Cluster anemones are one of the first things that are visible when someone dives into the Mediterranean Sea. It is one of the most fascinating and magnificent corals to see in the area.

Cluster anemones can be seen on rocks or sponges inside the dark sea caves and gorges where it clusters in close agglomerations that look like yellow and orange carpets.

A new study published in Scientific Reports by researchers from the University of Bologna found proof that these corals known as cluster anemones belong to two species.

Two Species of Cluster Anemones

The study identified two species of Parazoanthus axinellae, which differ in color, size, and preferred substratum. The researchers took samples of the cluster anemones from 11 different locations across the Mediterranean Sea to compare their DNA. From Banyuls-Sur-Mer in France to Rovinj in Croatia, then through Portofino, Olbia, Gallipoli, and Chioggia in Italy.

Federica Constantini, a professor at the University of Bologna's Department of Biology, Geology and Environmental Science and one of the authors of the study, explained that their team found evidence of marked genetic isolation between the two morphotypes of P. axinellae.

But said that further investigation is needed to confirm their hypothesis that the cluster anomalies are indeed two species. He noted that the data on species composition and marine populations' connectivity patterns is crucial in devising effective methods on protecting biodiversity in the Mediterranean Sea.

The two types of cluster anemones are the Slender and Stocky type. The Slender type can be found across the entire Mediterranean Sea which is characterized by its light-yellow color, an elongated trunk, and it has long thin tentacles. It mainly lives on the sponges of Axinella.

While the Stocky type found in the north-western Mediterranean Sea and is characterized by its deep orange color, shorter and thicker trunk, and tentacles. The Stocky type lives on the rocky substra.

They examined the two species and found that the SLender type is genetically closer to two coral species that also live on sponges, namely the Parazoanthus anguicomus and Parazoanthus capensis, but they are found in the Caribbean.

Meanwhile, the Stocky type has genetic similarities with coral species that live in the shallow waters in the Pacific Ocean, namely the Parazoanthus elongatus and Parazoanthus juanfernandezii. It is also related to one species, called Parazoanthus aliceae, that can be found deep beneath the Eastern Atlantic Ocean.

The researchers noted that none of these species have colonized sponges as the anemones live mainly on rocky substra.

Read Also: Stony Corals Are About to Go Extinct


High Mortality Rate of Anemones

Despite discovering that anemones have two species, the anemones still have high mortality rates these past few years especially in areas in the north-western Mediterranean due to high temperatures that are unusually long.

According to experts, this phenomenon is caused by the increasing number of cyanobacteria in the area that weaken the corals and sometimes lead to death.

Professor Costantini said that the existence of these complex species may make conservation efforts of cluster anemones more difficult. Since these species present different characteristics, they may also have different resistance to stress from climate change which means different management strategies are needed to address this issue.

Lastly, the researchers said that the diversity observed in the Parazoanthidae family should be taken into consideration because it may also be found among other species that live in a delicate and fragile coralligenous area in the Mediterranean Sea.

Read More: Probiotic Bacteria Like Those Found in Yoghurt Can Boost Coral Health in the Great Barrier Reef: Study


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