A sea slug smaller than a grain of rice was identified in the coastal waters of Keelung, in the north of Taiwan, revealing the existence of marine species still unknown to science. The translucent organism, covered in distinctive black and yellow markings, was given the scientific name Thecacera sesama by researchers at National Taiwan Ocean University, National Museum of Natural Science and National Taipei University of Education. The creature measures less than 3 millimeters in length.
The species name refers to the similarity of aloe vera to sesame seeds. “Taiwanese divers call it ‘sesame’ in Chinese and it is as small as a sesame seed, hence the name,” explained the research team responsible for cataloging the new nudibranch.
Descoberta casual during recreational diving
The identification of Thecacera sesama occurred unexpectedly while Ho-Yeung Chan, the study’s lead author, was still a graduate student. Durante a summer 2019 recreational dive in Taiwan’s northern waters, Chan spotted the small organism for the first time. Ele did not suspect that it was a species unknown to the scientific community.
The research breakthrough came only after Chan contacted a sea slug expert online. Conforme reported by the team, “he never realized that Thecacera sesama was a new species until he consulted the sea slug expert ‘Hsini Lin teacher’ at Facebook.” Esse contact via social media led to the correct identification of the creature and the beginning of the formal scientific description process.
Condições adverse weather limits research
Studying the new species faced significant challenges due to the unpredictable weather patterns of Taiwan’s north coast. The region experiences regular typhoons during the summer, while the winter monsoon season brings big waves and colder waters. Water temperatures can drop below 16 degrees Celsius, making diving conditions difficult for most of the year.
Pesquisadores revealed that they are only able to conduct studies on nudibranchs for approximately 4 months per year. Essa restricted time window imposes severe limitations on submarine expeditions in the region. The team of scientists also noted that locating such tiny marine animals often depends more on luck than systematic planning, considering the creatures’ small size and limited search window.
Strongly marked seasonal weather patterns drastically reduce opportunities to conduct underwater surveys. Apesar Despite these difficulties, the discovery was documented and formally described by the international scientific community.
Simple living Estilo focused on basic activities
The researchers observed that T. sesama apparently dedicates its existence to just 4 main activities: feeding, foraging, mating and egg laying. The species was found living on bryozoans, small aquatic invertebrates commonly known as “moss animals.”
Curiosamente, the very species of bryozoan that functions as a habitat for the b-slug may have been previously unknown to science. Essa possibility further expands the discovery’s implications for understanding regional marine biodiversity. The organisms maintain a clear dependency relationship, with the sea slug using the bryozoan as a food source and living environment.
Ecological Papel of nudibranchs in the marine food chain
Apesar Due to their small size, nudibranchs play important roles in marine ecosystems. “Nudibranchs are one of the main players in the marine food web,” explained the research team. “They are extremely colorful and can be seen in coral reef ecosystems. Porém, many nudibranchs are very small and extremely difficult to see in the water with the naked eye.”
The small size of these organisms acts as a natural hiding factor, making their detection a complex task even for experienced divers. Sua vibrant coloration remains visible only when observed closely or with the aid of appropriate optical equipment.
Potencial for future discoveries in marine biodiversity
Researchers believe the discovery of Thecacera sesama may represent just a glimpse of Taiwan’s hidden marine biodiversity. Dada the prevalence of tiny and easily overlooked oceanic species, scientists suspect that many others still await identification and cataloguing.
The waters around Taiwan, particularly in the regions of Keelung and surrounding areas, have hydrodynamic and ecological characteristics that favor the existence of diverse marine life. The pattern of serendipitous discoveries during recreational activities suggests that systematic scientific expeditions could uncover multiple previously unknown species.
Publicação and scientific recognition
The study describing Thecacera sesama was published in the open access journal ZooKeys on May 11, 2026. Formal scientific documentation follows international protocols for zoological nomenclature and description of new species. Pesquisadores from multiple Taiwanese institutions collaborated on the research, reinforcing the importance of collective initiatives to understand biodiversity.
The discovery exemplifies how collaborative research, often facilitated by digital platforms and scientific social networks, can accelerate the identification and cataloging of new species. The find also demonstrates the importance of documenting casual observations by recreational divers, who often occupy the same habitats where rare species reside:
- Espécie discovered during recreational diving in 2019
- Nome scientific Thecacera sesama related to the appearance of sesame
- Tamanho less than 3 millimeters in length
- Vive in bryozoans on the northern coasts of Taiwan
- Pesquisa possible only 4 months a year due to weather conditions
- Official Publicação in scientific magazine in May 2026