Aoxotl

Aoxolotl

The axolotl is a neotenic salamander, closely related to the Tiger Salamander. Larvae of this species fail to undergo metamorphosis, so the adults remain aquatic and gilled. It is alsocalled ajolote (which is also a common name for different types of salamander). The species originates from numerous lakes, such as Lake Xochimilco underlying Mexico City.] Axolotls are used extensivelyin scientific research due to their ability to regenerate limbs.



A sexually mature adult axolotl, at age 18–24 months, ranges in length from 15–45 cm (6–18 in), although a size close to 23 cm(9 in) is most common and greater than 30 cm (12 in) is rare. Axolotls possess features typical of salamander larvae, including external gills and a caudal fin extending from behind the head to thevent.[citation needed] Their heads are wide, and their eyes are lidless. Their limbs are underdeveloped and possess long, thin digits. Males are identified by their swollen cloacae lined with papillae,while females are noticeable for their wider bodies full of eggs. Three pairs of external gill stalks (rami) originate behind their heads and are used to move oxygenated water. The external gill ramiare lined with filaments (fimbriae) to increase surface area for gas exchange.[citation needed] Four gill slits lined with gill rakers are hidden underneath the external gills. Axolotls have barelyvisible vestigial teeth, which would have developed during metamorphosis. The primary method of feeding is by suction, during which their rakers interlock to close the gill slits. External gills areused for respiration, although buccal pumping (gulping air from the surface) may also be used in order to provide oxygen to their lungs. Axolotls have four different colours, two naturally occurringcolors and two mutants. The two naturally occurring colors are "wildtype" (varying shades of brown usually with spots) and melanoid (black). The two mutant colors are leucistic (pale pink with black...