external image uroplatus.jpg
GeckoBy:Tsitsi Moyo

1. Classification/Diagnostic characteristics
  • Geckos are part of the Chordate phylum. Chordates are classified as a specific kind of deuterostomes, which are simply animals that have a mouth in which forms at the opposite end of an embryo from a blastophere, and a blastophere that will eventually develop into an embryo. Common characteristics of chordates are that they have a notochord, a hollow dorsal nerve, and a tail. More specifically, Geckos are lepidosaurs, which fall under the classification of Reptiles. Reptiles are vertebrates, meaning they have a vertebral column that serves as skeletal support.
  • Geckos have the ability to camouflage themselves by changing the color (and sometimes pattern) of their skin to blend in with their surroundings. It is said that color of the skin can reflect mood or emotions of the gecko. Additionally, geckos have a detachable tail. At even the slightest touch or bite by a predator (mainly snakes and birds)the geckos can drop their tails and run away. Geckos are then able toregrow their tails. (Jillian Bunis)
  • Geckos have large heads, short and fat bodies, a large fat-storing tail, and four limbs on which it walks. They are nocturnal and adept climbers.
external image Leopard-Gecko-Body-Structure.jpg-http://www.auroville.org/environment/web_of_life/geckos.htm

2. Relationship to humans
  • The main way in which geckos relate to humans is that they are sometimes housepets.
  • Certain geckos, when provoked, can bite a human. The largest gecko (tokay gecko) has a particularly nasty bite and tends to hold on for extended amounts of time. Wild caught geckos may carry parasitic or bacterial infections. Bitten children should seek medical care because their immune system is not developed as much as adults. -http://www.reptilechannel.com/lizards/lizard-care/lizard-bite.aspx

Some geckos are talented enough to land acting roles.
Some geckos are talented enough to land acting roles.
3. Habitat and Niche
  • Although geckos are believed to have developed in an estuarine environment, one in which fresh water and salt water meet, they have developed the ability to live in a variety of different places currently. Geckos can be seen living in fresh water, marine land, aerial land, and are also commonly found on terrestrial land. Reptiles are also found in a variety of different climates (they are able to survive in warm climates because of their skin which prevents water loss). Geckos eat insecects and are eaten by snakes, large birds, and some mammals.-http://www.britannica.com/EBchecked/topic/227649/gecko
4. Predator Avoidance
  • Geckos developed their main forms of predator avoidance through their development of jaws and teeth. In the beginning, jaws made it easier for geckos as well as other vertebrates to get hold of and consume prey. Following the development of jaws, teeth formed which helped geckos to further break down and chew their prey entirely.

  • A classic gecko defense mechanism is autotomy, or self amputation. Geckos an shed part of their tail and flee away from predators. The detached tail will [[#|continue]] to wiggle, deceiving and distracting the attacker's attention. The gecko can regenerate its tail, usually taking a couple of weeks; the structure is partially different, however, as the tail will contain cartilage rather than bones and the skin will be discolored.- http://herptiles.consulnetjdm.dyndns.org:8081/caudalautotomy.html (BHu)
  • Geckos also have adapted the use of camouflage in order to be harder for their predators to find. For instance, one particular species, the Uroplatus gecko, has developed a leaf-like tail and a color that is similar to tree bark, which makes it difficult for them to be spotted by predators. (Colin Gray)- http://savethereptiles.wordpress.com/2010/01/05/the-art-of-camouflage-gecko-style/
Tiny strip of gecko foot tape can stick 700 pounds to glass
Tiny strip of gecko foot tape can stick 700 pounds to glass

Uroplatus gecko:
http://www.stanford.edu/~siegelr/madagascar/madagascar2007/IMG_1293%20uroplatus.jpg (Prashant)

5. Nutrient acquisition
  • The development of teeth made for more efficient chewing and breakdown of food, which in turn led to better chemical digestion and more uptake of nutrients from food. When food makes its way through the gecko’s digestive system, it makes its way from the mouth, to the stomach, to the small intestine which serves as an organ that breaks down and food and helps to absorb nutrients. Nutrients that have been absorbed make their way to the liver whose main job is to take in the nutrients before they exit on their way to other parts of the body.

6. Reproduction and Life Cycle


Here we see the development of a salamander. It originally starts with an egg laid in water which new evolves into a larva and then with time we have a salamander. (evan).

  • Geckos reproduce through the process of gastrulation. The gastrulation process is specific to reptiles and the kind of yolk that lies within their eggs. To start, blastulas form a disc of cells on top of the yolk. A flat, circular layer of cells called a blastodisc forms after cleavage, and blastodisc cells then break off to form the hypoblast, the space between the yolk and the blastodisc that contributes to the building of the extraembyryonic membrane that will later be used to aid embryo development. Embryonic formation is finally finished when the epiblast forms on top of both the hypoblast and blastodisc. Gastrulation then helps to thicken the posterior of the epiblast, thus forming a blastopore. Finally, the mesoderm and endoderm will form, two of the tree tissues layers (mesoderm, endoderm, and ectoderm) that will eventually develop into other bodily structures. It is in the mesoderm that the integral component of all vertebrates will form; the notochord (helps to provide bodily support). Eventually, eggs will hatch to give birth to gecko babies.

7. Growth and Development
  • The most notable developmental aspect of the gecko is the fact that the notochord that is developed when they are still a mere embryo is usually lost and replaced by a dorsal vertebral column that replaces the notochord in the early phases of development (the vertebral column then becomes the main support structure of the gecko).

external image animal-embryological-development.jpeg

The development of a few different animals. Shows notochord and appendage development.

8. Integument
  • Geckos have a skin that is composed of several horny scales. The horny scales provide a way for geckos to prevent water loss from their body’s surface. This prevented water loss does not enable their skin to be efficient in gas exchange, but it does allow geckos to comfortably live in dry climates.
  • A gecko's skin is composed of keratin, a type of fibrous proteins used for structural purposes in animals, and is composed of numerous layers of thin, flat cells. The keratin is categorized into three distinct layers in the gecko's skin: the stratum corneum (a compacted outer layer), the intermediate zone, and the stratum germinativum (the deepest layer that develops cells to move into the intermediate zone). When a gecko sheds, the cells in the stratum germinativum undergo mitosis and cell division to produce more cells that move up to the stratum corneum while the older cells come off and are discarded. During the shedding process, the usually inert skin cells are metabolically active and are able to heal any damaged regions of the epidermis. (2) [GW]

The picture shows an example of the integument in the gecko via the growth of protective scales.-http://en.wikivet.net/Integument_of_Exotic_Species_-_Anatomy_%26_Physiology

9. Movement
  • Geckos move by way of four legs. They have branched elastic fibers on their toe pads which better enable them to latch on to surfaces. These fibers allow geckos to move around flat horizontal surfaces, as well as smooth vertical surfaces.
  • Each of the five toes in the gecko is equipped with thousands of hair-like setae, the microscopic fibrous
structures of keratin that are no more than five microns in diameter and that blossom into hundreds of splitting ends referred to as spatular tips. The submicroscopic, funnel-shaped spatular pads measure approximately two hundred nanometers across and provide the gecko with its ability to climb nearly vertical surfaces. When the gecko presses its foot down, the toe hairs splay out and the spatulae unfurl, allowing the spatular pads to shoot out and recoil rapidly. This swift motion enables the spatulae to come into close proximity with the target surface, to the point at which intermolecular attractions, known as van der Waals forces, ensure that the adhesive forces are sufficient to allow the gecko to stick. The gecko must adjust for the proper angle and pressure when curling and uncurling its toes, a process that it can perform up to fifteen times a second. (Alexander Soloviev)-http://polypedal.berkeley.edu/twiki/pub/PolyPEDAL/MediaPress/SFChron6_19_00
external image writing-about-gecko-tape.jpg

A close-up shot of a gecko hand-

10. Sensing the Environment
  • Geckos sensing abilities come from their cerebrum, which breaks into the left and right cerebral hemispheres. In each hemisphere there are different lobes that help with the sensing of information. The left and right temporal lobe helps to process auditory sound in the auditory cortex. The left and right parietal lobes use the somatosensory cortex to aid in the process of processing stimuli relating to touch. The left and right frontal lobes control things such as reasoning, planning, decision making, and some aspects of speech. Lastly, the left and right occipital lobes use the visual cortex to control sight.
  • The Gecko is an ectotherm which means it can exhibit a wide range of body temperatures. Geckos as well as other ectoderms and control their body temperature through behavioral adaptations. They can exert this control by either moving to an rest on sun-heated rocks in the morning when their body temperatures are low, or by moving underneath a shady tree when the sun is strong during the day and their body temperatures are high. -http://www.absoluteastronomy.com/topics/Homeostasis
  • Gecko's have special eyes. Their eyes, which are their primary method of sensing the environment, allow them to see in both dim and bright light. They way it does this is much like people's eye adjusts, the pupil will either increase or decrease in size. Also, the color of their iris is dependent on their skin color. They have a special covering over their eye which protects it from dust. If any dust lands on it they simply lick it off.-http://www.auroville.org/environment/web_of_life/geckos.htm
  • Geckos have a nervous system that has two parts: the central nervous
system (brain and spinal cord) and the peripheral nervous system (neurons not in the central nervous system) When receptor cells are stimulated, like when the foot of a gecko touches the ground, the receptor cells will send a signal to the central nervous system, and the feel of the ground is perceived.- http://changingminds.org/explanations/brain/parts_brain/nervous_system.htm

11. Gas Exchange
  • Gas exchange of Geckos happens in the lungs. The rib movements of geckos help to push air into and out of the lungs. The geckos has a three chambered heart that helps to divide the blood that is highly oxygenated form the lungs form the blood that is poorly oxygenated form the rest of the body.
  • The largest difference between reptiles and their close reletives, amphibians, is within gas exchange. Reptles use their lungs throughout their entire lives while amphibians obtain them while maturing. Reptiles also lack the ability to diffuse oxygen through their skin. http://education.stonehill.edu/fieldguide/Field_Guide/Main/Rep-amph.htm

12. Waste Removal
  • Waste removal of a gecko happens in the large intestine. The small intestine sends food to the large intestine after all nutrients have been absorbed. Water, ions, and indigestible food moves into the colon. It is there where water and ions are absorbed, but remaining material becomes feces that are to exit in the rectum.

13. Enviornmental Physiology
  • Geckos are ectotherms, meaning that they regulate their body temperature based off of environmental heat sources (they are cold blooded). Geckos regulate the amounts of water in the body through their skin, for they have scales that reduce the amount of water lost on the body’s surface. Salt regulation of a gecko is controlled by way of active transport. Geckos use sodium pumps to pump sodium from inside of a cell into the blood. The sodium pump helps to create a concentration gradient across the cells for the osmosis of water to occur, thus also providing another way to regulate water intake (this helps to encourage water absorption).
  • Reptile are cold blooded vertebrates animal that incapable of maintaining a consistent body temperature on their own. They rely on the environment around them to warm up or to cool down. Their ability to move warm blood into the body core allows them to conserve energy. All the reptiles have scales, whether it can be hard or soft,large or small scale. [3]

14. Internal Circulation
  • Geckos run by way of a closed circulatory system that prevents blood and interstitial fluid from mixing. Geckos have a three chambered heart with one chamber as an atrium for receiving deoxygenated blood form the body, another chamber that oxygenated blood from the lungs, and the last chamber which is a partially divided ventricle which helps to limit the amounts of oxygen rich and oxygen poor blood that mixes. When the gecko is breathing, thus meaning pulmonary circuit resistance is high, blood moves from the right ventricle to the pulmonary artery and out the right side of the heart and blood from the left ventricle move to the left and right aortas and off to the rest of the body.

15. Chemical Control
  • Geckos have a brain similar to that of humans that helps to control signaling mechanisms within the body. The brain has a thalamus and a pituitary gland (releases critical hormones such as oxytocin, thyroid-stimulating hormone, growth hormone), as well as the critical hypothalamus. The hypothalamus is vital to controlling homeostasis within the body by controlling temperature and hormone levels, as well as the geckos ability to feed, fornicate, and respond to stressful situations using the fight or flight mechanism( which requires the hormones epinephrine and nor epinephrine).

external image I10-82-lizard.jpg

Review Questions
1. Describe how geckos utilize autotomy to avoid predation.
2. Describe how geckos regulate their body temperature.
3. What sense to gecko's heavily rely on for detecting predators in their environment?
4. What prevents water loss in geckos and allows them to live comfortably in dry climates?
5. How many living species of gecko's are there? (Cam Somers)


1. Hillis, David M., David Sadava, H. C. Heller, and Mary V. Price. Principles of Life High School Edition. Sudnerland, MA: Sinauer Associates, 2012. Print.
2. http://www.anapsid.org/basicdermatology.html