Last Updated on 02/13/2024

Tubastrea is a genus of stony corals belonging to the family Dendrophyllidae. They are also called sun corals or cup corals due to their aspect when having their tentacles extended and retracted respectively.

The sun corals are large polyp stony corals, meaning that they produce a calcium carbonate exoskeleton. However, they do not forma coral reefs, but just small colonies. Sun corals are branched and the tubular structures hold the large and fleshy polyps. The corallites are well developed and teethed. Tubastrea polyps resemble a sun during the night when they have their tentacles extended for feeding. During the day, these are retracted and so the polyps and visible corallites take the shape of a cup. Colors range from bright orange to dark green. Colonies can grow to 15 centimeters in diameter or even more.

Most sun corals are specific to the Indo-Pacific region. These can be found from the Red Sea to the Indian Ocean, the East China Sea, Ryukyu Islands and the East, North and West Coast of Australia. However, one species, T. coccinea, was first documented in the Caribbean region. This species is invasive. Other species have been introduced to the Atlantic Ocean, the Caribbean Sea, Golf of Mexico as well as Africa, Brazil and New Zealand. Sun corals live in deep waters, caves, with some species such as T. coccinea colonizing even artificial structures. Some colonies have even been found in bright shallow waters from 0 to 3 meters.

Notable species include T. coccinea, the orange cup coral, T. aurea, the yellow sun coral, T. faulkneri, the orange sun coral and T. micantha, the black sun coral. T. coccinea is an invasive species colonizing waters where it is introduced even by accidents. It can also grow and thrive on artificial surfaces, from ship wrecks to cement, steel or granite. T. micantha has smaller tentacles and colors range from dark green to even black in the center area, thus earning its name black sun coral.

Tubastrea species are azooxanthellate, meaning they do not rely on tiny dinoflagellate for food. Because they do not need the sun for photosynthesis, these corals can also thrive in dark areas and at deeper depths than most other corals. Sun corals are heterotrophic so they have to catch their food. They do this by extending their tentacles at night and stinging small zooplankton organisms that draw too close. Digestion takes place in the polyp’s sack. The polyps can also get suspended organic matter from the water column.

Sun coral reproduction can be sexual and asexual. Sexual reproduction is performed during mass spawning events which can happen in spring, summer or even winter depending on the species as well as climate. The resulting free-swimming larvae called planulae reattach to the substrate. New colonies are rarely formed more than 1 meter away from the parent colonies. Asexual reproduction can also be performed through budding, where the original colony forms runners which can grow up to 10 centimeters per year. These Tubastrea runners have polyps at the end that will cement itself on the substrate and form a new colony.

The Fascinating World of Tubastrea: An Exploration into Coral Ecology

Tubastrea, often referred to as sun corals, are a captivating and important part of our marine ecosystems. This article aims to delve into various aspects of Tubastrea, shedding light on their unique characteristics, ecological role, and challenges they face. Whether you’re a marine enthusiast or just curious about the natural world, this exploration of Tubastrea is sure to provide valuable insights.

Anatomy and Physiology of Tubastrea

The Structure of Tubastrea Polyps

Tubastrea, scientifically known as Tubastraea spp., are renowned for their distinct polyps. These polyps, the basic unit of coral anatomy, play a pivotal role in the survival and growth of Tubastrea. Each polyp is equipped with tentacles used for feeding, which are usually extended at night. Unlike many other coral species, Tubastrea do not rely on symbiotic algae (zooxanthellae) for nutrition. Instead, their survival hinges on capturing plankton and other small organisms from the surrounding water.

Tubastrea’s Reproductive Mechanisms

The reproduction of Tubastrea is a fascinating aspect of their biology. These corals employ both asexual and sexual reproduction methods. Asexual reproduction occurs through a process known as budding, where new polyps develop directly from the parent polyp. In sexual reproduction, Tubastrea release eggs and sperm into the water column, leading to external fertilization. The resulting larvae, known as planulae, eventually settle on a suitable substrate to form new colonies. Understanding these reproductive strategies is crucial for coral restoration efforts.

Habitat and Distribution

Tubastrea’s Preferred Marine Environments

Tubastrea corals are primarily found in warm, tropical waters around the world. They thrive in a variety of marine environments, from shallow reefs to deeper waters. These corals prefer locations with moderate to strong water currents, which aid in food delivery. Their ability to survive in lower light conditions, unlike many coral species, allows them to colonize different types of habitats, including under ledges or inside caves.

Geographic Distribution and Spread of Tubastrea

The geographic spread of Tubastrea is both natural and influenced by human activities. Originally native to the Indo-Pacific region, these corals have expanded their range to other parts of the world, including the Atlantic. This expansion, often facilitated by human activities such as shipping, has led to Tubastrea being classified as an invasive species in some regions. Their proliferation in non-native habitats can have significant impacts on local marine ecosystems.

Interaction with Marine Ecosystems

Role of Tubastrea in Coral Reef Ecology

Tubastrea corals play a unique role in coral reef ecosystems. As non-photosynthetic corals, they provide habitat and refuge for a variety of marine organisms. Their structure offers shelter and breeding grounds for small fish and invertebrates. However, their lack of symbiotic algae means they do not contribute significantly to reef building, a role typically played by other coral species.

Tubastrea and Biodiversity

The presence of Tubastrea can have both positive and negative impacts on local biodiversity. In their native habitats, these corals add to the structural complexity and diversity of the reef ecosystem. However, in non-native regions, they can outcompete local coral species for space and resources, potentially reducing biodiversity. Understanding these dynamics is essential for managing and conserving coral reef ecosystems.

Challenges and Threats to Tubastrea

Environmental Threats to Tubastrea

Tubastrea, like many coral species, faces numerous environmental threats. Climate change, resulting in rising sea temperatures and ocean acidification, poses a significant risk. These changes can stress coral polyps, leading to decreased growth rates and increased susceptibility to diseases. Additionally, pollution and habitat destruction also threaten their survival.

Human Impact on Tubastrea Populations

Human activities have a profound impact on Tubastrea populations. Overfishing and destructive fishing practices can damage coral reefs, while coastal development and pollution can degrade their habitats. Furthermore, the introduction of Tubastrea to non-native regions through shipping and other means poses ecological challenges, necessitating careful management and monitoring.

FAQs About Tubastrea

1. What distinguishes Tubastrea from other coral species? Tubastrea, or sun corals, differ from many coral species in that they do not contain symbiotic algae (zooxanthellae) for photosynthesis. Instead, they rely solely on capturing plankton and other small organisms for nutrition.
2. How do Tubastrea corals reproduce? Tubastrea employ both asexual and sexual reproduction methods. Asexual reproduction occurs through budding, where new polyps develop from the parent. In sexual reproduction, they release eggs and sperm into the water, leading to external fertilization and the formation of planulae larvae.
3. Can Tubastrea be found in aquariums? Yes, Tubastrea are popular in the aquarium trade due to their vibrant colors and unique feeding habits. However, they require specific care, including targeted feeding, as they do not photosynthesize.
4. What is the impact of Tubastrea on local ecosystems when they become invasive? In non-native habitats, Tubastrea can outcompete local coral species for space and resources, potentially leading to reduced biodiversity and altered marine ecosystems.
5. Are Tubastrea corals affected by climate change? Yes, Tubastrea, like other corals, are impacted by climate change. Rising sea temperatures and ocean acidification can stress these corals, leading to decreased growth and increased susceptibility to diseases.