: forming digitate clumps with finger-like branches.
• Group 22: forming digitate clumps with small branchlets.
• Group 23: forming irrgular clumps with very dominant axial corallites.
• Group 24: forming digitate clumps with spiny corallites.
• Group 25: forming corymbose cushions with thickets with scale-like radial corallites.
• Group 26: branching with scale-like radial corallites.
• Group 27: forming corybose clumps with thin branchlets and appressed radial corallites.
• Group 28: forming corybose clumps with diverging horizontal branches and small radial corallites.
• Group 29: forming corybose clumps with thin branchlets and radial corallites with flaring lips.
• Group 30: forming corybose clumps with short compact branchlets and variable radial corallites.
• Group 31: forming corybose clumps or plates with elongated tubular axial corallites.
• Group 32: forming corybose clumps with conspicuous rounded corallites.
• Group 33: forming bushes with irregular smooth edged radial corallites.
• Group 34: forming bushes with sharp edged radial corallites.
• Group 35: forming bushes with appressed radial corallites.
• Group 36: forming thickets with fine upright banches and conspicuous radial corallites.
• Group 37: forming tangles with delicate branches and fine radial corallites.
• Group 38: forming bottlebrush colonies.

Grouping of the genus can also be / is based on sub genera: Acropora (Acropora) - Acropora (Isopora).

Gallery

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  A. robusta
  Group: Group 7

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  A. solitaryensis
  Group: Group 9

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  A. abrolhosensis
  Group: Group 12

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  A. tortuosa
  Group: Group 14

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  A. millepora
  Group: Group 25

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  A. selago
  Group: Group 29

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  A. loripes
  Group: Group 32

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  A. echinata
  Group: Group 38

Miscellaneous Images

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  Purple colour variation.

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  Multi-coloured variation.

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  Close up of polyps.

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  Showing laminar or table growth form.

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  Zoanthus sp. growing through Acropora sp.

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  Hydnophora pilosa attacking an Acropora sp. with mesenteric filaments.

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  Mesenteric filaments

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  Dead colony, showing white "cobwebs" that appear while tissue is decomposing.

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  Dead colony, showing white "cobwebs" that appear while tissue is decomposing.

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Resources

• Propagation of Small-Polyped Stony Corals by Greg Hiller - Reefkeeping Magazine
• Changing Acropora Colours - Reefs.org
• An Aquarist's Experiences with a Species of Acropora Parasites by Greg Hiller - Advanced Aquarist's Online Magazine
• Need Help! Coral ID?: Part 1 - Taxonomy of Stony Corals by Eric Borneman - Reefkeeping Magazine
• Changing Acropora Colours by Eric Borneman, Andy Hipkiss and Minh Nguyen - Reefs.org
• Acropora Growth Movie Page
• Marine Life Profile For: Staghorn or Acropora Coral - Waikiki Aquarium
• wikipedia:Acropora
• Acropora Overdose - pictures of Acropora exposed at low tide.
• An Introductory Guide to the Acropora or Staghorn Corals of the World's Coral Reefs, Acropora identification program and an introductory guide to the Acropora corals - coralsee.org