The Texas horned lizard (Phrynosoma
cornutum) is found from the south-central United
States to northern Mexico. Their
habitat is arid and semiarid open areas with limited plant cover. They also require loose soil in order
to burrow for hibernation, nesting, and insulation.
Notice how well this individual blends into the background (photo: the wikipedia files)
There are about fifteen
species of horned lizards, eight being native to the United States. They are often called “horny toads” or
“horned frogs.” However, they are
neither a toad nor a frog but the name comes
from the lizard’s rounded body and blunt snout, which resembles the
amphibians. The Texas Horned
Lizard is the largest and most widely distributed of the horned lizards.
This lizard has two
prominent horns towards the rear middle part of its head and then several
smaller horns on the sides. The
protrusions on the head are true horns since they have a boney core. However the horny spines on its sides
and back are composed of modified scales.
Its scale coloration is a mixture of brown and gray earth tones, giving
it excellent camouflage.
Horned lizards mainly eat
harvester ants, but will also include termites, grasshoppers, beetles, and
beetle larvae in their diet
What makes the Texas
horned lizard so strange is its defense mechanism. Horned lizards mainly use their camouflage to avoid
predation. However, if found their
horns and spines may act as a deterrent for many predators. The lizard may also inflate its body to
make itself look larger and less easy to swallow. But finally, if all else fails, the lizard will violently
excrete blood from its eyes! This
process is called autohaemorrhaging, or reflex bleeding. It can squirt up to 1/3 of its volume
in blood reaching up to a five-foot distance. They do this by restricting the blood flow leaving the head,
increasing the blood pressure and rupturing tiny vessels around the
eyelids. The blood is mixed with a
chemical that makes it very foul tasting to canine and feline predators. There are eight known species of horned
lizards that have this defense mechanism.
The only other known animals that will expel blood as a defense is a
genus of dwarf boas, Tropidophis,
and the European grass snake, Natrix natrix.
The Texas horned lizard is
listed as a threatened species in Texas and Oklahoma mainly due to loss of
habitat, use of pesticides exterminating their food source, and the spread of
an invasive species, the red fire ant.
The aggressive and territorial red fire ant destroys harvester ant
colonies, the lizard’s main food source.
The Texas horned lizard is now a protected species and Texas Parks and
Wildlife along with other conservation groups are studying the species in order
to shield it from any further harmful human impact.
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