Knotted Fan Coral (Red Spongy Coral) – Phu Quoc Coral Species

Knotted Fan Coral Melithaea ochracea in the Coral Jungle Reef, Phu Quoc Island, Vietnam

Melithaea ochracea is a species of colonial soft coral in the family Melithaeidae, commonly known as knotted fan coral. It grows in tree-like fans on coral reefs in the South China Sea or the East Sea, Vietnam. It is used in the jewellery industry under the name red spongy coral. Along with Sea Whip and branching soft-coral, they are collectively known as Gorgonian coral.

Knotted Fan Coral at the Coral Jungle Reef, the healthiest coral reef in Phu Quoc Island, Vietnam. Photo: OnBird Phu Quoc

Colonies of Melithaea ochracea are arborescent and usually grow to about 20 cm (8 in) long although much larger specimens can be found. They grow in one plane and have a branching, fan-shaped structure. The main skeletal stalk and branches are jointed, with swellings at the larger joints. The internodes are composed of hard, calcareous material while the joints are flexible and made of a horny material. The skeleton is covered by a flexible membrane, the mesoglea, which contains minute calcareous spicules or sclerites. The identity of these is important for distinguishing between different closely related species. In Melithaea ochracea, they include capstans, double discs, disc-spindles and unilaterally spinose spindles, plain spindles, clubs and anthocodial sclerites. Three sides of the branches are densely covered in calyces, dome shaped perforated structures from which the polyps protrude. Colonies vary in colour but tend to be shades of yellow, orange, red and white, sometimes with contrasting colours for the calyces and polyps. It is an azooxanthellate coral and does not contain symbiotic unicellular algae in its tissues. In Singapore, it sometimes grows close to the low tide mark at depths of under 3 metres (9.8 ft) where colonies grow larger than deeper water specimens and mostly have yellow branches and red calyces. At greater depths, down to 15 metres (49 ft), the colonies are smaller and have different colour combinations.


Where to see Knotted Fan Corals in Phu Quoc Island?

The Coral Jungle Reef and the North-east Coral Reef are the places where you can spot Knotted Fan Corals in Phu Quoc, especially in the Coral Jungle Reef, the healthiest coral reef in Phu Quoc Island, Vietnam. At the depth of 5 m we can see this Knotted Fan Coral at the Coral Jungle Reef clearly.