How Does Coral Protect Itself
Table of Contents
How Does Coral Protect Itself Against Disease and Other Natural Stressors?
While it might be hard to think of any natural defense mechanisms that corals could use to defend themselves against human-caused stressors such as overfishing, tourism and the direct fragmentation and selling of coral formations, it’s important to also ask: how does coral protect itself against natural problems like elevated heat, acidification and disease? These three stressors are seen by most scientists as the most important to take note of, especially with the recent bleaching events caused by global warming.
How Coral Defends Itself Against Disease
New research into the defensive mechanisms of coral polyps have revealed that they have a far more complex means of dealing with disease and bacteria than was previously believed. Several studies revealed that corals have similar defenses to surface-dwelling plants and animals when faced with the threat of bacteria or fungal infections. Corals use an enzyme known as chitinase, which has the main purpose of attacking the cell wall of a fungus and rendering the attacking fungi harmless. When coral polyps are adversely affected through cuts and abrasions, they release the enzyme into the affected area.
Ocean Acidification and Coral Protection
Ocean acidification, caused by the rise in CO2 levels beneath the surface of the ocean, is one of the major causes of coral bleaching. Researchers have discovered that some varieties of corals actually have an in-built mechanism that protects them against acidification. By studying corals found on the Great Barrier Reef, scientists found they have a reserve of calcifying fluid that they can use to regulate the pH of the water surrounding them. This means of regulating water conditions actually allows the coral to grow at a stable rate, despite the fact that water acidification might severely affect other species in their immediate environment.
Can Corals Learn from Past Experiences?
Whether global warming is caused primarily by human involvement or not, its effects are very real, and they influence coral reef growth and survival to a great extent. However, recent studies show that corals actually have the ability to learn from past experiences, especially when going through severely warming climates. Australian researchers recently observed that sheltered coral formations actually experienced more severe bleaching events after being exposed to El Nino events, than corals residing close to neighboring islands that were hit by temperature fluctuations more often. This shows coral populations can actually evolve almost in real time to become more resilient to temperature changes, adapting to their surroundings at a rate that was not previously thought possible. While we might still ask, “how does coral protect itself against more serious problems that we are causing today?”, understanding the details behind coral polyps’ natural defenses could help scientists devise better ways to protect coral reefs before they disappear completely and become extinct.
How Does Coral Protect Itself?
Corals, those vibrant architects of the ocean’s shallow waters, are more than just underwater ornaments. They are dynamic organisms engaged in a constant battle for survival. Despite their serene and static appearance, corals have developed a myriad of strategies to protect themselves from a range of threats, including predators, disease, and environmental stresses. This article delves into the fascinating world of coral defense mechanisms, shedding light on the science behind their survival tactics.
Mechanical Defenses: Coral’s Physical Armor
The Skeleton’s Shield
At the heart of a coral’s defense is its skeleton, scientifically known as the calcium carbonate structure. This rigid exoskeleton provides not only support but also acts as a formidable barrier against physical threats. The exoskeleton’s intricate design, with its nooks and crannies, can deter many would-be predators, making it difficult for them to navigate or find a comfortable spot to latch onto.
Mucous Membrane: The Sticky Guard
Corals secrete a protective mucous layer that serves multiple defense functions. This mucus acts like a biological sticky trap, ensnaring sediment and tiny organisms that may pose a threat. Furthermore, it’s packed with antibacterial compounds that ward off pathogens. This slimy coating is continuously renewed, ensuring that the coral remains shielded against microbial invaders and the buildup of harmful sediments.
Chemical Warfare: Coral’s Invisible Armor
Toxic Compounds: The Chemical Deterrent
Corals are not just passive dwellers of the sea; they engage in active chemical warfare to fend off predators and competitors. Many species produce toxic compounds, such as terpenoids, which can be harmful or distasteful to fish and other marine creatures. These chemical defenses are particularly crucial for corals in nutrient-rich waters, where competition for space and light is fierce.
Allelopathy: The Battle for Space
In the crowded reef environment, space is a precious commodity. Corals use a strategy known as allelopathy, releasing chemicals into the surrounding water to inhibit the growth of neighboring coral species. This chemical battle ensures that a coral can maintain its territory and access to vital sunlight, preventing overgrowth by more aggressive species.
Behavioral Adaptations: Coral’s Dynamic Defense
Symbiotic Relationships: Allies in the Reef
Corals have formed symbiotic relationships with various marine organisms, which play a significant role in their defense strategies. For instance, the partnership with zooxanthellae, a type of algae, is well-known for its role in coral nutrition through photosynthesis. However, this alliance also offers protection, as the vibrant colors provided by the algae can act as camouflage, blending the coral with its surroundings and making it less conspicuous to predators.
Feeding Strategies: Nighttime Warriors
Many coral species adopt a nocturnal lifestyle to protect themselves. By extending their polyps only at night to feed, they reduce the risk of daytime predators. This behavior not only helps in evading threats but also in maximizing feeding efficiency, as many planktonic organisms are more abundant under the cover of darkness.
Conclusion
Corals are far from being passive underwater entities; they are equipped with a sophisticated arsenal of defense mechanisms that ensure their survival in the competitive and sometimes hostile marine environment. From the physical barrier of their calcium carbonate skeletons to the complex chemical and behavioral strategies, corals continuously adapt to mitigate threats and sustain their crucial role in the ocean’s ecosystems.
FAQs on Coral Defense Mechanisms
1. How do corals use their skeletons for protection?
Corals’ skeletons, made of calcium carbonate, act as a physical barrier against predators and environmental damage. The complex structure of the skeleton can also deter potential threats by making it difficult for them to physically harm the coral.
2. What role does the mucous layer play in coral defense?
The mucous layer secreted by corals traps sediments and small organisms, preventing them from settling on the coral. It also contains antibacterial compounds that protect the coral from pathogens.
3. How do corals engage in chemical warfare?
Corals produce toxic compounds and other chemicals to deter predators and prevent overgrowth by competing species. This chemical warfare is a crucial part of their defense strategy, especially in nutrient-rich environments where competition is intense.
4. Can corals form alliances for protection?
Yes, corals form symbiotic relationships with various marine organisms, such as zooxanthellae algae, which can offer camouflage and additional protection against predators.
5. Why do some corals feed only at night?
Feeding at night allows corals to minimize exposure to daytime predators. This nocturnal behavior helps them evade threats while taking advantage of the increased availability of planktonic food sources after dark.
