Cymothoa exigua (Tongue-Eating Louse): Biology, Geographic Distribution, Life Cycle, and Host–Parasite Interactions

Abstract

Background: Cymothoa exigua (tongue-eating louse) is one of the most marine parasites within the family Cymothoidae because of its unique ability to replace the tongue of fish host. This topic also has scientific significance due to its environmental and health impacts.
Objectives: This review summarizes the biology, taxonomy, geographic distribution, life cycle, environmental specialization, host–parasite interactions of Cymothoa exigua, research gaps and future perspectives.
Methods: A narrative literature review conducted using published articles from scientific databases among them PubMed, Web of Science, Google Scholar, and World Register of Marine Species (WoRMS). Peer-reviewed studies related to Cymothoa exigua were selected, reviewed and synthesized according to the objectives of this review.
Results: The literature indicates that Cymothoa exigua is distributed in the eastern Pacific Ocean, ther are also a few reports confirming its presence in other regions around the world. This parasite has a complex life cycle includes (protandrous hermaphroditism) and establishes itself within the oral cavity of fish. Tongue-replacement strategy of this parasite effects on host feeding, respiration, and reproductive performance. Significant gaps were also revealed concerning molecular taxonomy, host immune responses, and the effects of environmental changes on parasite distribution.
Conclusion: Cymothoa exigua is considered unique model for understanding coevolution between host and parasite and the mechanism of parasitism in the marine environment particularly in fish. Research that integrates ecological and microbiological aspects is important for understanding the biology of this parasite and for support fisheries management and conservation of marine biodiversity.