Welcome back to
evolution of venom, in today’s blog topic, we will be covering amphibians that
use venom. Majority of amphibians currently found are poisonous rather than
venomous, but there are three amphibians that use venom.
The Iberian ribbed
newt or Spanish ribbed newt (Pleurodeles
waltl) is a species of newt found in central Iberian, Peninsula and
Morocco. It is the largest European newt species found and it is known for its
odd defence mechanism. When the Iberian ribbed newt is threatened or agitated,
it swings its ribs forward out of its skin so the ribs are outside of its body.
If a predator tries to bite or pick up the newt, the ribs act like venomous
barbs, injecting a milky substance into the predator causing severe pain or
death. This defence mechanism does not hurt the newt as it is able to reconstruct
the tissue around the area where the ribs broke through (Rosania, 2014). Below is
a picture of an Iberian ribbed newt.
Picture taking by Peter Halasz.
The other two
venomous amphibians are a pair of frogs with an unusual defence mechanism.
Greening’s frog (Corythomantis greeningi)
and Bruno’s casque-headed frog (Aparasphenodon
brunoi) both use bony spines located on top of their head to inject venom
into predators. Most frog species produce or secret poison to ward off predators
which makes these two frogs unique (Carlos Jared et al, 2015). The venom of
these frogs has not been studied a lot as venomous amphibians are rarer than
amphibians that produce poison. However, study suggest that Greening’s frog
venom can provoke effective nociceptive and inflammatory effects (Mendes et al,
2016). Below on the top is a picture of Greening’s frog and on the bottom is Bruno’s
casque-headed frog.
Both pictures were taken by Carlos Jared /
Butantan Institute.
Next time, we will
be covering on some interesting birds that are poisonous (not venomous as there
are no known venomous birds).
References
Rosania, K. 2014,
"Newts with superpowers", Lab Animal, vol. 43, no. 7, pp. 231-231
Carlos Jared et al.
Venomous Frogs Use Heads as Weapons. Current Biology, published online August
06, 2015; doi: 10.1016/j.cub.2015.06.061
Mendes, V.A.,
Barbaro, K.C., Sciani, J.M., Vassão, R.C., Pimenta, D.C., Jared, C. &
Antoniazzi, M.M. 2016, "The cutaneous secretion of the casque-headed tree
frog Corythomantis greeningi: Biochemical characterization and some biological
effects", Toxicon, vol. 122, pp. 133-141.
Picture references
