1. What are the animals that don't have hearts?
Jellyfish: Jellyfish are transparent creatures in the ocean, they do not have a heart, brain, or blood. Jellyfish obtain oxygen and nutrients by diffusion while expelling waste.
Sponges: Sponges are one of the most primitive multicellular animals, they do not have a heart, blood vessels, and nervous system. Sponges live by filtering down tiny organisms and organic matter in seawater.
Flatworms: Flatworms are a class of parasites that do not have a heart, digestive tract, or respiratory system. Flatworms live by absorbing nutrients from their hosts from their bodies.
2. Survival strategies for cardiac animals
Diffusion respiration: Organisms like jellyfish exchange oxygen and nutrients directly with the environment through cells on the surface of the body, a way known as diffuse respiration.
Filter feeding: Sponges obtain nutrients by filtering on tiny organisms and organic matter in seawater, and their cells are able to break down these substances into usable nutrients.
Parasitic lifeParasitic organisms such as flatworms depend on nutrients provided by the host, and they absorb nutrients from the host through the surface of the body.
3. Adaptation and evolution of heartless animals
Animals without hearts occupy an important place in the history of biological evolution. Their existence shows that life can find its way to survive in an extremely diverse environment. These creatures are very adaptable and are able to survive in a variety of extreme environments. Their survival strategies and evolutionary process provide valuable clues for biologists to study the origin and evolution of life.
IV. Conclusion
Although animals without hearts make up only a small part of the biological kingdom, their presence undoubtedly enriches our understanding of the diversity of life. With their unique ways of survival and adaptability, these creatures show us the infinite possibilities of life. As we explore the mysteries of the biological world, let's not forget these heartless heroes, who together perform the magnificent chapters of life.