Okinawa, Japan – April 2025 — A team of scientists from the Okinawa Institute of Science and Technology (OIST) has discovered two previously undocumented species of tapeworms (cestodes) in the wild oval squid (Sepioteuthis lessoniana), marking a significant advancement in marine parasitology.
The research, conducted by the Physics and Biology Unit at OIST, identified the parasitic worms in the stomachs and intestinal tracts of wild-caught squids. According to Dr. Mehmet Arif Zoral, all detected cestodes were in the larval stage, indicating that oval squids may act as intermediate hosts in the parasites’ life cycles.
Meet the Newly Discovered Tapeworm Species
One of the two tapeworms has been officially classified as a new species, named Nybelinia enterika. The name derives from the Greek word enter (intestine) and ika, the Japanese term for squid. The second species belongs to the genus Phoreiobothrium, although its exact species remains unidentified.
“No cestodes were observed outside the squid’s gastrointestinal tract,” said Dr. Zoral, suggesting that the parasites may be restricted to the gut lining, possibly due to the intestinal wall acting as a natural barrier.
Genetic Sequencing and Diagnostic Potential
In a peer-reviewed study recently published in the Journal of Invertebrate Pathology, researchers not only described the morphological features of these parasites but also analyzed their mitochondrial genomes (mitogenomes) and several nuclear genomic regions.
“These genetic sequences could become valuable biomarkers for early detection of parasitic infections,” explained Dr. Zdenek Lajbner. The larvae are extremely small—Nybelinia enterika measures just 1 millimeter in length, while the Phoreiobothrium species is about 0.5 millimeters, making molecular diagnostics essential.
Implications for Human Health and Aquaculture Safety
Although the potential health risk to humans remains uncertain, Dr. Lucia Zifcakova warns that enzymes secreted by these parasites to break down squid tissue are known to trigger allergic reactions in some people.
Importantly, the study also confirmed that farm-raised (aquaculture) squid showed no signs of infection, highlighting a possible safety advantage in commercial aquaculture practices.
📚 Reference:
Zoral, M.A., et al. (2025). Infection of two cestode larvae, Nybelinia enterika sp. nov. and Phoreiobothrium sp. in oval squid Sepioteuthis lessoniana species complex. Journal of Invertebrate Pathology. DOI: 10.1016/j.jip.2025.108329
🏢 Provided by:
Okinawa Institute of Science and Technology Graduate University (OIST)