Axolotl

Axolotl is a well-known species of salamander known by the scientific name Ambystoma mexicanum. They are an endangered species as the growth of Mexico City destroyed their natural habitat. However, they are popular among pet lovers for their exotic smooth and colorful skin, external gill, small eyes, and face with a resemblance of human. Their regenerating abilities are also studied thoroughly in labs.

Anatomy
The length of Axolotls ranges from 15 cm to 45 cm, but most of them are around 23 cm, and it is hard to find Axolotls over 30 cm. Axolotls has three pairs of specialized external gills extended on the side of head. Little branches of external gills increase the surface area that contacts water. This increase speeds up the exchange of oxygen between gills and oxygenated water. 

Axolotls have undeveloped limbs with long, thin digits. Axolotls do not have eyelids. Their skins are smooth and moist, and they do not have scales. Axolotls usually have one of four skin colors,two natural colors and two mutant ones. Natural colors are wildtype, which is a shaded brown with lots of spots, and melanoid, which is black. Two mutant colors are leucistic, pale pink skin with black eyes, and albino, which is golden, tan or pink with pink eyes. Axolotls have amazing regeneration ability that if a young axolotl loses its foot, it will be regenerated in few weeks.

Reproduction
Axolotls reproduce around age of 6 months to several years when they are sexually mature. The time that axolotls take to be sexually mature varies usually because of environment conditions: temperature and the availability of food,for example. Reproduction usually occurs in spring, when the water temperature is high.

Male axolotls start the reproduction by swimming around and laying 5 to 30 spermatophores, packets of sperms. Females come around and pick up some of these spermatophores in their cloaca, and allow the sperms to fertilize eggs inside her. Fertilized eggs are laid on the leaves of water plants or rocks. These fertilized eggs are hatch after about 17 days. 

Ecology
Axolotls are indigenous to two lakes in central Mexico: Lake Xochimilco and Lake Chalco. These native habitats are destroyed as the Mexico City's population and economy grow. Lake Chalco has been drained in order to prevent periodic flood in the area. Lake Xochimilco also has lost its natural and wild features as it is used as canals. Losing their natural habitats, axolotls are categorized as an endangered species by CITES, and crticially endangered in the wild by IUCN. 

Axolotls are carnivorous species, eating insects, worms, and small fish. They detect preys with olfactory sensors. When they detect a prey, they use the vacuum power to catch it.

Other
Back in history, axolotls were a great portion of diet in Aztec civilization. Nowadays, they are still sold as food in Mexico, but they are not a staple for Mexican people. Axolotls are usually sold as pets in current days, getting attention from pet lovers for their smooth and beautiful color of their skin. Also their face resembles that of humans when they smile, which is one of the main reason that people have them as pets. The appearance of axolotls also gave an inspiration to a Japanese cartoonist, and Wooper, one of the characters in the famous cartoon, "Pokemon," is drawn based on the appearance of axolotls. Axolotls are also used in labs to study their healing abilities.