do mexican salamanders are never need any water to survive during their entire lifetime

No, Mexican salamanders, such as the famous axolotl (Ambystoma mexicanum), do require water for certain aspects of their lifecycle, despite their ability to live outside of water as adults. Here are key points about their relationship with water:

1. Aquatic Larvae: As with most amphibians, Mexican salamanders start their lives as aquatic larvae. They hatch from eggs laid in water and must remain submerged until they undergo metamorphosis.

2. Metamorphosis: During this process, they develop lungs and can transition to a more terrestrial lifestyle. However, they still depend on a moist environment to prevent their skin from drying out, which is crucial for respiration and maintaining body moisture.

3. Breeding: Adult salamanders need to return to water to breed. The female lays eggs in a watery environment, ensuring the survival of the next generation.

4. Habitat: Even as adults, Mexican salamanders often prefer damp habitats close to water sources. This proximity allows them to maintain necessary skin moisture and to access water when needed for reproduction.

5. Hydration and Respiration: Their skin plays a vital role in both respiration and hydration. While they can absorb oxygen and some water through their skin, they cannot survive without access to moisture.

In conclusion, Mexican salamanders cannot survive their entire lifetime without any water. They might not need to be continuously submerged, but they require access to water or a moist environment for successful reproduction, hydration, and maintaining their skin's health.