Electric eel
Phylogeny

Electric eels form a clade of strongly electric fishes within the order Gymnotiformes, the South American knifefishes. Electric eels are thus not closely related to the true eels (Anguilliformes). The lineage of the Electrophorus genus is estimated to have split from its sister taxon Gymnotus sometime in the Cretaceous. Most knifefishes are weakly electric, capable of active electrolocation but not of delivering shocks. Their relationships, as shown in the cladogram, were analysed by sequencing their mitochondrial DNA in 2019. Actively electrolocating fish are marked with a small yellow lightning flash. Fish able to deliver electric shocks are marked with a red lightning flash.
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