Abstract
Gekkonidae family is discussed in the paper. Geckos are among the most geographically widespread and species-rich lineages of vertebrates. They are sufficiently present in Qatar as well. A comprehensive description of the family peculiarities started with the analysis of general characteristics of lizards and the features they obtained throughout the evolution. After this, the specific physiological properties of geckos were outlined. In this way, it was possible to identify both the common and unique qualities of the given biological family.
Introduction
Within Qatari borders, the plethora of habitats including deserts and shorelines are comprised. As a result of geographical and habitat heterogeneity, the wildlife in the country is characterized by diversity. It is possible to find a lot of mammals (e.g., gazelles, sand cats, camels, etc.), birds (e.g., gulls, falcons, sparrow-larks, etc.), fish, and insects there. However, the given paper will focus on reptiles − lizards and geckos, in particular. Along with nocturnal mammals, such as desert hares, geckos are represented as a common natural feature of the country. Although lizards and geckos are terrestrial vertebrates, their biological characteristics are different from many other groups of terrestrial animals in many ways. Their major physiological and biological peculiarities will be discussed in the given paper.
Lizards: General Characteristics
Reptiles are typical terrestrial animals − they move by crawling, groveling on the ground. They belong to the Amniotes group comprising tetrapod vertebrates (Jensen et al. 2013). The major biological and structural features of reptiles helped their ancestors leave the water and spread widely across the earth. These features include internal fertilization and the laying of eggs covered with a dense protective shell, which contributes to the reptile species’ development on the land (Rheubert et al. 2014).
Respiratory and Muscular-Skeletal Systems
The breathing in reptiles is performed by lungs which, compared to the lungs of amphibians, have a more complex structure. The advancement of reptiles’ respiratory system became possible due to the development of a new section of the skeleton in them − the thorax (Taylor et al. 2010). The thorax is formed by a few paired ribs that connect at the dorsal side and the spine, as well as at the ventral side and the breastbone. Sue to a well-developed muscular system, the ribs are mobile and contribute to the expansion and narrowing of the chest during the respiration process (Taylor et al. 2010).
Blood Circulation System
Changes in the structure of reptiles’ respiratory system are closely related to changes in the blood circulation. Most reptiles have a three-chambered heart and two circles of circulation, similar to amphibians (Jensen et al. 2013). However, the structure of the reptiles’ heart is more complex. There is a septum in its ventricle and, at the time of contraction, this septum almost completely divides the heart into the right (venous) and left (arterial) halves (Jensen et al. 2013). Such a structure of the heart differentiates reptiles from amphibians − the location of the main vessels delineates the venous and arterial streams more clearly. Therefore, the body of reptiles is supplied with more oxygenated blood. The main vessels of the large and small circles of the circulation are typical for all terrestrial vertebrates. The main difference between the small circle of blood circulation in amphibians and reptiles is that skin arteries and veins had disappeared in reptiles, and the small circle of their blood circulation includes only pulmonary vessels (Jensen et al. 2013).
Gekkonidae
The family of geckos unites about 80 genera and over 900 species of lizards of medium, small, and very small sizes (Ananʹeva et al. 2006). They are widely distributed mainly in tropical and subtropical regions. All species included in the family are associated with some common anatomical features manifested in the structure of the vertebrae, skull, and skeleton. The trunk of most geckos is dense, flattened, and the head is relatively large and covered with granular scales or numerous small polygonal scutes (Castilla et al. 2013). The length and shape of the tail vary. In some groups of geckos, the tail serves as a storage area for fat. Another interesting feature of geckos is the ability to autotomy, i.e., dropping the tail in case of danger, and tail regeneration (Ananʹeva et al. 2006).
The body of reptiles has protective formations in the form of scales, which cover the body entirely ensuring a high level of protection. The skin is always dry, and the fluids cannot evaporate through it (Ananʹeva et al. 2006). It is the reason why reptiles can live in dry places. The coloring of various species of geckos is very diverse. In most cases, it is bright with clearly distinctive patterns of pigmentation in the form of stripes and dots. At the same time, the color of lizards’ skin is adjusted to a particular habitat so that it has an excellent camouflage effect (Stevens 2016).
Among the geckos, it is possible to find species that are active either during the day or during the night. In those geckos that hunt during the daytime, the pupils are primarily round, while in the night geckos, it is usually slit-shaped (Greene 2013). Geckos also differentiate from other scaly reptiles by their ability to make sounds and use sound communications (Ananʹeva et al. 2006).
The structure of the paws of the whole gecko family should be paid special attention. “Geckos are well known for their extraordinary clinging abilities and many species easily scale vertical or even inverted surfaces” (Gamble et al. 2012, p. e39429). In many genera, the fingers are enlarged and covered by attachment plates, the arrangement and shape of which have an important systematic significance. The extremities of these reptiles end with evenly spaced feet, which have five fingers. The fingers on the inner side are small ridges covered with the finest bristles with a diameter of about 100 nm (Gamble et al. 2012). All these properties help lizards cling to surfaces.
Conclusion
The gecko family is among the most diverse and widespread group of lizards in the world. As the literature review findings demonstrate, they have a lot of unique features including vocalization and ability to cling to vertical surfaces due to the presence of multiple microscopic multi-vertebral hairs on their paws. This family of lizards is an intrinsic part of Qatari biodiversity. Geckos have adapted to live in a great variety of conditions from arid deserts to various urban objects and facilities. Despite their unpretentious character and agility, lizards are still exposed to adverse impacts of ecological deterioration. To ensure the sustainability of the gecko population in Qatar and foster the preservation of lizard diversity, the development and implementation of a proper biodiversity plan are required.
Reference List
Ananʹeva, N B, Orlov, N, Khalikov, R G, Darevsky, I S, Ryabov, S A & Barabanov, A 2006, The reptiles of northern Eurasia: taxonomic diversity, distribution, conservation status, Pensoft, Sofia.
Castilla, A, Valdeón, A, Cogălniceanu, Gosa, A, Alkuwary, A, Saifelnasr, E O H, Naimi, S A & Al-Hemaidi, A A M 2013, New record of a lizard species for Qatar: Hemidactylus persicus Anderson, 1872 (Gekkonidae), Web.
Gamble, T, Greenbaum, E, Jackman, T R, Russell, A P, Bauer, A M & Castresana, J 2012, ‘Repeated origin and loss of adhesive toepads in geckos’, PLoS ONE, vol. 7, no. 6, p. e39429.
Greene, J 2013, Reptile vision: nocturnal geckos – November 2013, Web.
Jensen, B, Van Den Berg, G, Van Den Doel, R, Oostra, R-J, Wang, T, Moorman, A F M & Eisenberg, L 2013, ‘Development of the hearts of lizards and snakes and perspectives to cardiac evolution’, PLoS ONE, vol. 8, no. 6, p. e63651.
Rheubert, J L, Siegel, D S, & Trauth, S E 2014, Reproductive biology and phylogeny of lizards and tuatara, Taylor & Francis Group: Boca Raton.
Stevens, M 2016, ‘Color change, phenotypic plasticity, and camouflage’, Frontiers in Ecology and Evolution, vol. 4, no. 14, p. 3629.
Taylor, E W, Leite, C A, McKenzie, D & Wang, T 2010, ‘Control of respiration in fish, amphibians and reptiles’, Brazilian Journal of Medical and Biological Research, vol. 43, no. 5, pp. 409-424.