will terrestrial creatures completely replace aquatic creatures in the future

It's unlikely that terrestrial creatures could completely replace aquatic creatures. Here are a few reasons why:

1. Diverse Adaptations: Aquatic creatures have evolved unique adaptations for life in water, such as gills for breathing, fins for swimming, and streamlined bodies for movement. These adaptations make them well-suited to aquatic environments but not to terrestrial ones.

2. Different Ecological Roles: Aquatic and terrestrial creatures occupy different ecological roles and niches within their respective ecosystems. They interact with different resources, have different predators and prey, and influence their environments in distinct ways.

3. Unique Life Cycles: Many aquatic species have life cycles that are tightly linked to aquatic environments. For example, fish often lay eggs in water and their eggs hatch in water. Terrestrial species would struggle to replicate these aquatic life cycle stages.

4. Biochemical Differences: Aquatic organisms often have unique biochemical adaptations to their watery environments, such as the ability to osmoregulate to maintain salt balance. Terrestrial organisms have different biochemical needs and might not be able to meet these requirements in water.

5. Symbiotic Relationships: Many aquatic species have developed intricate symbiotic relationships with other aquatic organisms. For example, coral reefs host a diverse array of species in a mutually beneficial relationship. Terrestrial species lack these specialized relationships and may not be able to form them in water.

6. Evolutionary Distance: Aquatic and terrestrial species are separated by millions of years of evolution. While there are some transitional species like semi-aquatic mammals, these are exceptions and not the norm. The vast majority of aquatic and terrestrial species are distinct groups that have evolved along separate paths.

7. Environmental Impact: Replacing aquatic creatures with terrestrial ones would fundamentally alter aquatic ecosystems. This could lead to a loss of biodiversity, disruption of food webs, and degradation of water quality, with cascading effects throughout the ecosystem.

In short, while there may be some overlap between aquatic and terrestrial species, they are largely distinct groups with unique adaptations to their respective environments. The idea of one group completely replacing the other is unlikely due to these differences and the potential ecological consequences of such a transition. Aquatic and terrestrial ecosystems are interconnected and interdependent, and both groups of species play vital roles in maintaining the health and functioning of our planet.