Australia is
home to some of the world’s most beautiful and deadly snakes. There are currently 93
Species of Elapid in Australia. Elapids are classified usually by their short
fixed fangs at the front of their mouth. Elapids are a extremely diverse group
of snakes. Ranging from the nitrious 5 meter King cobra (Ophiophagus hannah) found in India, to the 40cm Small eyed snake (Rhinoplocephalus nigrescens) found on
the east coast of Australia. Most of which are found here in Australia are long,
slender, extremely fast moving and very alert snakes. Remaining active during
the day moving constantly to find food. However there is a Genus of Elapid
which is slightly unique in their appearance and behavior, these are the Acanthophis species or death
adders. There are currently 4 species of
death adder in Australia along with a small number of other species found in
Papa New Guinea.
Photo by Ryan Pilgrim
Pilbara Death Adder
Acanthophis wellsi
Death adders
belong to the Elapid family however at first glance they would appear to be
more at home with the Vipers. They resemble the European adders, Puff adders and other
viper species, they are short stout snakes not well adapted for traveling long
distances in search of food but instead have evolved to become effective ambush predators. Death
adders will bury themselves in the leaf litter or sand and wait patiently for
prey to come to them. There have evolved a lure at the end of the tail which
they leave exposed and wriggling in order to entice a small animal closer. They
possess a lightning fast strike which has been measured at 0.2 of second from a
standing ambush position to the target. This tactic of sit and wait in ambush
is common throughout the viper family and a number of species which also use
this caudal luring technique to attract prey.
Puff Adder
Bitis arietans
http://www.venomousreptiles.org/classifieds/detail/12133
28/4/14 18:37
Photo by Ryan Pilgrim
Common Death Adder
Acanthophis antarcticus
It is clear
that this is an excellent example of convergent evolution at work. There are no
vipers in Australia, this indicated the death adders have independently evolved
this style of prey capture alongside vipers found all across the globe. Death
adders produce a neurotoxic venom which can affect the nervous system and
symptoms relate to neuromuscular failure leading to paralysis and breathing
failure. This is where the similarities end as vipers possess a haemotoxic venom
which attacks red blood cells either causing serious haemorrhaging or clotting
of the blood this causes multiple organ failure and commonly necrosis at the
bit site.
That is indeed an intriguing case of convergent evolution. Are there other sit-and-wait ambush snake species (that are venomous) in Australia? Is their venom delivery system the same as that of an elapid or does it too resemble that of a viperid? Interesting!
ReplyDeleteThe majority of snake species are ambush predators however most elapids in Australia, will seek out a rodent run and wait in ambush for it to pass. They also hunt down burrows for small reptiles and mammals. There aren’t any other elapids in Australia that use caudal luring. There are a few exotic viper species that do. From what I can see Death adder delivery system is more like an elapid then a viper. They have small fixed fangs rather than independently moving large fangs. Also they produce smaller amounts of venom. Vipers generally have large venom glands with larges fangs so they can inject venom deep into the muscles where it will do most damage.
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