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Home › Sea Life Facts › Coral Formations › Bubble Corals (P. sinuosa)

Interesting Facts about Bubble Corals

[Phylum: Cnidaria] [Class: Hexacorallia] [Order: Scleractinia (stony corals)] [Family: Plerogyridae]

Bubble coral (scientific name Plerogyra sinuosa) is a fascinating gelatinous organism found in some tropical marine environments.

This segment contains fun facts and information about bubble corals and why this bubbly species of stony corals is essential for some fish families and other reef-dwelling creatures.

Plerogyra Sinuosa Habitats and Distribution

The common name used for this particular species of coral comes from its bubble-like appearance.

Even though most people call it "bubble coral", other common names for their colonies include:

• Bladder coral
• Grape coral
• Pearl coral

So, where do most bubble corals live? In fact, the geographic range of Plerogyra sinuosa is limited to habitats that offer the right kind of conditions for their growth and survival.

You will find them in various tropical marine environments, especially the Indo-Pacific region. The preferred habitat also includes the sheltered regions of:

• Great Barrier Reef
• Japan (Okinawa)
• Southeast Asia (e.g. Indonesia, Malaysia, and The Philippines)
• The Red Sea
• Western Indian Ocean (e.g. Madagascar)
• Western Pacific islands

Bubble corals prefer to live in calm, sheltered areas with moderate to low water movements. Hence, they thrive better in some caves, lagoons, and beneath subterranean overhangs.

Here's the thing:

They are typically found at depths ranging from three (3) to thirty five (35) metres (115 feet) below the surface.

Even so, unlike some shallow water corals (e.g. elkhorn coral), it's more common to find them in deeper parts of coral reef formations - due to the lower light intensity.

Bubble Coral Appearance and Characteristics

The coral gets its common name from the bubble-shaped polyps which can be over two (2) centimetres (1 inch) in diameter.

These soft fleshy polyps inflate during the daytime to help them maximise light absorption for the symbiotic algae (zooxanthellae). However, they get stressed if there is too much sunlight.

The grape-like bubbles vary in colour from translucent white to shades of green or blue - caused by the symbiotic algae (zooxanthellae) inside their tissues.

But wait - there's more:

They need gentle water movement that brings in nutrients and removes their waste products. Thus, they cannot tolerate strong currents because they can damage their delicate reef-polyps.

Pro Tip: Bubble corals are a part of coral reef ecosystems and contribute to its biodiversity. While they may not dominate reef structures, they play an essential role in providing habitat and food for small reef organisms, especially crabs and shrimps.

What Do Bubble Corals Eat?

Bubble corals (Plerogyra sinuosa) are opportunistic feeders. In other words, they can get nutrients from multiple sources.

Photosynthesis (Primary Source)

Being a typical zooxanthellate means bubble corals harbor zooxanthellae (symbiotic algae) within their tissues.

The algae performs photosynthesis, and converts sunlight into sugars and other nutrients. It then shares them with the coral colony.

The collection of carbon and nitrogen provides almost all the coral's energy needs (up to 90%) for metabolism and growth.

Bubble Coral and Plankton

At night, when the coral's bubble-like polyps deflate, it extends its long, stinging tentacles to capture planktonic organisms and other small prey from the water.

As a consequence of that, the diet of these heterotrophic feeders (e.g. actively capturing food) can also include:

• Phytoplankton (microscopic algae)
• Zooplankton (tiny animals such as copepods and larval crustaceans)

Thus, bubble corals are also able to absorb dissolved organic material and small particles from the water column to supplement their nutrition.

How Does Bubble Coral Reproduce?

In fact, Plerogyra sinuosa is a typical hermaphroditic species. This means each individual has male and female reproductive organs.

Put another way, it can reproduce sexually through the release of gametes and asexually through fragmentation.

Threats and Predators

Due to its striking appearance, bubble coral is a popular choice among marine aquarium enthusiasts. Even so, it requires a lot of care, an appropriate amount of lighting, stable water conditions, and a supply of meaty food, such as:

• Brine shrimp
• Finely chopped seafood (e.g., fish or squid)
• Liquid coral foods (rich in amino acids)
• Mysis shrimp
• Rotifers (wheel animalcules)

Like many species of corals, Plerogyra sinuosa is sensitive to changes in water temperature, pollution, and ocean acidification.

Furthermore, a process known as coral bleaching - caused by stress factors like rising sea temperatures - can also harm the species.

The preference for specific environmental conditions makes bubble corals particularly vulnerable to certain threats like habitat destruction, climate change, and pollution. So, conservation efforts are vital to preserving their natural habitats.

Pro Tip: The IUCN Red List of Threatened Species last assessed bubble coral phylum Cnidaria in 2023. They cited almost all of this hard coral species as being of "Least Concern" (LC).

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