‘Hammer’-head creature found in forest that survived Korean War. See new species
Researchers in the Republic of Korea, or South Korea, have discovered two unusual invertebrate species through the first study of its kind in more than 100 years.
Between 2020 and 2022, researchers Ji-Hun Song and Fernando Carbayo scoured the forests day and night in search of land planarians — odd worms defined by their “hammer-shaped, half-moon, or sickle-shaped” heads, according to a study published Aug. 26 in the Journal of Zoological Systematics and Evolutionary Research.
In the daytime, the pair encountered the planarians, often called hammerhead worms, hiding under rotting logs or rocks. At night, they made their way to the surface of the soil, according to the study.
DNA analysis has confirmed that among the flatworm specimens collected by Song and Carbayo were two new species, according to the study.
Bipalium gwangneungensis and Novibipalium koreanum were both described as having “cloak-shaped” heads and “elongate” bodies, according to researchers.
Novibipalium koreanum has distinctive dark stripes running the length of its body and can measure up to 2 inches long, the study said.
Bipalium gwangneungensis is slightly smaller, with a maximum length of about an inch and a half, and a body that is uniformly beige.
Some of the most significant differences between these two species and other related species pertain to the size, positioning, and orientation of their reproductive organs, according to the study.
Impacts of war and occupation
Researchers said the Korean Peninsula has suffered from “large-scale overexploitation and deforestation,” with less than half of 1% remaining in a “fully natural state” like forests or alpine meadows.
“Land-use changes in the 20th century, particularly during the Japanese occupation and Korean War, likely led to the decline or disappearance of many soil-dwelling invertebrates, including land planarians,” researchers said.
The small remaining patches of forests have acted as “important refuges” for land planarians, according to the study.
Researchers said their work underscores the need for additional study on soil-dwelling species and the need to protect the “vulnerable habitats” in which they live.
This story was originally published August 28, 2025 at 6:03 PM with the headline "‘Hammer’-head creature found in forest that survived Korean War. See new species."
