Interesting Creatures… The Iguana
Kaieteur News – The Iguana is a genus of herbivorous lizards native to tropical areas of Mexico, Central America, South America and the Caribbean. 
The genus was first described in 1768 by the Austrian naturalist Josephus Nicolaus Laurenti in his book Specimen Medicum, Exhibens Synopsin Reptilium Emendatam cum Experimentis circa Venena. Previously, there were only two species in the genus; the green iguana, common throughout its range and a popular pet, and the Lesser Antillean iguana, native to the Lesser Antilles; however, genetic analysis shows that the green iguana may contain a species complex of multiple species, some of which have recently been described.
The word “iguana” is derived from the original Taino name for the species, iwanana. In addition to the two species in the genus Iguana, several other related genera in the same family have common names of the species including the word “iguana.”
ANATOMY AND PHYSIOLOGY
Iguanas can range from 1.5 to 1.8 meters (5 to 6 ft) in length, including their tail. Both species of lizard in the genus Iguana have a leaf tuft and a row of elongated scales running from the center line of their necks down to their tails. Iguanas have different types of scales that cover different parts of their body, for example, some large round tubular scales are scattered around the lateral region of the neck among smaller overlapping scales. The scales on the dorsal trunk of their body are also thicker and more tightly packed than those on the ventral side. These scales can be a variety of colors and are not always visible from close distances. They have a large round scale on their cheeks called an isympanic shield.
Iguanas have a keen vision and can see shapes, shadows, colors and move at long distances. Their visual acuity enables them to navigate through overcrowded forests and find food. They use visual signals to communicate with other members of the same species.
The tympanum, the ear of the iguana, is positioned above the isympanic shield (or “ear shield”) behind each eye. Iguanas are often difficult to spot, as they tend to blend into their surroundings and their coloring allows them to hide from larger predators.
Like most reptiles, an iguana has a three-chambered heart with two atria, one ventricle, and two aortae with systemic circulation. https://en.wikipedia.org/wiki/Iguana – cite_note-dabvp2561-7 The muscles of iguana are very light in color; this is due to the high proportion of fast glycolytic muscle fibers. These fibers are not highly vascularized and are low in myoglobin, giving them a pale appearance. This high density of fast glycolytic muscle fibers allows iguanas to move very fast for a short time, which facilitates short bursts of movement but is inefficient for long movement, as cellular respiration in fast glycolytic muscle fibers is anaerobic .
PARIETAL EYE
Many newt species, including the iguana, have a pale scale towards the back of their head marking the parietal eye. This organ is sensitive to changes in illumination and sends signals to the pineal gland signaling the change between day and night. Photo-pigment commonly found in the lamprey, known as parapinopsin, is also found in the iguana, is photosensitive to UV light, and aids in the day-night signals.
Iguanas have developed a vegetarian lifestyle, foraging only for vegetation and foliage. To acquire, process, and digest plant material, herbivores must have a higher bite force relative to their size compared to carnivorous or omnivorous reptiles. The skull of the iguana has been modified resulting in a strong bite force and efficient processing of vegetation, according to one study.
To achieve this mechanically, herbivorous lizards (such as the iguana) have taller and wider skulls, shorter snouts, and larger bodies compared to carnivorous and omnivorous reptiles. Increasing the robustness of the skull allows for greater muscle presence and increases the skull’s ability to withstand stronger forces.
Furthermore, the teeth of the iguana are acrodontal, which means that their teeth sit on top of the jawbone surface and protrude upwards. The teeth themselves are small and toothed – designed to hold and shear food.
REPRESENTATION
Male iguanas, like other male examples of Squamata, have two hemispheres. During the incision, one hemipene will be inserted into the woman’s ventricle. A woman may store sperm from previous friends for several years to continue fertilizing her eggs in case she does not find a man in her territory when she is ready to lay again.
MATIO / COURSE
Iguanas tend to follow a promising or multilateral mating style during the dry season. Matching during the dry season ensures that their children will hatch during the wet or rainy season when food is more plentiful. Females control large territories where they make several nests. Males compete with each other for the females in an area and mark their territory gained with secreted pheromone from the femoral pores on the dorsal side of their hind legs. Male behavior during sexual competition includes bobbing head, stretching and pulling their leaf, fogging and biting women’s necks, and sometimes changing color. Once a female chooses a male, he bridles the female and holds her in place by biting on her shoulder, which sometimes leaves scars on women. After copulation, eggs are laid within several nests and allowed to hatch. This low level of parental intervention with their children makes iguanas an example of e-strategy reproduction. (Source: Wikipedia)