Amphibians
Giant Palm Salamander
Bolitoglossa dofleini · also called giant palm salamander, Doflein's salamander
The giant palm salamander is a stout, brown, foot-long amphibian from the wet Caribbean forests of Central America, and it is full of quiet extremes. It is one of the largest salamanders with no lungs at all. It climbs slick wet leaves on feet that work like suction cups. And it catches its dinner by firing its tongue out of its mouth faster than almost any other movement in the animal kingdom.
Overview
The giant palm salamander lives on the Caribbean slopes of Guatemala, Belize, and Honduras, in humid broadleaf forest. It reaches about 30–36 cm in total length, stout and smooth-skinned, mottled brown. It hunts small insects and spiders at night.
No lungs
Like all of its huge family it has no lungs and breathes entirely through its skin and mouth lining, which ties it to cool, constantly moist forest.
Suction-cup feet
Its toes are webbed into rounded paddles whose flat undersides act as suction pads, letting it climb smooth wet leaves, cling to bromeliad stems, and hold onto glass.
A ballistic tongue
It catches prey by shooting its tongue out on a spring-loaded mechanism: muscles slowly load elastic tissue, a catch holds it, and releasing the catch fires the tongue in a few thousandths of a second. The power output far exceeds what muscle can produce directly — the same trick used by chameleons and trap-jaw ants — and, being elastic, it keeps working on a cold night.
Status
The giant palm salamander is Near Threatened and declining as its wet forest is cleared and fragmented.
Giant Palm Salamander: common questions
How can a salamander have no lungs?
The giant palm salamander belongs to the plethodontids, the largest salamander family, and none of its roughly 500 species has lungs. Instead they take up oxygen and release carbon dioxide directly across the skin and the moist lining of the mouth and throat. This works because the animals are relatively small and slow, with a low oxygen demand, and because their skin is thin and richly supplied with blood vessels. The trade-off is a strict dependence on staying damp and cool, since skin breathing fails if the surface dries out or gets too warm, which confines lungless salamanders to humid forests, streamsides, and caves.
How fast is the salamander's tongue?
Extremely fast. High-speed film of Bolitoglossa shows the tongue reaching full extension in something like five to eleven thousandths of a second, and the mechanical power generated during that launch, measured per gram of the muscle involved, is among the highest recorded for any vertebrate movement, higher than a sprinting cheetah's legs or a jumping frog's. The tongue can be projected a good fraction of the salamander's body length to pluck an insect off a leaf, and the animal reels it back in with the prey stuck to the tip.
Why does the tongue work in the cold when muscle should not?
Ordinary muscle contracts more weakly and slowly as temperature drops, which is a problem for a cold forest animal that needs a fast strike. The giant palm salamander gets around this by not using muscle to power the strike directly. Its muscles contract relatively slowly to stretch elastic connective tissue in the tongue skeleton, a physical catch holds that energy in store, and when the catch releases, the elastic recoil fires the tongue. Elastic recoil is far less affected by cold than muscle contraction, so the salamander keeps a high-speed tongue even on a chilly night.
Is it related to the palm salamanders sold as pets?
It is one of them. Several Central American Bolitoglossa species are collectively called palm salamanders or mushroom-tongue salamanders, and a few appear in the amphibian hobby. The giant palm salamander is the largest of the group and is occasionally kept, though it is demanding, needing a cool, very humid, well-ventilated setup and live micro-invertebrate food, and much of the trade has relied on wild-caught animals from a declining species. Captive-bred stock is scarce, so keeping one responsibly is difficult.