The Eel: Origins, Diversity, and Its Role in Ecosystems and Human Society

Eels are one of the most mysterious and fascinating creatures in the aquatic world. With their snake-like bodies and elusive behaviors, eels have intrigued scientists, fishermen, and cultures for centuries. These fish are not only biologically unique but also play a crucial role in both natural ecosystems and human economies. This article explores where eels originate, how many species exist, and the many benefits they offer to the environment and to people around the globe.

Where Did Eels Originate?

Eels belong to the order Anguilliformes, which includes around 800 known species of elongated fish. Fossil records suggest that eels have existed for over 100 million years, dating back to the late Cretaceous period. Although their exact evolutionary path is still being studied, eels are believed to have evolved from ancient bony fish that adapted to a more serpentine body shape for navigating through narrow crevices in reef and freshwater environments.

Among eels, the most well-known group is the freshwater eels of the genus Anguilla, which includes the European eel (Anguilla anguilla), the American eel (Anguilla rostrata), and the Japanese eel (Anguilla japonica). These species are notable for their unique life cycle that involves catadromous migration—they live in freshwater rivers and lakes but migrate thousands of kilometers to the ocean to spawn. For instance, both the European and American eels are believed to spawn in the Sargasso Sea in the Atlantic Ocean, although spawning has never been directly observed.

How Many Species of Eel Are There on Earth?

There are approximately 800 recognized species of eels globally, categorized under the order Anguilliformes. This order includes 19 families and more than 100 genera. Eels can be broadly classified into two categories:

• True Eels (Anguilliformes): These include freshwater eels, moray eels, and other elongated fish with reduced pelvic fins or none at all.
  
  
  
  
  
• Eel-like Fish (Not True Eels): These include species such as electric eels, which belong to a completely different order (Gymnotiformes). While similar in appearance, these are not considered true eels.
  
  
  

Some notable eel families include:

• Anguillidae (Freshwater eels)
• Muraenidae (Moray eels)
• Congridae (Conger eels)
• Synaphobranchidae (Cutthroat eels)

Each species varies greatly in size, habitat, behavior, and ecological role.

Benefits of Eels to Humans and the Environment

1. Ecological Importance

Eels are key components of both freshwater and marine ecosystems:

• Nutrient Cycling: As both predator and prey, eels contribute to the balance of aquatic food webs. They feed on smaller fish, crustaceans, and insects, while also serving as food for larger predators like birds, sharks, and humans.
• Habitat Maintenance: By burrowing and hiding in sediments or crevices, eels can help maintain the structural integrity of riverbeds and coral reefs.
• Biodiversity Indicators: The health and migration patterns of eel populations can signal changes in water quality, climate conditions, and ecosystem integrity.

2. Economic and Nutritional Value

Eels are a valuable food resource in many parts of the world:

• Culinary Delicacy: Particularly in East Asia and parts of Europe, eel is considered a luxury food item. Japanese dishes like unagi (grilled eel) and kabayaki are globally recognized.
• Fishing and Aquaculture: Eel fishing is an important industry in countries such as Japan, China, the Philippines, and parts of Europe. Eel aquaculture is also a significant economic sector, though it faces sustainability challenges.
• High Nutritional Value: Eel meat is rich in omega-3 fatty acids, protein, vitamin A, and vitamin E, contributing to cardiovascular and eye health.

3. Cultural and Historical Significance

• Traditional Knowledge: Indigenous and local communities have long relied on eels as a sustainable food source and part of their cultural heritage. For example, the Māori in New Zealand have a long history of harvesting longfin eels (Anguilla dieffenbachii).
• Folklore and Mystery: The eel's secretive spawning habits and long migrations have inspired myths and legends in various cultures, reinforcing its mysterious status.

Conservation Challenges

Despite their importance, many eel populations are in decline:

• The European eel is currently listed as Critically Endangered by the IUCN due to overfishing, habitat loss, pollution, and barriers to migration like dams.
• Illegal trade of juvenile eels (elvers or glass eels) is a growing concern, especially in Europe and Asia.
• Climate change and oceanic shifts are also affecting eel migration and breeding success.

Sustainable fishing practices, habitat restoration, and international cooperation are crucial to preserving eel populations for future generations.

Conclusion

Eels are far more than just slippery fish—they are ancient, adaptable, and essential. With nearly 800 species spread across the globe, eels contribute significantly to aquatic ecosystems, support cultural and culinary traditions, and offer nutritional and economic value to millions. However, they also face serious threats that demand urgent attention. Protecting eels means safeguarding biodiversity, honoring cultural heritage, and preserving a unique link between the land and the sea.

Sources and References

1. FishBase
   Froese, R., & Pauly, D. (Eds.). (2025). FishBase. www.fishbase.org
• A comprehensive database of fish species, including eel taxonomy and distribution.
2. International Union for Conservation of Nature (IUCN)
   IUCN Red List of Threatened Species. (2025). www.iucnredlist.org
• Provides conservation status for species like the European eel (Anguilla anguilla), listed as Critically Endangered.
3. National Oceanic and Atmospheric Administration (NOAA)
   NOAA Fisheries. (2023). American Eel Overview. www.fisheries.noaa.gov
• Offers information on the life cycle, habitat, and management of American eels (Anguilla rostrata).
4. FAO – Food and Agriculture Organization of the United Nations
   FAO Fisheries & Aquaculture Department. (2020). Eel Fisheries and Aquaculture. www.fao.org
• Discusses global eel fisheries, aquaculture practices, and sustainability challenges.
5. ScienceDirect / Elsevier Journals
   Tesch, F. W. (2003). The Eel. Blackwell Publishing.
• A foundational scientific text on eel biology, behavior, and ecology.
6. Nature Journal
   Aoyama, J. (2009). Life History and Evolution of Migration in Catadromous Eels (Genus Anguilla). Ecological Research, 24(4), 795–806.
• Provides scientific insight into eel migration and spawning in the Sargasso Sea.
7. National Geographic
   National Geographic Staff. (2022). Secrets of the Eel’s Epic Journey to Reproduce. www.nationalgeographic.com
• Explores the mysterious life cycle and migration routes of freshwater eels.
8. New Zealand Department of Conservation (DOC)
   DOC. (2023). Longfin eel – Tuna. www.doc.govt.nz
• Covers the cultural and ecological significance of the New Zealand longfin eel (Anguilla dieffenbachii).