Head to head
Cope's Giant Salamander vs Idaho Giant Salamander
Cope's giant salamander and the Idaho giant salamander both belong to the same small genus of giant salamanders, but one keeps its gills for life while the other transforms into a terrestrial adult in the more typical way.
| Cope's Giant Salamander | Idaho Giant Salamander | |
|---|---|---|
| Genus | Dicamptodon | Dicamptodon |
| Completes metamorphosis | Rarely | Typically yes |
| Adult form | Permanently aquatic, gilled | Terrestrial, lunged |
| Range | Olympic Peninsula, coastal Washington | Rocky Mountains, Idaho and Montana |
| Geographic isolation | Coastal Pacific Northwest | Landlocked, hundreds of miles inland |
| Vocal ability | Not well documented | Capable of growling or barking |
| Habitat | Cold mountain streams | Cold mountain streams |
| Conservation status | Near Threatened | Near Threatened |
Cope's Giant Salamander vs Idaho Giant Salamander: common questions
Why doesn't Cope's giant salamander grow up like the Idaho giant salamander?
Cope's giant salamander is permanently neotenic, meaning most individuals rarely complete metamorphosis and instead retain gills and an aquatic lifestyle for their entire adult life, a trait not fully understood but possibly linked to the specific cold, resource-rich streams it inhabits, whereas the Idaho giant salamander typically does complete metamorphosis into a terrestrial, lunged adult, following the more standard life cycle for its genus.
Were these two salamanders ever considered the same species?
Yes, both Cope's giant salamander and the Idaho giant salamander were originally part of a single, more broadly distributed giant salamander species before later genetic and structural evidence supported splitting the group into four separate species, including these two along with the coastal and California giant salamanders.
Why are these two salamanders found so far apart geographically?
Cope's giant salamander remains restricted to coastal Pacific Northwest streams on Washington's Olympic Peninsula, while the Idaho giant salamander is isolated hundreds of miles inland in the Rocky Mountains, a split generally understood to reflect a once broader, continuous range that fragmented over a long span of geological time, leaving the Idaho population as an inland relict.