Dykning med Boblekoraller

Koh Lantas Marineliv | Euphyllidae

Der findes flere arter af boblekoraller i det indiske Stillehavsområde, og nogle af dem kan vi finde her på dykkerstederne omkring Koh Lanta.

Boblekoraller kan forveksles med blødkoraller, men de har et hårdt, stenet skelet lige under overfladen. 'Boblerne' kaldes vesikler, som blæses op med væske om dagen for at fange sollys til fotosyntese. Om natten tømmes vesiklerne for luft og trækkes tilbage, og fødetentaklerne kommer frem.

Individer af samme art kan se lidt forskellige ud, afhængigt af oppustningen af vesiklerne (boblerne) og det miljø, de befinder sig i. De er dog ret nemme at identificere, da hver af de arter, der findes på vores dykkersteder, er ret forskellige fra de andre og har forskellige vesikler og skeletvækst.

2 arter fundet på denne side:

Grape Coral (Plerogyra sinuosa)
Hammer Coral (Euphyllia ancora)

Grape Coral

(Plerogyra sinuosa)

Grape Corals are easy to identify and are very abundant at the dive sites and reefs around Koh Lanta. This species forms small to very large colonies in both shallow, and deeper water.

Plerogyra sinuosa @ Koh Bida

During the day, Grape Coral colonies show inflated, grape-sized, bubble-like, vesicles which are almost transparent and are filled with the symbiotic algae zooxanthellae.

During the day, these vesicles are exposed to sunlight, producing oxygen and food for the coral polyps.

Hawksbill Turtle's favourite food @ Koh Rok

Grape Coral vesicles are inflated or deflated depending on the amount of light available and colonies can look quite different depending on the level of inflation. At night, Grape Coral vesicles are deflated and retracted, with the feeding tentacles then extended to catch plankton.

The skeleton of Grape Coral colonies forms inverted cones of meandroid winding ribs and valleys which can be seen when the vesicles are retracted, or when part of the colony is damaged/broken.

Hammer Coral

(Euphyllia ancora)

Hammer Coral has puffy tubular polyps with T-shaped tips which are extended both day and night to varying lengths, but cannot be retracted, making this an easily identified coral species. The polyp tips contain zooxanthellae and vary in colour from a light cream through to orange, green and brown.

Euphyllia ancora colonies @ Koh Haa

Hammer Coral polyps are arranged in meandroid rows, usually in colonies up to a meter across.

At some dive sites such as Koh Haa and Koh Rok, multiple colonies form together to cover many meters of substrate. Hammer Coral polyps can give a nasty sting if touched by humans.

Euphyllia ancora @ Koh Haa

As with other bubble coral species, Hawksbill Turtles love to eat Hammer Coral polyps.

Euphyllia ancora @ Koh Haa