The common agama, red-headed rock agama,
or rainbow agama (Agama agama) is a species of lizard from
the Agamidae family found
in most of sub-Saharan Africa. The species name was formerly
applied to a paraphyletic collection of taxa, and mitochondrial
DNA analysis of various populations indicates they
represent separate species. Consequently, three former subspecies A. a. africana, A. a. boensis,
and A. a. mucosoensis are
now considered separate species, and A. a. savattieri is
considered synonymous with A. Africana.[
Its
size varies from 13 to 30 cm (5.1 to 11.8 in) in total length.[4] Males
are typically 3-5 inches longer than the average female. The agama lizard can
be identified by having a white underside, brown back limbs and a tail with a
light stripe down the middle. The stripe on the tail typically possesses about
six to seven dark patches along its side. Females, adolescents and subordinate
males have an olive green head, while a dominant male have a blue body and
yellow tail.
The agama jumps from a horizontal surface onto a vertical wall
with ease. But if that surface is slippery, the lizard loses its footing, yet
it still makes a successful landing on the wall. How? The secret is in the
lizard’s tail.
When agamas jump from a
coarse surface—which provides grip—they first stabilize their body and keep
their tail downward. This helps them to jump at the correct angle. When on a
slippery surface, though, the lizards tend to stumble and jump at the wrong
angle. However, in midair, they correct the angle of their body by flicking
their tail upward. The process is intricate. “Lizards must actively adjust the
angle of their tails just right to remain upright,” says a report released by
the University of California, Berkeley. The more slippery the platform, the
more the lizard must raise its tail to ensure a safe landing.
Balance and
counter-weight are two important functions that the tail plays in locomotion,
particularly for lizards
A lizard without a tail
would be less able to run and would not be able to walk as quickly or
efficiently as a lizard with a tail.
The
agama’s tail may help engineers design more-agile robotic vehicles that can be
used to search for survivors in the aftermath of an earthquake or other
catastrophe
Many lizards have developed a defense
mechanism called "autotomy," or, more simply, they are able to drop
their tail when they are threatened by a predator.
Lizards
that can drop their tail have "fracture planes" spaced regularly down
the length of the tail. These are either between vertebrae or in the middle of
each vertebra, depending on the species, and it is at these points where the
break can occur. Skin, muscles, blood supply, nerves, and bone separate when
the tail is dropped. After it falls to the ground, the tail starts to wiggle
and move on the ground, hopefully giving the lizard a chance to escape while
the predator is focused on the moving tail.
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