A new species of marine worm was discovered off the Pacific coast of Costa Rica, specifically at Playa Naranjo in Guanacaste. The discovery surprised researchers due to the animal’s striking appearance, whose coloration resembles a jaguar’s coat.

The species was named Sthenelais onca, and its discovery was confirmed through the BioMar-ACG project, a scientific initiative involving the Center for Marine Science and Limnology Research (CIMAR) at the University of Costa Rica.

A discovery that began in 2016

The official description of this new species was recently published in the international scientific journal ZooKeys, in a study by researchers Jeffrey A. Sibaja-Cordero and Waiomi Miranda-García.

The first encounter with this unusual worm took place in February 2016, during fieldwork conducted at Playa Naranjo. On that occasion, the scientists collected four specimens hidden in damp sand. However, it wasn’t until a second expedition in May 2024 that they were able to obtain more specimens and complete the formal description of the species.

Inspired by the jaguar’s appearance

According to the researchers, the worm immediately caught their attention due to its size, anatomy, and color pattern. It features orange, gray, and cream tones that resemble the spots of the jaguar (Panthera onca), one of the most iconic felines in the Americas.

The worm features orange, gray, and cream tones that resemble a jaguar’s fur; it was given this name precisely because of that resemblance and because it is a predator within the marine ecosystem.

That visual resemblance, combined with its predatory behavior within the marine ecosystem, inspired the name Sthenelais onca.

The discovery once again demonstrates Costa Rica’s biological richness and the importance of continuing to explore and study the country’s marine ecosystems, where species still unknown to science remain.

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