The brille (also called the ocular scale, eye cap or spectacle) is the layer of transparent, immovable disc-shaped skin or scale covering the eyes of some animals for protection, especially in animals without eyelids. In squamate reptiles both the nictitating membrane and the eyelids have been suggested as the evolutionary origin of the brille, but embryonic studies supports the fusion of the dorsal and ventral eyelids. Brille means "spectacles" or " glasses" in German, Norwegian, and Danish. In snakes, there are no eyelids and the brille is clear and cannot be distinguished, except when the animal is becoming ready for

ecdysis Ecdysis is the moulting of the cuticle in many invertebrates of the clade Ecdysozoa. Since the cuticle of these animals typically forms a largely inelastic exoskeleton, it is shed during growth and a new, larger covering is formed. The remnant ...

. At that time, it becomes cloudy and is visible as a cover over the eye. When the snake moults, the brille is also shed, generally inside out, as part of its skin. The brilles protect their eyes from dust and dirt and give them a "glassy-eyed" blank appearance.

Snake Snakes are elongated limbless reptiles of the suborder Serpentes (). Cladistically squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales much like other members of the group. Many species of snakes have s ...

s, flap-footed lizards, night lizards, and some

skink Skinks are a type of lizard belonging to the family (biology), family Scincidae, a family in the Taxonomic rank, infraorder Scincomorpha. With more than 1,500 described species across 100 different taxonomic genera, the family Scincidae is one o ...

s have brilles. All

gecko Geckos are small, mostly carnivorous lizards that have a wide distribution, found on every continent except Antarctica. Belonging to the infraorder Gekkota, geckos are found in warm climates. They range from . Geckos are unique among lizards ...

s except those in the subfamily Eublepharinae (eyelid geckos) possess brilles. Some groups of

bony fish Osteichthyes ( ; ), also known as osteichthyans or commonly referred to as the bony fish, is a Biodiversity, diverse clade of vertebrate animals that have endoskeletons primarily composed of bone tissue. They can be contrasted with the Chondricht ...

have a transparent eyelid known as the adipose eyelid. Some reptiles, mammals and birds have a translucent third eyelid that moves horizontally across the eye called the nictitating membrane.

References

{{reflist * ''Keeping and Breeding Geckos'', Hermann Seufer, 1991. Snake scales

See also

References