Sea anemones use their 'shyness' to survive heatwaves

A recent study by researchers at the University of Gothenburg discovered how the humble sea anemone, a creature adorning the rocky coasts of the Atlantic, thrives amidst the challenge of heatwaves.

This revelation not only fascinates but also offers insights into the broader implications of climate change on marine ecosystems.

Enchanting and mysterious

Sea anemones are fascinating marine creatures, part of the phylum Cnidaria, which also includes corals and jellyfish. They are known for their stunning colors and graceful tentacles, which they use to capture prey.

Anemones are sessile, meaning they typically attach themselves to rocks or coral reefs on the ocean floor, though some can move slowly.

They have a simple mouth surrounded by tentacles that contain nematocysts, specialized cells that can sting and immobilize prey such as fish and shrimp.

Impact of heatwaves on sea anemones

Heatwaves, increasingly frequent due to climate change, pose a significant challenge to sea anemones. These marine creatures, accustomed to the stable temperatures of their underwater habitats, are finding it increasingly difficult to cope with the sudden spikes in temperature brought on by heatwaves.

The primary impact of these temperature increases is on the anemones’ metabolic rate, the speed at which they convert nutrients into energy.

In normal conditions, sea anemones maintain a balanced metabolic rate, ensuring they have enough energy for growth, reproduction, and catching prey.

Higher temperatures require more nutrients

However, heatwaves disrupt this balance. The water temperature rises sharply, accelerating the sea anemones’ metabolic processes unnaturally.

This increase in metabolism demands more energy, forcing the anemones to consume more nutrients at a time when their environment may not support such a surge in demand.

The excessive metabolic rate can lead to a host of problems for sea anemones.

Firstly, it strains their physiological systems, potentially leading to increased mortality if the heatwave persists.

Moreover, the demand for more nutrients to fuel their heightened metabolism might not always be met, especially in environments where food is scarce.

This mismatch between energy demand and supply during heatwaves can weaken sea anemones, making them more susceptible to disease and predation.

How sea anemones mastered heatwaves

Despite these challenges, sea anemones are remarkably adaptable, especially with marine heatwaves. When the tide goes out, they can retract their tentacles to conserve moisture and reduce their exposure to the elements.

What’s less obvious is that sea anemones, like many animals, exhibit distinct personality types that influence their behavior.

Some anemones are inherently bold, quick to react to the slightest change in their environment. If they detect a potential meal, they’ll rapidly unfurl their tentacles, ready to capture it.

Other anemones are more cautious, taking their time to assess a situation and responding more slowly. While this “shy” approach might initially seem less efficient for getting food, it becomes an incredible advantage to sea anemones during heatwaves.

Animal personalities and heat waves

Scientists at the University of Gothenburg were fascinated by these personality differences in sea anemones.

They wanted to investigate whether certain personality types gave these creatures a better chance of surviving the increasing heatwaves caused by climate change. They focused their study on a common species called Actinia equina.

“We call them animal personalities. The anemones we studied have two personality traits, bold and shy, and in extreme heatwaves the shy anemones do better,” explains Lynne Sneddon, a zoophysiologist at the University.

Boldness has a cost for sea anemones during heatwaves

The study revealed a striking difference in the physiological response of bold and shy sea anemones to heatwaves. When the water temperature increases, bold anemones experience a significant surge in their metabolic rate.

This means their bodies are working harder, burning through their stored energy at an accelerated pace. To compensate for this heightened energy expenditure, they require a substantial increase in food intake.

During a heatwave, where food resources might become limited, this puts bold sea anemones in a perilous position with heightened risk of starvation.

In contrast, shy sea anemones exhibit a more tempered response to heatwaves. Their metabolism remains relatively stable, allowing them to conserve valuable energy reserves. The energy-saving strategy enables shy anemones to endure the heatwave with a reduced need for food.

This provides a distinct survival advantage by decreasing their reliance on potentially scarce resources during periods of environmental stress.

Animal personalities during climate change

While the study focused on sea anemones, the findings have far-reaching implications. “Heatwaves will become more common in the future and cold-blooded animals may find it difficult to cope,” warns Sneddon.

“If the animals can’t cope, there will be a disruption in the ecosystems, and this could have implications for the whole food web.”

The presence of distinct personalities within a population, like bold and shy anemones, can significantly influence how a species responds to environmental pressures.

Conserving energy is crucial

In this case, shy anemones with their more energy-conserving behavior demonstrate a higher tolerance for heat stress.

This finding suggests that populations with a greater mix of personality types might be more resilient in the face of climate change.

Biodiversity, encompassing both genetic variation and behavioral diversity, can be a powerful tool for adaptation. A species with a wider range of behavioral strategies is better equipped to handle environmental fluctuations.

For example, in a population with a mix of bold and shy anemones, some individuals might be more successful at finding food during normal conditions, while others, like the shy anemones, might be better suited to survive extreme heatwaves.

The power of personality

This research on sea anemones offers a powerful reminder that nature is far more complex than it first appears.

Even seemingly simple creatures demonstrate diverse strategies for survival, and these differences can tip the scales when conditions become harsh.

The next time you admire the vibrant tidepools at your local beach, remember the hidden world of animal personalities unfolding below the surface and the delicate balance of life striving to adapt to a changing planet.

The study is published in the Journal of Experimental Biology.

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