In the embrace of anemones. On how clownfish found an ally

In the sea’s depths, where light fades and the unknown begins to reign, a remarkable partnership between clownfish and anemones flourishes. Together they play a survival show that amazes with its finesse and complexity.

Neighbors

Clownfish, also known as anemone fish(Amphiprioninae), are a distinctive group of fish inhabiting the coral reefs of the tropical Indo-Pacific belt. Currently, this group includes 26 recognized species and 2 natural hybrids.

These species inhabit a variety of coral reef environments, from shallow coastal waters to deeper reef zones. Among the most common species are Amphiprion ocellaris (true clownfish) and Amphiprion percula, which are recognizable by their bright orange colors with three white stripes. Their fame was undoubtedly contributed to by Andrew Stanton’s Oscar-winning picture Where’s Nemo.

Anemones(Actiniaria), on the other hand, are marine invertebrates of the coral cluster(Anthozoa), and are characterized by their ability to live in symbiosis with various marine species. These sedentary predators are equipped with parasitoids that are used to defend themselves and acquire food, usually small fish and plankton. Anemones are found worldwide in a wide variety of marine habitats, from shallow coastal waters to the deep oceans.

Symbiosis of clownfish and anemones

The symbiosis of clownfish and anemones is an example of mutualism, which is one of the most characteristic relationships in marine ecosystems. These fish live in direct contact with parasitic anemones, which are a deadly threat to other species.

Mutualism is a form of symbiosis between organisms that is characterized by mutual benefits for both parties. In many cases, this type of cooperation becomes so necessary that it prevents each species from functioning independently in its natural environment.

According to the study, the secret to good neighborliness between clownfish and anemones is mucilaginous substances on their fish skin that prevent the activation of anemone parasitoids. These substances contain special proteins that neutralize the anemones’ parasiticles, allowing clownfish to live safely in their feelers. This process is the result of a long-term evolutionary adaptation that has allowed this unique protective mechanism to evolve. Studies have shown that when young clownfish first come into contact with an anemone, they are exposed to a light sting, which initiates the production of protective mucus. After several such interactions, they become completely immune to their hosts’ parsimony.

Mutually beneficial, or what works for whom

Symbiosis of clownfish with anemones is a subtle dance of benefits. Clownfish gain irreplaceable protection from predators, which significantly reduces their mortality rate. The anemones, with their deadly stingers, become a safe haven. But it’s not just a one-sided relationship – the clownfish’s movements improve water circulation around the anemones, which increases oxygen availability and helps remove food residues. In return, the anemones grow faster and are healthier. The presence of clownfish also deters potential threats, such as fish feeding on polyps, making the relationship full of mutual benefits.

Climate change a threat to neighborhoods

Climate change is a process that, like a silent thief, sneaks into marine ecosystems, leaving a trail of destruction in its wake. One of the most visual evidences of its impact is the process of fading of corals and anemones, whose colorful bodies are losing their vivid hues. This phenomenon is due to the loss of symbiotic algae, which live in the tissues of these animals and are crucial to their nutrition and intense color.

The fading of anemones also has direct consequences for clownfish, which rely on these organisms for shelter, breeding sites and food sources. A study conducted in the Gulf of Eilat in the Red Sea between 1997 and 2015 showed that the number of two species of anemones declined by 86 percent, and the population of clownfish living in symbiosis with them decreased by 74 percent.

Although the situation may seem bleak, there are also reasons for optimism. Scientists have discovered that anemones along the coast of Australia, despite losing their symbiotic algae and fading, are still able to survive. Thanks to an effective parasitic venom that enables them to hunt, these marine organisms show remarkable resilience. This ability to survive in harsh conditions is good news for both the anemones themselves and the clownfish that find refuge in their parasitic arms.

Photo. main: Sebastian Pena Lambarri/Unsplash