can there are only terrestrial creatures existing on the world and without any aquatic creatures

In reality, it's impossible for Earth to be inhabited solely by terrestrial creatures without any aquatic life forms because:

1. Origin of Life: Life on Earth is believed to have originated in aquatic environments, such as the oceans, where conditions were favorable for the formation of essential biomolecules and the development of early life forms.

2. Evolutionary Continuity: Throughout Earth's history, aquatic environments have continuously supported a rich diversity of life. Many modern terrestrial organisms evolved from aquatic ancestors.

3. Ecological Interconnectedness: Terrestrial and aquatic ecosystems are interconnected through various processes like river flow, precipitation, and the movement of species between environments. This interconnectedness means that the complete absence of aquatic life would have profound and cascading effects on the entire biosphere.

4. Biological Requirements: All life requires water, and aquatic environments provide the necessary medium for many life forms to live and reproduce. Removing aquatic life would drastically alter Earth's water cycle and availability of fresh water, impacting all organisms.

5. Planetary Water Cycle: The water cycle, which includes evaporation from oceans, precipitation, and runoff, would be disrupted without aquatic systems to regulate these processes.

6. Genes and Genomes: Even terrestrial organisms have genetic material influenced by their aquatic ancestry. The genetic makeup of all life on Earth reflects an evolutionary history that includes aquatic organisms.

7. Adaptability: While many organisms are highly adaptable, the complete transition of all life to a terrestrial existence would require fundamental changes in their biology and ecology that are not feasible in the context of current biological understanding.

8. Ecosystem Services: Aquatic ecosystems provide vital services to the planet, such as carbon sequestration, oxygen production, and nutrient cycling. Without these services, the health and stability of Earth's ecosystems would be severely compromised.

The scenario of a world with only terrestrial creatures and no aquatic creatures is not only scientifically implausible but also ecologically disastrous. The coexistence of aquatic and terrestrial life forms is essential for maintaining the balance and health of our planet's ecosystems. Efforts should be focused on preserving and protecting both aquatic and terrestrial biodiversity for the benefit of all life on Earth.