+66 (0)89 050 3009

Massive Sponges


Scallops Fanworms

Sponges of the Petrosiidae family are often huge, vase-shaped or volcano-shaped sponges, sometimes encrusting, bulbous, and less commonly branching growth forms. Around Koh Lanta, the most obvious family member is the Giant Barrel Sponge, which is found on all of our coral reefs.

The texture of these sponges is usually stony and brittle due to most species having more spicules (very small sharp-pointed spines) than spongin, which is the fibrous substance found in the skeleton of many sponges.

The outer layer of Petrosiidae sponges are covered in these small sharp pointed spines, which form a pattern of interlacing lines resembling a net. This covering creates a crust which gives the surface of the sponge a smooth appearance.

1 species found on this page.

Giant Barrel Sponge

Xestospongia muta

Giant Barrel Sponge (Xestospongia muta) @ Koh Haa

Giant Barrel Sponge @ Koh Haa

The Giant Barrel Sponge can grow well over 1 m in diameter and is typically brownish-red to brownish-grey in shallow water, becoming more pinkish with depth. This species has a hard, stony texture and can grow for hundreds, even thousands of years.

This species has a varied form, often a very large barrel-like shape, slightly cone-shaped at the top. Shapes of individual sponges within colonies can vary widely from short to tall, thin to wide, with the surface being smooth, rough or rugged.

The Giant Barrel Sponge lives symbiotically with cyanobacterial, bacteria that obtain their energy through photosynthesis, which gives colour to the sponge. This is a similar relationship to that of coral polyps living with symbiotic algae.

The Giant Barrel Sponge undergoes sporadic bleaching events which do not cause sponge death, and from which the sponge recovers. This is part of the normal life cycle of this sponge and demonstrates that the sponge does not depend on the symbiotic bacteria to exist. Bleaching events occur more often with depth, and the reason for these events is not yet fully understood.

Diving with Massive Sponges

Spot Massive Sponges on one of our daily Koh Lanta diving trips. Or if you prefer to keep your adventure on the surface, you can also book one of our Koh Lanta snorkeling trips.

Join our speedboat dive trips to some of Koh Lanta's best dive sites and enjoy small groups, great personal service and short journey times on our fast boats.

Not yet a diver? Discover a whole new world with Discover Scuba Diving on Koh Lanta, or get certified with the Open Water Diver course on Koh Lanta.

If you're already a certified diver, take your diving knowledge and skills to the next level with the Advanced Open Water Diver course on Lanta.

Book online to save 10% on diving trips and scuba courses here on Koh Lanta.

Find Out More

More Marine Life References and Further Information


Diving, Snorkeling & PADI Courses

Send us an email and we'll get back to you as soon as possible.

  • Please let us know:

    • when will you arrive on Koh Lanta?
    • your previous dive experience?
    • which diving activities you are interesed in?
  • If you're already here on Lanta, you can also call us on +66 (0)89 050 3009