Eels are elongated, fish-like creatures found in diverse aquatic environments, from freshwater rivers to the deep ocean. Their unique appearance often raises questions about their potential danger to humans. While some species can pose risks, this concern is often rooted in a mix of fact and misconception. Understanding the specific capabilities of different eel types helps clarify the reality behind these encounters.
Electric Eels: The Shock Hazard
Electric eels are a type of knifefish, more closely related to carp and catfish than true eels. These freshwater fish, found in South American rivers, are renowned for their ability to generate powerful electric discharges using specialized organs called electrocytes. An adult electric eel can produce a shock ranging from 600 to 860 volts. While the voltage is high, the amperage is relatively low, typically around 1 amp.
A single shock can cause intense pain, muscle spasms, and temporary paralysis. Although rarely fatal to healthy adults, the primary danger lies in secondary effects like drowning, especially if shocked while submerged. Multiple shocks or shocks to individuals with heart conditions can increase risks, potentially leading to respiratory failure or cardiac arrest. Encounters typically occur in murky or shallow waters where these eels might be lurking, often when humans inadvertently disturb them.
Moray and Conger Eels: The Bite Threat
Moray and conger eels pose a biting threat due to their powerful jaws and sharp, often backward-pointing teeth. Moray eels, in particular, possess a second set of pharyngeal jaws in their throat, which can project forward to secure prey. These eels are ambush predators, typically hiding in rocky crevices, coral reefs, and shipwrecks. Bites often result from mistaken identity, defending territory, or provocation, such as feeding attempts by divers or fishermen.
Their bites can inflict deep lacerations, punctures, and significant bleeding. A substantial risk comes from secondary infections due to bacteria present in their mouths, including Vibrio species. While moray eels are generally not aggressive unless provoked, their bites can be painful and may lead to tissue loss or nerve injury in severe cases. Conger eels generally prefer to flee rather than attack unless provoked.
Other Eel Species and Misconceptions
The vast majority of the over 800 known eel species pose little to no danger to humans. Common freshwater eels, such as the American and European eels, along with many marine species like garden eels and snake eels, are typically shy and harmless, preferring to avoid contact. Many perceived “eel attacks” are often cases of mistaken identity or occur when the eel feels threatened or provoked.
A common misconception is that all eels are venomous. While many true eels, including morays and congers, possess toxic proteins called ichthyotoxins in their blood serum, these are not delivered through venom. These ichthyotoxins can cause muscular cramps if raw eel blood enters the bloodstream, but they are denatured and rendered harmless by heat during cooking. Ciguatera fish poisoning can also occur if certain moray eels consume contaminated smaller fish, but this toxin is not produced by the eel itself and is not destroyed by cooking.
Encountering Eels Safely
Avoiding dangerous encounters with eels requires awareness and respectful behavior. Never provoke, touch, or attempt to feed wild eels. Divers and swimmers should be aware of eel habitats, such as murky waters for electric eels or rocky crevices and coral reefs where moray and conger eels reside. Avoiding placing hands or feet into hidden crevices, especially in rocky areas, is a crucial precaution. Maintaining a respectful distance if an eel is sighted allows both humans and eels to remain safe.
In the event of an electric shock, calmly exit the water and seek medical attention, even if symptoms seem mild. For bites, thoroughly clean the wound with soap and water immediately. Apply pressure to stop any bleeding, and apply an antibacterial ointment before covering the wound with a sterile bandage. Due to the risk of infection from bacteria in the eel’s mouth, medical attention is advisable for any bite, especially if it is deep or causes significant bleeding.