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How do catadromous eels differ from anadromous salmon?
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Diodon hystrix is a species of porcupine fish. These fishes are short and broad-bodied, with large eyes and spines covering their skin. Like puffer fishes, they inflate their bodies when threatened.
The primary difference between catadromous and anadromous fish lies in the direction of their migratory life cycles:
- Catadromous fish, such as eels, spend the majority of their lives in fresh water. They migrate to the sea—specifically to marine environments like the Sargasso Sea—to spawn and die.12
- Anadromous fish, such as Atlantic salmon, spend most of their lives in the ocean. They migrate into fresh water, often returning to their natal rivers, to spawn.32
While both groups exhibit complex migratory behaviors to complete their life cycles, their environmental requirements for maturation and reproduction are essentially reversed. In both cases, these migrations are critical for the survival and dispersal of the species, often involving remarkable navigation using environmental cues such as the Earth’s magnetic field and water chemistry.32