When a Tongue Becomes a Parasite’s Throne
Imagine a creature so sinister it hijacks another's body, not to kill but to replace a part of it. Meet the tongue-eating louse (Cymothoa exigua)—a parasitic isopod that enters a fish's mouth, severs its tongue, and positions itself as a grotesque replacement. Though unsettling, this bizarre relationship allows the fish to survive, albeit at a grisly cost.
Thanks to groundbreaking scanning technologies like syGlass® virtual reality, scientists are uncovering fascinating new details about these parasites, from their intricate anatomy to their ancient evolutionary history.
A Modern-Day Encounter with Cutting-Edge Tech
One morning, evolutionary biologist Dr. Kory Evans at Rice University was digitizing fish skeleton scans using syGlass, a state-of-the-art virtual reality platform that renders large image volumes in extraordinary detail. As he examined the skull of a vegetarian wrasse, something caught his attention—a strange, oversized "bug" embedded in the fish's mouth.
Scientist Kory Evans found a tongue-eating louse inside the mouth of a wrasse while looking through scans of fish skeletons one morning. (Photo Courtesy of Dr. Kory Evans)
The tongue-eating louse enters a fish's mouth through its gills, latches onto its tongue, and severs the blood vessels. Then it feeds off that blood until the tongue withers and falls off. (Photo Courtesy of Dr. Kory Evans)
Upon closer inspection through the immersive syGlass visualization, Evans realized this wasn’t a remnant of a last meal. It was a tongue-eating louse. The parasite had severed the blood vessels in the fish’s tongue, feeding off its blood until the organ withered and fell away. The louse then replaced the tongue entirely, functioning as a grisly but operational stand-in.
By leveraging syGlass’ capabilities, Evans could study the parasite in unprecedented detail, rendering a high-resolution 3D image of the isopod's position within the fish's skeletal framework. These insights are reshaping our understanding of the louse’s parasitic relationship and how it integrates with its host.
Fossil Discovery: A Window into the Past
While Evans uses syGlass to peer into the modern-day workings of these parasites, Jason Osborne has brought to light their ancient history. In the Pamunkey River, Virginia, while SCUBA diving in black water swamps, Osborne unearthed a coprolite—fossilized feces—that contained the impression of a new isopod species, Calverteca osbornei, dating back 18 million years. The fossil represents the first known coprolite to preserve such an impression, providing a rare glimpse into the life of ancient parasitic isopods.
Closeup view of the impression of the body of an extinct marine parasitic isopod preserved in fossilized poop. The front of the body is towards the top of the photo. The head is missing from the impression. The coprolite was temporarily coated with a very thin layer of sublimed ammonium chloride to improve contrast on an otherwise very dark-colored fossil. (Photo courtesy of the Calvert Marine Museum)
Using syGlass, researchers could dive deeper into CT scans of the coprolite, virtually exploring the fine details of Calverteca osbornei's anatomy and its fossilized interaction with its host. This virtual reality imaging enables scientists to examine the delicate impression without risking damage to the precious specimen. By integrating data across layers of the fossil, syGlass could reveal even more about the isopod’s morphology, helping to link its traits to modern relatives like the tongue-eating louse.
Implications for Science and Evolution
From Evans's modern fish scans to Osborne’s ancient coprolite discovery, these studies illuminate the ecological impact of parasitic isopods across millions of years. By studying their anatomy and behavior, scientists are piecing together a clearer picture of how these parasites adapted to exploit marine ecosystems.
The application of syGlass in both modern and paleontological contexts highlights the technology’s transformative power in science. "With syGlass, we’re not just looking at specimens—we’re immersing ourselves in their structures," says Evans. "This helps us ask and answer questions we couldn’t even dream of before."
Using syGlass technology, a CT scan reveals the tongue-eating louse (Cymothoa exigua) firmly attached to and replacing the tongue of a wrasse fish in stunning 3D detail.
