Diving with Merulinidae

Lanta Marine Life | Merulinidae

Merulinidae are a family of stony corals which create large colonies and are reef-building corals. The corals are seen everywhere when diving around Koh Lanta.

Members of this family are common around Koh Lanta and have a wide range of colony shapes. Corallites are often directly next to each other, packed tightly, sharing coralite walls and are often highly fused.

Colonies can be massive (genus Hydnopora), encrusting (genus Hydnopora), Foliaceous (genus Merulina), or branched (genus Hydnopora, Paraclavarina, Scapophyllia).

2 species found on this page:

Hard Brain Coral (Platygyra lamellina)
Moon Coral (Dipsastraea lizardensis)

Hard Brain Coral

(Platygyra lamellina)

The Hard Brain Coral is usually found in shallower areas of the reef and can form very large mounds, sometimes with swollen nodes, but can also form plates. The coralites form meandering valleys, containing several polyps and forming thick walls. The coralite septa (teeth) are uniform, neatly arranged and rounded.

Platygyra lamellina @ Koh Haa

The Hard Brain Coral is often a shade of brown due to the septa (teeth), with the valleys being greenish or grey.

The coralite walls can be one to one and a half times the thickness of the valleys between them.

Hard Brain Coral @ Koh Haa

The Hard Brain Coral can be distinguished from the similar Platygyra daedalea by the thickness of the corallite walls and the more rounded septa.

Moon Coral

(Dipsastraea lizardensis)

Moon Coral (sometimes called Knob Coral) colonies can be massive, often over one metre in diameter, they can be rounded, or flat.

The uniformly spaced coralites are conical with thick walls, and the septa are widely spaced and a little irregular.

Dipsastraea lizardensis @ Koh Haa

Moon Coral has a wide variety of colours, sometimes marked with smears or spots, and the calices (surrounding the mouth) are often pale.

Moon Coral @ Koh Haa