Giant barrel sponge in North-east Coral Reef, Phu Quoc Island, Vietnam

The giant Barrel Sponge in Phu Quoc is Xestospongia testudinaria, this is a species of barrel sponge in the family Petrosiidae. More commonly known as Giant Barrel Sponges, they have the basic structure of a typical sponge. Known to be one the largest species of sponge, Giant Barrel sponges can grow up to several meters in diameter, their body is made of a reticulation of cells aggregated on a siliceous scaffold composed of small spikes called spicules. Water is taken into the inner chamber of the sponge (known as the spongocoel) through ostia (small pores created by porocytes). Flagellated choanocytes line the inner chamber and help generate water currents through the sponge, it is really good strainer.

Due to the amount of water that Great Barrel Sponges filter throughout their lifespan, they perform an important ecological role.

A cluster of Giant Barrel Sponge at the depth of 5m at North-east Coral Reef, Phu Quoc Island, Vietnam
A cluster of Giant Barrel Sponge at the depth of 5m at North-east Coral Reef, Phu Quoc Island, Vietnam

We found many giant barrel sponge the most at Half-moon Reef, North-east Coral Reef and U-Turn. Especially in North-east Coral Reef, our guests have chances to witness lots of big-sized giant barrel sponge.

A video of a giant barrel sponge recorded in U-Turn coral reef, Phu Quoc Island, Vietnam by our team in April, 2022.


These sponges are sessile filter feeders, with a very important role in the ecosystem. Giant Barrel Sponges filter a tremendous amount of water throughout their lifespan (some living up to 2000 – 10000 years – the longest living animal on the Earth) which increases water clarity, controls algae, and affects coral populations. These sponges also serve as a habitat for many other species such as other invertebrates, benthic fish, bacteria, and cyanobacteria. This Giant Barrel Sponge species is maroon to pink, with the opening of the barrel pale white.

Giant Barrel Sponges play a vital ecological role. It helps improve water clarity, supports reef regeneration, and provides a habitat for other invertebrates, benthic fish, and bacteria. Giant Barrel Sponges a vital role in the food chain and also recycles nutrients for all the reef organisms.



Reproduction occurs through spawning appeared volcanic, whereby localized male sponges release sperms resemble cloud of gametes, and female sponges release eggs into the water column simultaneously in the time frame of approximately one hour. This process takes place at least twice a year, commonly around spring and summer. Fertilization takes place in the water itself, and the larvae are carried away by the water currents. Their growth is highly variable and depends on factors such as competition, nutrition, predation, wave surge, and disease.


Read more about corals in Phu Quoc Island