By sheer numbers:
* Insects: The sheer number of insect species and individuals on Earth is staggering. They occupy nearly every ecosystem and are incredibly resilient.
* Bacteria: The most abundant life form on Earth, bacteria are incredibly diverse and can thrive in nearly any environment. Their success is due to their rapid reproduction and adaptability.
By ecological impact:
* Humans: We have undeniably had a profound impact on the planet, both positive and negative. Our intelligence and adaptability have allowed us to dominate many ecosystems.
* Grazing Animals: Animals like cattle, sheep, and goats have shaped landscapes and influenced plant diversity through their grazing habits.
* Bees and other pollinators: These insects play a crucial role in plant reproduction, impacting entire ecosystems.
By longevity and resilience:
* Tardigrades (Water Bears): These microscopic animals are known for their incredible resilience. They can survive extreme temperatures, radiation, and even the vacuum of space.
* Sharks: Sharks have been around for millions of years and have adapted to many different environments. They are apex predators, indicating their successful survival strategies.
By evolutionary success:
* Crocodiles: These ancient reptiles have remained remarkably unchanged for millions of years, highlighting their successful evolutionary design.
* Cockroaches: They've survived numerous mass extinction events and continue to thrive in diverse environments. Their adaptability and resilience make them evolutionary success stories.
Ultimately, the "most successful" animal is subjective. It depends on what factors you consider most important. All species, from the smallest bacteria to the largest whales, have their own unique strengths and adaptations that have allowed them to thrive in their environments.