external image Tokay_geckoB.jpg1.


Gecko!Brett Shostek!
Brett Shos
tek


leopard-gecko.jpg






(9) (JLev)










Classification/Diagnostic characteristics:

Domain: Eukarya
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
There are several families of geckoes.

Geckoes are a member of the subgroup of lizards, lepidosaurs. The skin of geckoes is covered with horny scales. Geckoes have a three chambered heart. Geckoes have four limbs unlike some other lepidosaurs. Geckoes have microscopically branched elastic fibers on their toe pads, which grip surfaces using molecular scales atomic forces. They range from 2cm to 60cm. They cannot blink.

They can be easily identified by their amazing ability to walk up smooth vertical surfaces, even glass. This is possible because of the fibers on the bottoms of their feet. (4) (SJ)




Relationship to humans:

Humans are using biomimicry in that they are mimicking the toe pads of the geckoes to create new adhesives that might be used in the vacuum of space or even in the assembly of electronic microdevices! Geckoes are also kept as pets.

Geckoes are becoming more endangered due to habitat loss and pollution. May exotic ones are caught in the wild and sold illegally.(12)(KG)

In the
Philippines, Malaysia, China and South Korea the Tokay geckos are believed to have medicinal properties Their saliva and organs are claimed to cure everything from asthma to AIDS. No scientific data has been produced to prove any of these claims and it appears that it was simply a rumor on the internet that got blown out of proportion. The illegal Tokay gecko trade has grown into a multi million dollar industry with large geckos fetching up to 1200 dollars. Laws banning the trapping, sale, and consumption of these animals are in place in most south east Asian countries and has become a serious issue with many Asian governments.(15) (DA)

The foot pads of the geckos are what scientists are trying to model a new type of bandage after. Because the foot pads of the gecko have such amazing holds these bandages could possibly be used in place of stitches in the near future. (MDS)[1]

Geckos are widespread and adaptable and pose no threat to humans at all, they will live happily side by side with humans usually making a home where they can easily access a ceiling light that attracts insects. (TM)



Habitat and Niche:

Geckoes are found in warm climates across the globe.

They are a species of lizard that is found in the temperate and tropical regions of world, so they more commonly inhabit places around the Equator and place in the southern hemisphere. In these warmer regions, geckos are found across a variety of habitats including rocky deserts, mountains, jungles, forests, grasslands, and even urban areas where a gecko creeps into people's homes. Unfortunately, today geckos are threatened with extinction due to habitat loss and pollution by humans. (4) (PS)



Predator Avoidance:

Geckoes come in a variety of colors often to camoflauge themselves. they also often have a keen sense of hearing and sight.

Instead of eyelids, geckos have a transparent membrane that cover their eyes which allow them to always be alert and watching their surroundings for approaching predators. Because of this, geckos lick their eyes to keep them clean and moist instead of blinking. (8) (BH)

When attacked, geckos can release skin instead of a limb. Whatever part of skin the predator grabs is released, and this only happens with the skin is seized - which contrasts to tail droppings where the tail can drop before it is grabbed. This is called the fragile skin trait. (5) (MC)

When a leopard gecko finds itself the victim of a predator, they can force their tail to fall off. As the detached tail wiggles around, the predator is distracted and the gecko can more easily escape to one of its nearby burrows. Over time, the lost tail will regenerate. The regenerated tail will not have the attractive whirls the original tail had and will be bulbous in appearance and perhaps shorter than the original. (8)(KG).

Like many animals that can regenerate their limbs, geckos and lizards can easily detach their tails because their blood cells, bones, nerve cells, and skin can be separated at any place along the limb. (5) (HSC)



Nutrient Acquisition:

Most geckoes are insectivores.

They are carnivorous animals, and their diet depends largely upon their size. Most rely primarily on insects, but larger geckoes will hunt small reptiles, birds, and even mammals such as mice. (4) (SJ)

Because they are insectivores, geckos eat mealworms, wax worms, crickets, and different insects. Geckos more specifically leopard geckos hunt for their own food and don't eat dead animals. They also eat spiders, moths, and ants. After eating their meal, geckos keep fat in their tails.(13)(NC)



Reproduction and Life Cycle:

Most geckoes sexually reproduce. They lie amniotic eggs. These amniotic eggs are relatively impermable to water and thus allow the embryo to develope in a contained aqeous environment. The calcium-impregnanted shell of the egg retards evaporation of the fluids inside but permits passage of O2 and CO2. Th egg also stores large quantities of food, called the yolk. However, some geckoes reproduce using parthogenesis, which is a form of asexual reproduction. This is the developement of an unfertilized egg. Sexual maturity is usually reached within the first year of life.

After mating, the female will lay 2 sticky eggs that are white with a soft shell. The eggs quickly harden to protect the developing gecko. The incubation period, time it takes to hatch, can be 1 to 3 months, mainly depending on the species of gecko. The female gecko is not known to nurse or care after the gecko after they hatch. [2] (SM)

Sexual maturity in the gecko is determined by overall body mass rather than age, and geckos in captivity reach maturity faster than the geckos in the wild. Geckos are small creatures whose bodies divert more energy to reproduction rather than to growth, but they tend to live on average at least 15 years. (9) (BB-V)



Growth and Developement:

Gecko eggs take a few months to hatch, after that they grow anywhere from 2cm to 60cm.

external image gecko-egg.jpg
http://mahadewi-cakep.blogspot.com/ (JLau)



Integument:

Geckoes have horny scales to protect their internal organs. The scales also maintain homeostasis by maintaining their body temperature depending on what environment they are in.

Some geckoes burrow in sand to cool off with aid of the scales.(7)(Shwetha)
Close up of scales used for protection. (LC)
Close up of scales used for protection. (LC)

Geckos have millions of microscopic hairs covering their feet. These hairs separate into even smaller tips of only about 200 nanometers in diameter. This allows for very "intimate" (Kellar) contact with any surface the gecko is trying to climb and enables the gecko to climb practically any surface with ease. (MDS) (17).



Movement:

Geckoes have four legs that they use to maneuver around on land.

Gecko toes have a special adaptation that enables them to adhere to just about any surface without using liquids or surface tension, whether the surface is wet, dry, smooth, or rough. This adhesion can be switched mechanically on and off based on whether the gecko is sliding against a surface or relaxing its sliding tension. The expanded toe pads allow geckos to climb vertically on smooth surfaces, and the secret to the adhesion is in the around 14,000 hair-like setae that are on every square millimeter of a gecko's footpad. (3) (JF)

Gecko_foot.jpeg(shwetha)(14)



Sensing the Environment:

Geckos have eyes to see. They also often have very good perception of sound. They can also sense temperature through their scaly skin.

Geckos sense and perceive their environment in the same way as other vertebrates. They have a nervous system comprised of a central nervous system (brain and spinal cord, bundles of neurons, transmitter cells) and peripheral nervous system (neurons outside the central nervous system) which consist of the sensory neurons (receptor cells). When the sensory neurons are stimulated in one of the receptor organs, such as pressure from the ground on a gecko's toe, the receptor cells in turn stimulate the spinal cord which transmit the information to the brain, where the touching sensation is perceived. [6] (AY).

Geckos have long tongues which enables them to sense their external environment because they flick them out to collect air particles. Those air particles then come in contact with the vomeronasal organ (controls sense of smell) after the tongue retracts back into the mouth. This way, the gecko is able to sense its environment more effectively and can have another means of detecting objects around it (8) (E.S.S.).



Gas Exchange:

Because of the scales on the gecko, skin is unavailable for gas exchange. Gases are exchanged in the lungs which are much larger in surface area than those of amphibians. The gecko forces air in and out of its lungs by bellow like movements of its ribs.

The Geckos use their ribs as their respiratory system when they "breathe". When a gecko breathes it is very similar to that of a human because it is bidirectional in the way that air comes in one way, and out the other. (16) (ES)



Waste Removal:

Geckos remove wastes in the form of the semi-solid, uric acid. Geckos excrete uric acid in order to conserve water.

After passing the stomach and into the small intestine, food will first have its nutrients absorbed in the small intestine. Within the colon, the large intestine, water, ions and indigestible substances will remain. Water and ions will be filtered and absorbed, while remaining material is excreted by the rectum as feces. (AWC)



Environmental Physiology:

Geckos have scales to prevent water loss. Geckos are ectotherms and often regulate their body temperature by basking in the sun. This is why they must live in warmer environments.

Because geckos are ectotherms, they cannot regulate their body temperature by themselves. Therefore, to maintain temperature homeostasis, they must modify their behavior. During the mornings, when the environmental temperature is low, geckos warm themselves up by staying in a warmer area, basking in the sun, and orienting itself such that it is perpendicular to the sun's rays (sunlight hits more surface area). As the day moves on and temperatures rise, geckos cool themselves down by moving to a colder area and either getting out of sun or orienting themselves such that they are parallel to the sun's rays (sunlight hits less surface area). Thus, by constantly modifying their behavior, geckos can maintain the body temperature necessary for function and survival. [3] (FZ)



Internal Circulation:

The three chambered heart partially separates oxygen rich blood from the lungs from deoxygenated blood returning from the body. Geckos can generate high blood pressure and can sustain a relatively high metabolism.

The gecko heart has three parts: two atria and one ventricle. The ventricle is partially separated in two by a muscular septum. The left atrium receives deoxygenated from the veins, which then gets pumped into the ventricle. At the same time, the right atria is receiving oxygenated blood from the lungs and pumping it into the ventricle. The ventricle then contracts, causing the opening in the septum to close and mostly separating the two types of blood from mixing. This allows for a higher concentration of oxygen to get to the body rather than a simple three chambered heart where the blood is has oxygenated and half deoxygenated. (10) (AA)



Chemical Control:

Hormones are primarily produced in the brain of the gecko and travel through the body of the gecko to signal changes. Geckoes differ in hormones as well as behavior based on sex, temperature of birth, geography, and a number of other factors.

The thyroids are involved in control of ecdysis, the process of shedding, but the parathyroids have a similar role to the parathyroids of mammals like controlling calcium and phosphorus levels(CC)



Works Cited:

1. http://www.ski.org/Vision/Eyepage/Images/Tokay_geckoB.jpg2. Hillis, David M. Principles of Life. Sunderland, MA: Sinauer Associates, 2012. Print.3. https://sci-quest.org/sites/all/themes/sciquest/documents/Gecko%20Feet%20Information.pdf
4. http://a-z-animals.com/animals/gecko/
5. http://www.anapsid.org/autotomy.html6. http://changingminds.org/explanations/brain/parts_brain/nervous_system.htm
7. http://www.tcd.ie/Biology_Teaching_Centre/assets/pdf/by2207/mwby2207/mwby2207-lecture3.pdf8. http://www.journalofvision.org/content/9/3/27.full9. http://www.moonvalleyreptiles.com/crested-geckos/health/growth-rates
8. "» Leopard Gecko Characteristics." Leopard Gecko Characteristics. Herp Center Network, 2004. Web. 13 Dec. 2012. <http://www.herpcenter.com/leopard-gecko-care/leopard-gecko-characteristics.html>.
9. http://www.seapets.co.uk/blog/how-to-guide/6-considerations-for-leopard-gecko-care.html
10. Kimbal, John. "Animal Circulatory Systems." Animal Circulatory Systems. N.p., 22 Dec. 2010. Web. 15 Dec. 2012.
12.http://a-z-animals.com/animals/gecko/
13.http://en.wikipedia.org/wiki/Leopard_gecko
  1. ^ http://www.wired.com/wiredscience/2008/02/gecko-grip-equa/
  2. ^ http://a-z-animals.com/animals/gecko/
  3. ^ http://uts.cc.utexas.edu/~varanus/lacertids1.html

14.
http://www.google.com/imgres?hl=en&tbo=d&biw=1016&bih=668&tbm=isch&tbnid=F_BIOAUYR0QclM:&imgrefurl=http://blogs.discovermagazine.com/notrocketscience/2012/06/27/geckos-evolved-sticky-feet-many-times/&docid=7c3945j51KhdfM&imgurl=http://blogs.discovermagazine.com/notrocketscience/files/2012/06/Gecko_foot.jpg&w=610&h=529&ei=NLvTUPPoCKux0QHxuIDYDQ&zoom=1&iact=hc&vpx=544&vpy=279&dur=578&hovh=151&hovw=168&tx=128&ty=62&sig=115331735526843433112&page=3&tbnh=146&tbnw=162&start=44&ndsp=21&ved=1t:429,r:62,s:0,i:280
15. http://www.aseanbiodiversity.org/index.php?option=com_content&view=article&id=147:illegal-trading-of-gecko-poses-threat-to-environment&catid=1:news&Itemid=10916. http://www.helium.com/items/949899-how-reptiles-breathe
17. http://geckolab.lclark.edu/dept/geckostory.html

Review Questions!


1. How is having a detachable tail an advantage for geckos? (WSS)2. Describe how geckos regulate their body temperature. (CC)
3. Describe the type of heart that Geckos possess. Why is this advantageous? (JF)4. What is the function of a gecko's scales? (DM)


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