20c stamp: Millepora sp. Fire Coral

90c stamp: Pocillopora verruscosa Cauliflower Coral with Arc-Eye Hawkfish

$1.00 stamp: Porites sp. Lobe Coral with Snubnose Chub

$3.00 stamp in souvenir sheet:  Coral garden with Butterflyfish.

            15 September 1994        20c, 90c, $1.00, $3.00               Mint and CTO            $5.10
                                                                                                     FDC                           $5.60

Technical Details

        Release Date:                    15 September 1994
        Tablet Values:                   20c, 90c, $1.00, $3.00
        Artist:                                Gordon Drummond
        Printer:                              Walsall Security Printers Ltd
        Process:                            Lithography
        Paper:                               CA Watermark
        Stamp Size:                       28.45 x 42.58 mm
        Souvenir Sheet Size:          100 x 71 mm (with $3.00 stamp)
        Perforation Gauge:            14.1 per 20 mm
        Pane Format:                    50 (2 x 25) - 20c, 90c, $1.00
        Mint and CTO:                 $5.10
        First Day Cover:               $5.60

Robert Irving, a member of the Sir Peter Scott Commemorative Expedition to the Pitcairn Islands (1991-1992), supplied the photographic material for this issue.  The Expedition was led by Dr Michael Brooke of Cambridge University.

Previously thought of as plants, it was not until 1726 that the French naturalist Peyssonnel showed that corals were, in fact, an animal form.  Their growth depends on warm water having a minimum temperature of 50°F and it must be clear and free of sediment, sand, slime and mud.  Corals exist ony in relatively shallow water, less than 40 metres (135 feet) beyond which there is unsufficient light for the algae on which they are dependent to achieve photsynthesis.

Jacques-Yves Cousteau, Life and Death in a Coral Sea, defines coral as a

colony of individual coral animals, each of which is known as a polyp.  Each polyp consists of a jelly-like body enclosed in a skeleton of calcium carbonate.  This body - which tends to group with other bodies into solid masses - is generally a hollow digestive system with an opening at the unattached end of the body; this - the 'mouth' of the polyp - is surrounded by tentacles and leads into the gullet.
As these polpys reproduce and attach themselves to the colony those lower down die and new layers are built up on the diead skeletons.  Cousteau explains,
Eventually the skeletons are broken up by the action of waves, by other animals, and in other ways, and when the broken skeletons have been piled in sufficient number, islands and reefs may eventually be formed and vegtation may become established.
In the Pitcairn group of islands, Henderson, Oeno and Ducie were formed in this way; while the latter two remain atolls, subterranean movements caused Henderson to be lifted some sixty feet, giving it the form known as a raised atoll.  Pitcairn's origins differed for it is a volcanic island.

The above information was obtained from:

Andrew C. Campbell  The Coral Seas,  Orbis,  London
Jacques-Yves Cousteau with Philippe Diole  Life and Death in a Coral Sea,  Cassell,  London