Tag: zoantharians

Corals’ Boldest Cousins: UH Scientists Discover Marine Creatures Bending the Laws of Evolution

A new Frontiers of Biogeography study shows zoantharian hexacorals defy biogeographic norms with narrow genetic differences across the Atlantic and Indo-Pacific.

Guest blog post by Dr. Maria “Duda” Santos and Maria Frostic

In the realm of marine biogeography, there is a widely held scientific principle: the Atlantic and Indo-Pacific oceans are worlds apart. If you dive in Brazil and then in Okinawa, you expect to see entirely different groups of fish and coral. But according to a new global study published today in Frontiers of Biogeography, one group of colorful hexacorals, anemone-like creatures—known as zoantharians—is breaking all the rules.

The study, led by Dr. Maria “Duda” Santos of the UH Mānoa Hawaiʻi Institute of Marine Biology (HIMB) ToBo Lab and the University of the Ryukyus, began with a moment of “déjà vu” underwater. 

Diver in Malaysia looking at a coral reef
Underwater view in a Malaysian coral reef with Duda searching for zoantharian species. Photo by Sam Webster.

“During my first dive in Okinawa, I was surrounded by a multitude of species I had never seen in my homeland of Brazil. But then I saw the zoantharians. They looked exactly like the ones back home—the same colors, shapes, and sizes. It was striking.”

shares Dr. Santos

While the Indo-Pacific typically hosts ten times the species diversity of the Atlantic for most reef animals, this research found that the genetic and morphological divergence between oceans for these creatures is surprisingly narrow.

The Secrets of the Ultimate Travelers

Zoantharians from different parts of the ocean that surprisingly show narrow evolution despite the distance
Sibling zoantharians from the Indo-Pacific (A) and the Atlantic (B) oceans. Images by Dr. Maria “Duda” Santos.

The researchers suggest that zoantharians may be the ultimate oceanic travelers. Their secret likely lies in high dispersal via an “epic” larval phase, where young zoantharians can survive in open water for over 100 days, paired with an ability to “raft” across ocean basins by hitchhiking on floating objects.

Furthermore, an unusually slow evolutionary rate appears to keep distant populations looking and acting like siblings, even after millions of years of separation by continental barriers.

This discovery has major implications for the future of our oceans. As climate change stresses traditional stony corals, zoantharians are increasingly moving in to fill the void. 

“In habitats impacted by stress, some zoantharian species can outcompete stony corals. We are seeing ‘phase shifts‘ where reefs once dominated by corals are being taken over by zoantharians. Understanding how they spread helps us forecast what the reefs of the future will look like.”

explains Dr. Santos

A Global Atlas for a Changing Ocean

This landmark study represents a massive international effort, uniting a team from Hawai’i, Okinawa, Russia, Brazil, Hong Kong, Taiwan, and Indonesia. By combining DNA data and records from Mexico to the Philippines, the team has provided the first-ever global “atlas” for a group of animals that has remained in the shadows of their more famous coral cousins for decades. This map of the past and present provides a vital baseline for monitoring how marine life will navigate a warming world.

Original source

Santos, M.E.A., Kise, H., Fourreau, C.J.L., Kiriukhin, B., Kitahara, M.V., Baker, D.M., Toonen, R.J., Liu, P.J., Chang, A., Tu, T.-H., Widiastuti, Agustini, K.M.P., Bowen, B.W. and Reimer, J.D. (2026). Global biogeography of zoantharians indicates a weak genetic differentiation between the Atlantic and Indo-Pacific oceans, and distinct communities in tropical and temperate provinces. Frontiers of Biogeography, 19. doi: https://doi.org/10.21425/fob.19.174247

Three new species of zoantharians described from coral reefs across the Indo-Pacific

One of them was named after the president of Palau, Tommy Remengesau, in honour of his and the nation’s support to the authors and marine conservation

Three new species of zoantharians were discovered by researchers from the University of the Ryukyus and Kagoshima University, Japan, and the Palau International Coral Reef Center. Despite not being previously known, all three species were found widely across the Indo-Pacific, with at least two species found in the Red Sea, the Maldives, Palau, and southern Japan.

Zoantharians, or colonial anemones, include species popular in the pet trade such as Zoanthus or Palythoa, but the new species are all much more cryptic, living in marine caves, cracks, or at depths below most recreational SCUBA diving (>20 m). The research was published December 29, 2017, in the open-access journal ZooKeys.

The three new species belong to the genus Antipathozoanthus, which contains species that only live on top of black coral colonies. However, surprisingly, one of the new species does not live on black corals, but instead in narrow cracks in coral reefs.

obscurus“We think that the new species, Antipathozoanthus obscurus, has evolved away from needing to be on top of black corals to take advantage of the available space in coral reef cracks”, said lead researcher Hiroki Kise.

“This is yet another example of how much diversity is right underneath our noses, but we still know nothing about it.”

Coral reefs, which are widely threatened by rising temperatures from global warming, are generally believed to harbour very high numbers of species, including yet many undescribed or unknown species.

Amongst the other two new species is Antipathozoanthus remengesaui, named after the current president of Palau, Tommy Remengesau.

“Much of our work was based in Palau”, said senior author Dr. James Reimer, “and we wished to acknowledge the fantastic support we have received from the nation. Palau is considered at the forefront of marine conservation, and much of this is thanks to President Remengesau’s vision.”

While the new discoveries shed more light on our understanding of coral reef biodiversity, this work is far from done. In fact, the researchers themselves estimate they still have up to ten more zoantharian species to describe from the waters of Palau and Okinawa.

“Marine diversity of coral reefs is amazing, with new surprises all the time”, said Kise, “and biodiversity scientists still have a lot more work to do.”

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Original source:

Kise H, Fujii T, Masucci GD, Biondi P, Reimer JD (2017) Three new species and the molecular phylogeny of Antipathozoanthus from the Indo-Pacific Ocean (Anthozoa, Hexacorallia, Zoantharia). ZooKeys 725: 97-122. https://doi.org/10.3897/zookeys.725.21006