Distinguishing features

A soft coral with a thick encrusting morphology. The colony surface is raised, and there is considerable variation between species in terms of the morphology of the lobes and ridges. Some species have digitate projections, others have broken ridges, and others have long complex ridges which extend across much of the colony surface. There are two types of polyps; the longer autozooids which are extensible, and the smaller siphonozooids which stay flush with the colony surface. The colonies have a distinct "hairy" appearance when auotozooids are extended. Colonies may be up to 4-5m in diameter.

The genera Sarcophyton and Lobophytum are in need of revision. Recent molecular analysis of 92 specimens from the Indo-Pacific showed 19 species of Lobophytum and 16 species of Sarcophyton. "Phylogenetic analysis showed three distinct clades. One clade included only morphologically typical Sarcophyton species with a stalk distinct from the polypary, poorly formed club-shaped sclerites in the colony surface, and large spindles in the interior of the stalk. A second clade included only morphologically typical Lobophytum colonies with lobes and ridges on the colony surface, poorly formed clubs in the colony surface, and interior sclerites consisting of oval forms with regular girdles of ornamental warts. The third distinct clade included a mix of Sarcophyton and Lobophytum sp. nominal species with intermediate morphologies. Most of the species in this mixed clade had a polypary that was not distinct from the stalk, and the sclerites in the colony surface were clubs with well-defined heads. Within the Sarcophyton clade, specimens identified as Sarcophyton sp. glaucum belonged to six very distinct genetic sub-clades, suggesting that this morphologically heterogeneous species is actually a cryptic species complex" McFadden et. al (2006).

Size

Synonyms

Distribution

Distribution and habitat preferences

Digitate specimens most commonly seen in sheltered back reef and lagoonal habitats. Large encrusting specimens often found on windward reef flats and crests.

Can be found in most reef habitats around Lizard Island.

Behaviour

Lobophytum sp. is well known for its high concentrations of toxic organic compounds including terpenes and cembranes, which deter predators and also inhibit settlement and competition from other benthic organisms. The egg cowrie (Ovula ovum) and several butterflyfish species (Chaetodon melannotus) are known to feed on this coral however.

The coral can reproduce in a number of ways, including fragmentation, polyp brooding and external spawning. At Lizard Island, the species is gonochoric, with separate male and female colonies in approximately equal numbers. Broadcast spawning takes place after the full moon in November during the reef-wide mass spawning event, however small numbers of gametes are also released after full moons from August to February.

Growth is slow, about 5mm per year, and large stands over 10m could well be more than a century old.

Web resources

References