The primary distinction between a gecko and a lizard is one of classification, not a contrast between two separate groups. Geckos are a highly specialized lineage that falls within the broader definition of a lizard. The confusion arises because the term “lizard” is often used colloquially to describe the thousands of other species that do not belong to the gecko family. While all geckos are considered lizards, the term “lizard” generally refers to the remaining diverse families that lack the unique traits seen in geckos.
Understanding the Taxonomic Link
The formal relationship between geckos and other lizards is defined by their place in the biological classification system. Both geckos and all other lizards belong to the Order Squamata, the largest group of reptiles that also includes snakes and amphisbaenians. Within this order, lizards are categorized under the suborder Lacertilia, which encompasses over 7,000 species worldwide.
Geckos represent a distinct branch within this suborder, belonging to the infraorder Gekkota and the Family Gekkonidae. This family includes approximately 1,500 species that share a common set of unique characteristics. Other well-known lizards belong to different families like Iguanidae (iguanas), Scincidae (skinks), and Agamidae (dragons), which share the general lizard classification but lack the specific traits of the Gekkonidae family.
Distinct Physical Traits
The most obvious physical traits that set geckos apart from other lizards relate to their eyes and feet. The majority of geckos lack movable eyelids, a common feature found in most other lizard species, such as monitors and chameleons. Instead, their eyes are protected by a fixed, transparent scale known as a spectacle, which keeps the eye moist and clean.
Because they cannot blink to clean the spectacle, geckos must regularly use their tongues to wipe the eye surface. A notable exception is the Eublepharidae family, which includes the Leopard gecko, one of the few geckos to possess movable eyelids.
Geckos are instantly recognizable by their highly specialized feet, which grant them an unparalleled ability to climb vertical surfaces and walk upside down. This adhesive power comes from toe pads covered in microscopic parallel ridges called lamellae. These lamellae are densely covered with millions of tiny, hair-like structures known as setae.
The tips of these setae interact with the molecules of the climbing surface, generating a powerful attraction through weak Van der Waals forces. In contrast, most other lizard families rely on claws for traction or simple friction for climbing, or they are exclusively terrestrial and lack adhesive mechanisms.
Unique Sensory and Behavioral Features
Beyond their morphology, geckos display unique behavioral patterns and sensory adaptations. Geckos are unique among lizards for their ability to vocalize, producing distinct, loud sounds for communication. These vocalizations include chirps, clicks, and barks, which are used for establishing territories, attracting mates, and signaling distress.
Most other lizard species, such as iguanas or skinks, are generally quiet, relying on visual displays, body movements, and occasional hisses for communication. Geckos often use these sounds, which can even give them their name, such as the Tokay gecko, whose call resembles its name.
While many common lizards, including chameleons and bearded dragons, are diurnal (active during the day), geckos are typically nocturnal. This nighttime activity helps them avoid the intense heat of arid environments and allows them to hunt insects active after sunset.
The skin of a gecko is generally more delicate and softer than the scales of many other lizards, often appearing granular or velvety and nearly translucent. In contrast, many other lizards possess tougher, larger, and more plate-like scales that are often rougher to the touch.