Reptiles lizards

Vertebrata includes hagfish, lampreys, sharks, rays, skates, ray-finned fish, coelacanths, lungfish, frogs, toads, salamanders, manunals, and reptiles (lizards, snakes, turtles, alligators, erocodUes, and birds). 

Defensive Compounds. The developmental stages of fireflies are poisonous due to the presence of steroidal pyrones called lucibufagins. Recently it became evident that exotic reptiles and amphibians from habitats without the poisonous fireflies, e.g. the Australian lizard Pogona, are killed immediately if they ingest just one firefly. 

FIGURE 5.8 Location of the vomeronasal organ (VNO, cross-hatched) in amphibians and reptiles. Arrows show air entering through the external nares at top and exiting through the choanae at bottom. From there, VNO receives air with odors. N nasal cavity. In lizard, VNO receives stimuli from mouth cavity below, with help from tongue. (Redrawn after Romer, 1959.)... 

Reptiles advertise their territories mostly by visual displays, but some olfactory marking may occur. For instance, western fence lizards, Sceleporis sp., of North America deposit fecal boli in prime basking sites, which are important... 

Reptiles like the snake and the lizard cannot regulate their body temperature, and adopt the temperature of their environment (i.e., they are poikilother-mic) - so they cannot survive extremes which put their body cells, and particularly their enzyme systems, at risk. By contrast, we can shiver or sweat to increase or reduce our core temperature, and so human beings can function effectively in a much wider range of temperature than can reptiles. What has this to do with drugs and other ingested chemicals In just the same way as we mammals have evolved to be relatively independent of environmental temperature so we also have developed a system of screening and filtering out chemical substances that present themselves to us in our diet and from other sources. 

Terrestrial reptiles also avoid considerable evaporation by being quiescent in burrows much of the time. Also, their skin is more impermeable than that of amphibians, although water is still lost in expired air. Hydrated lizards have low urine filtration rate (urine always hypotonic), and may... 

Reptiles are divided into four orders. The order Crocodylia includes crocodiles, alligators, and their relatives. The order Testudines includes the turdes and tortoises. The order Rhynchocephalia is represented by only two species, the tuataras of New Zealand. The largest order by far is the Squamata, which has over 7000 species of lizards, snakes, and their relatives. 

Metamorphosis has also been extensively studied in amphibians, a class of vertebrates which includes frogs, toads, and salamanders. Amphibian means dual (amphi ) life form (-bian) and refers to the typical life history of these animals, in which an aquatic larva metamorphoses into a terrestrial adult. The reptiles, such as turtles, lizards, and snakes, is another class of vertebrates whose species superficially resemble adult amphibians, but do not undergo metamorphosis. 

Reptiles are not usually associated with marine environments. In fact, of the 6,000 known species of reptiles, only about 1 percent inhabits the sea. Members of this select group include lizards, crocodiles, turtles, and snakes. Each of these organisms shares many of the same anatomical structures that are found in all reptiles They are cold-blooded, air-breathing, scaled animals that reproduce by internal fertilization. Yet, to live in salt water, this subgroup has evolved some special adaptations not seen in terrestrial reptiles. 

Vertebrates who live along the oceans shores include several species of fish, birds, and mammals and one species of reptiles. The only shore reptile is the marine iguana, a lizard found only on the Galapagos Islands. Unlike terrestrial iguanas, this species is adapted to life on the edge of the sea where it feeds on intertidal algae. To dine, the lizard must dive into cold, wave-tossed ocean water and scrape the microscopic plants from rocks. Intertidal life is rough for this reptile, but its adaptations have enabled it to be successful in an environment in which no other reptile can survive. 

Feeding commences after mating. Their diet is mostly small mammals and reptiles, particularly mice, voles and common lizards. They also take fledgling birds, and occasionally frogs. Vipers can swim well, but this is generally a much rarer... 

T. zimbabwensis or T. papuae human infection are available. However, one human trichinellosis outbreak due to consumption of reptile meat from a monitor lizard Varams nebulosus) has been documented in Thailand (Pozio 2007a). In addition, a 10% prevalence of serum mti-Trichinella IgG antibody was detected in the inhabitants of Morehead District of Papua New Guinea, where wild-pig meat, potentially infected with T. papuae, represents the main source of protein (Owen et al. 2005 Pozio and Zarlenga 2005). Although persons reported muscular or joint pain, the infection was apparently no severe, suggesting that seropositive people are exposed to recurring infections with very few larvae (Owen et al. 2005). 

In an effort to test the system and to generate preliminary data on the toxicity of munition compounds to reptiles, acute oral toxicity studies on TNT, DNT, and RDX were conducted using Western fence lizards (S. occidentalis) [60], All three compounds were administered via gavage in a com oil vehicle. Table 7.1 shows the median lethal dose (LD50) for lizards orally exposed to these common munition compounds. Based on these data, RDX is relatively more toxic to fence lizards than TNT and DNT. Males appear more sensitive to RDX than females, while females are more sensitive to DNT than males, although generalizations on the relative sensitivity of males and females should be approached with caution. Overall, these data suggest that RDX is most toxic, and DNT and TNT are less toxic. 

Talent LG et al., Evaluation of western fence lizards (Sceloporus occidentalis) and eastern fence lizards (Sceloporus undulatus) as laboratory reptile models for toxicological investigations, Environ. Toxicol. Chem., 21, 899, 2002. 

Avoid direct or even indirect contact between reptiles (turtles, iguanas, other lizards, snakes) and infants or immunocompromised persons. 

---