This week's Animal Oddity is all about odd eating habits. The videos below show two kinds of salamander, the terrestrial red-legged salamander (Plethodon shermani) and the aquatic hellbender (Cryptobranchus alleganiensis), engaging in their respective feeding behaviors.
Most amphibians are visual feeders and the red-legged salamander is no exception. The movement of prey stimulates the salamander's predatory response and once honed in on, the prey item has little chance of escape.
As you'll see in this first video, the eyes can do double duty, at least in large-eyed species like the red-backed salamander.
Did you notice how the salamander "blinked" its eyes and they descended down into the head? Those big, bulbous eyes not only help the salamander see its prey, they actually help it push the prey down its throat. Most amphibians will try to eat any living thing that they can get into their mouths, including others of their own species. Pretty odd, right?
Hellbenders have tiny eyes by comparison, and find their prey through the vibrations it creates, but that makes them no less formidable hunters, as this video shows.
Watch those videos again. Now imagine eating something that is a quarter long as your body, which is the size ratio between the red-legged salamander and the waxworm. Imagine trying to catch and subdue a hard-shelled, pincher-armed crayfish with just your mouth. Amazing!
Reaching lengths of over two feet in length and weighing over 3 lbs., the hellbender is the largest amphibian species found in North America and the third largest salamander in the world, coming in behind the Chinese and the Japanese giant salamanders which are truly massive. (Considering their impressive predatory feeding behavior, the hellbender's two foot length is large enough for me!)
Red-legged salamanders are endemic to the mountains of North Carolina and are found no where else in the world. They are listed as a Vulnerable species on the IUCN Red List. Hellbenders are also native to North America, but have wider range from western New York and Maryland to Illinois down through the Mississippi watershed into the southern states. They are listed as Near Threatened on the IUCN Red List but their status and level of protection varies between states.
Sadly, they are not alone. Amphibians are dying out around the world and scientists don't know exactly why. Happily, there are a lot of things that you can do right in your own yard to help the local amphibian population out.