Color changing lizards of the Chihuahuan Desert
Search and Find!
Fig 1: Round-tail horned lizard – young specimen (Phrynosoma modestum)
The Round-tail horned lizard (Phrynosoma modestum) belongs to the family
Phrynosomatidae. It grows to 3-4 inches in adult age. Its body is flat and broad
with a short tail that ends in a round tip. On the back of its head are four spines.
This species occurs from west Texas to Arizona and into northern Mexico. It is
well camouflaged and protects itself by pressing its body against the ground and
remaining motionless when threatened. It feeds on ants and beetles and like
other lizards it hibernates during the winter. Depending on the soil and rock color,
on which it moves, it adapts its color to blend in (camouflage).
Fig 2: Young lizard over different backgrounds
Color change in lizards is well known from chameleons and commonly
associated with the purpose of providing camouflage to the animal, in order to
protect it from predators. The skin layers of the chameleons possess different
kinds of chromatophores, which are pigment containing cells. Chameleons have
four types of chromatophores:
– Melanophores (brown melanin)
– Iridophores (blue pigment)
– Xanthophores (yellow pigment)
– Erythrophores (red pigment)
Fig 3: Brown and green colored Chameleons.
The uppermost skin layer is transparent and depending on which layer becomes
activated, the color of the skin changes.
Recent studies of chameleons in their natural environment point towards a strong
use of color change for expressing the animal’s mood, rather than for
camouflage.
Some lizards of the Chihuahuan Desert, however, seem to camouflage
themselves through different coloration.
Fig 3:
Evolutionary changes in the color pattern of lizards of the Chihuahuan desert are
known from three species living at White Sands National Monument, New
Mexico. The White Sands lesser earless lizard (Holbrokia makulata), the Eastern
fence lizard (Sceloporus undulatus), and the Little striped whiptail
(Cnemidophorus inornatus) have a white to light grey coloration, which helps
them blend perfectly in with the white sand of their environment.
Fig4
White Sands form of an Earless lizard (left); sand dunes at White Sands (right)
It’s relative from Texas, the Greater earless lizard (Cophosaurus texanus) uses
color change in males mainly to indicate their breeding mood during breeding
season. Then their body takes on bright, fluorescent colors.
Fig 5: The Greater earless lizard (Cophosaurus texanus) in breeding coloration
The Greater earless lizard (Cophosaurus texanus) has a long tail and grows up
to 3-7 inches tall. The two broad, black markings on the flanks are a typical
identification mark for this lizard. It loves the midday sun and remains very active
during this hot part of the day. It run with its tail curled above the body. It feeds
on insects, which it catches in flight. Its long hind legs help it jump towards the
flying insect. Earless lizards do not have ear openings, though they have an inner
ear. According to new studies, the earless lizards seem to use their lungs for
hearing. Their lungs pick up vibrations from their chest caused by sounds and
pass it on to the inner ear.
Color changing lizards of the Chihuahuan Desert
Questions:
-
Which lizard discussed demonstrated adaptive camouflage?
-
Name two reasons, why lizards may change color?
-
How do chameleons change their color?
-
Why is the Lesser earless lizard in White Sands, NM, white?
-
The male Greater earless lizard has specific markings, which?
-
What do lizards feed on?
Chihuahuan Desert Education Coalition
Questions & Answers:
-
Which lizard discussed demonstrated adaptive camouflage?
o Round-tail horned lizard (Phrynosoma modestum)
-
Name two reasons, why lizards may change color?
o To signal a certain mood (threat, breeding mood)
o As a matter of camouflage
-
How do chameleons change their color?
o With the help of chromatophores (cells containing different
pigments) in skin; the uppermost layer is transparent
-
Why is the Lesser earless lizard in White Sands, NM, white?
o A mutation that prevents expression of other pigments as an
adaptation to the white environment.
-
The male Greater earless lizard has specific markings, which?
o Two wide black stripes on the sides
-
What do lizards feed on?
o Insects
Chihuahuan Desert Education Coalition