| rep / tile: any of a class (Reptilia) of air-breathing vertebrates that include the alligators and crocodiles, lizards, snakes, and turtles with a body usually covered with scales or bony plates The reptiles encompass a number of major groups technically distinguished from one another mostly by features of their skulls. More common distinctions rely on the overall body plans familiar to everyone: turtles and tortoises, lizards, snakes, and crocodiles. Additional small and little-known groups include the amphisbaenids (worm lizards), and the primitive lizard-like tuataras of New Zealand. Despite some pronounced differences in anatomy, reptiles are similar to each other in a number of ways. Most reptile species lay shelled eggs, which are resistant to drying. This feature separates them from the amphibians, which lay gelatinous eggs, Reptiles are unlike amphibians, however, in having a characteristically dry and scaled skin. Differences in scale number and distribution are often used by taxonomists to distinguish closely related reptile species. However, for the reptiles themselves, scales are important in forming a barrier to the environment, especially to water loss, a quality essential in hot dry habitats where reptiles are a dominant group. In contrast to fish scales, which are separate and detachable, reptile scales are thickened protrusions of a continuous skin, a feature that leads to their harvesting for various types of leather goods. Canada�s terrestrial reptiles comprise a total of forty seven species: 7 lizards, 15 turtles, and 27 snakes. In addition to these terrestrial reptiles four species of marine turtle are found in the Pacific and Atlantic Ocean Regions. Across Canada, Ontario has the most reptiles overall (25) with British Columbia and Quebec next at 16 species each. Significantly, many species from British Columbia species occur nowhere else in Canada. A relatively low number of reptiles compared to the U.S. and the rest of the world may be due to Canada�s relatively short summers which leave less time for reptile eggs to develop. Certainly, human fear of reptiles, especially snakes, contributes to mortality through deliberate killing. In addition, significant mortality occurs on roadways where reptiles bask to absorb heat from sun-warmed asphalt, or may simply be slow in crossing (e.g., turtles). Pesticides and contaminants also are thought to contribute to mortality with some concerns that contaminants concentrated in adults are passed to eggs causing deformity or death in young. Marine turtles face special threats that can include over-harvesting, entanglement in fishing gear, the commercial collection of their eggs, and the ingestion of sea trash. Yet for most reptiles, the biggest single threat is undoubtedly loss of suitable habitat or its fragmentation into �islands� cut off from other populations. Combined, these factors contribute to what is believed to be a global decline in the number of reptile species, an interesting, if sad, parallel to the situation for amphibians. |
