why axolotls have a certain dependece on water during their entire lifetime

Axolotls (Ambystoma mexicanum) are amphibians that retain their larval characteristics throughout their life, which is known as neoteny. This means they remain aquatic even into adulthood and have a high dependency on water throughout their lifespan for several reasons:

1. Respiratory Structure: Axolotls have gills and lung tissues. While they can respire through their lungs, their skin also plays a significant role in respiration, which requires a hydrated environment.

2. Habitat: They are native to the freshwater environments of Mexico, primarily in lakes with little to no wave action, where they are found in submerged vegetation close to the surface. Their entire life cycle occurs within this aquatic habitat.

3. Temperature Regulation: Being ectothermic, axolotls rely on the surrounding environment to regulate body temperature. Water helps maintain a stable and suitable temperature, as it has a higher heat capacity than air.

4. Metabolic Processes: Water is essential for axolotls' metabolic processes, such as digestion and excretion. They absorb nutrients and expel waste through their moist skin.

5. Reproduction: Axolotls reproduce in water and lay eggs, known as ova, in a gelatinous mass. The aquatic environment is necessary for successful fertilization, development, and hatching of the eggs.

6. Mobility and Locomotion: Axolotls have a streamlined body and lack limbs, which makes swimming their primary mode of locomotion. They rely on their fins to navigate their aquatic environment efficiently.

7. Sensory Perception: Their sensory organs, including touch, taste, and vision, are adapted for an aquatic lifestyle, which allows them to hunt prey and detect predators effectively.

8. Ectodermal Barrier: Water helps maintain the health of the axolotl's skin, which serves as a barrier against disease and infection. Dry conditions could compromise this barrier and lead to health issues.

9. Osmoregulation: Axolotls need to maintain osmotic balance, which is easier to achieve in water where they can exchange ions and maintain proper electrolyte concentrations.

10. Behavioral Patterns: Many behaviors of axolotls, such as feeding, mating, and territorial marking, are centered around their aquatic environment.

Given these biological and physiological requirements, axolotls have evolved to be highly specialized for an aquatic lifestyle, making it almost impossible for them to live without water for extended periods.