On Earth The oldest animals: revealing the evolution and current status of prehistoric creatures

Introduction

The history of life on Earth spans billions of years, and many animals have lived on Earth for millions of years Even hundreds of millions of years old, they are the oldest animals we see today. These ancient creatures are not only important witnesses of the evolution of life on Earth, but also reveal the extraordinary adaptability of life to extreme environments and changes. However, with the changes in the modern environment, many ancient animals are facing threats to their survival and are either endangered or under protection. This article will give you a detailed introduction to some of the oldest animals on Earth and their protection levels.

1. Horseshoe Crab

Origin time: About 450 million years ago (Ordovician)
Habitat: Mainly distributed in North America and Coastal areas of Asia
Protection level: protected animals, some species are Near Threatened Species (NT)

Horseshoe crabs are a strangely shaped arthropod often called a "living fossil". The appearance of horseshoe crabs is almost the same as their prehistoric ancestors, and their blood contains a unique Copper-based compound - blue blood. This blue blood is widely used in medical testing and is a key component in detecting bacterial toxins. Although horseshoe crabs are widely studied, their habitat is seriously threatened due to coastal development, pollution and fishing.

Conservation status: The World Conservation Union (IUCN) lists some horseshoe crab species as "Near Threatened Species" , and strengthened the protection of its habitat, while calling for a reduction in the excessive extraction of horseshoe crab blood.

2. Coelacanth

Origin time: about 400 million years ago (Devonian period)
Habitat: coastal waters of the western Indian Ocean, South Africa, Indonesia, etc.
Protection level: Critically endangered species (CR)

The coelacanth was thought to have become extinct in the Cretaceous period about 65 million years ago, but in 1938, scientists rediscovered it in the waters off South Africa. It was discovered. Coelacanths are representatives of lobe-finned fish and are known as "living fossils". Their fin structure is similar to the limbs of tetrapods, revealing the evolutionary process of fish transitioning to land animals.

Conservation status: Due to its extremely small population, the coelacanth is listed as a "critically endangered species" by the IUCN. Global fishing activities, habitat destruction and climate change have brought tremendous survival pressure to the coelacanth.

3. Sponge

Origin: About 700 million years ago
Habitat: Oceans and freshwater areas around the world
Protection level: Generally no crisis, but the habitats of some species are threatened

Sponges are one of the earliest multicellular animals. As early as 700 million years ago, sponges lived in the oceans of the earth. Sponges seem simple. They have no organs or tissues and rely on cells in their bodies to absorb and filter nutrients. Although there are many sponge species, most are not under significant threat, but human activities have potential impacts on their habitats.

Conservation Status: Some sponge species live in fragile ecosystems such as coral reefs, so sponges in these areas are also threatened by habitat destruction, pollution and climate change.

4. Nautilus

Origin: About 500 million years ago (Cambrian period)
Habitat: Deep sea areas of the western Pacific and Indian Oceans
Protection level: Some species are Endangered species (EN)

Nautilus is a very ancient cephalopod that appeared on Earth as early as the Cambrian period 500 million years ago. Their shells have a unique spiral structure that helps them adjust their buoyancy in the depths of the ocean. Due to overfishing and commercial demand for its shells, the number of nautilus has declined dramatically.

Conservation status: Due to overfishing and commercial development, some species of nautilus have been listed as "endangered species". Some countries and regions have implemented protection measures for nautilus, restricting fishing and trade.

5. Crocodile

Origin: About 200 million years ago (Triassic)
Habitat: Rivers, lakes and wetlands in tropical and subtropical areas
Protection level: Some species are Critically Endangered (CR), and some species have recovered to **Least Concern (LC)** status

Crocodiles are one of the oldest reptiles on Earth, with ancestors dating back to the age of dinosaurs. Crocodiles evolved to become top predators in the water, with strong bite force and adaptability to the environment. Although some crocodile populations are stable, some crocodile species are facing survival crises due to habitat loss and illegal hunting.

Conservation status: For example, the Philippine crocodile (Critically Endangered Species) is extremely rare, while the American alligator has gradually recovered under strict protection and has been listed as Least Concern. Worldwide protection of crocodiles focuses on wetland and water protection and anti-poaching measures.

6. Sea Turtle

Origin: About 100 million years ago (Cretaceous)
Habitat: Warm waters around the world
Protection level: Most species are Endangered (EN) orCritically Endangered (CR)

Sea turtles are another ancient reptile whose ancestors can be traced back to the age of dinosaurs. Sea turtles have strong adaptability, can migrate long distances and adapt to a variety of marine environments. However, illegal fishing, plastic pollution, habitat destruction and climate change seriously threaten their survival.

Conservation Status: The World Conservation Union (IUCN) lists many sea turtles as "Endangered Species" or "Critically Endangered Species", such as leatherback and green turtles. Global protection of sea turtles has gradually increased, and their populations have been maintained by establishing protected areas, restricting fishing activities, and combating illegal trade.

7. Trilobite

Origin time: about 520 million years ago (Cambrian period)
Habitat: extinct, but widely present in prehistoric oceans
Protection level: extinct

Trilobite is one of the most representative animals that appeared during the Cambrian explosion. Their fossils are found all over the world and are important materials for paleontologists to study the evolution of early life. Although trilobites were widely distributed over more than 200 million years of Earth's evolutionary history, they eventually became extinct in the end-Permian mass extinction event about 250 million years ago.

Conclusion

The oldest animals on Earth are not only a symbol of natural wonders, they also represent the resilience of life and the wisdom of evolution. However, with the intensification of human activities, many ancient animals are facing unprecedented threats to their survival. To protect these precious "living fossils", we need to take more measures to maintain their habitats and reduce human interference and destruction. By protecting these ancient creatures, we are not only protecting the diversity of nature, but also preserving the precious heritage of the evolution of life on Earth.

Why are these animals called "living fossils"?

The term "living fossil" was first coined by Charles Darwin to describe fossils that have survived on Earth for millions or even hundreds of millions of years. , and their appearance and physiological structure have hardly changed significantly in the long evolutionary history. They not only represent the ancient life forms on Earth, but also provide scientists with important clues for studying life evolution, ecological adaptability and geological history. . The following is a detailed explanation of why these animals are called "living fossils".

1. Long evolutionary history

The reason why "living fossils" are called They are ancient because they appeared very early in the history of evolution, and some species can even be traced back to the geological period of hundreds of millions of years ago. These animals have survived the evolution of life on Earth and have passed through many This mass extinction event preserved the morphological characteristics of early Earth organisms, becoming a rare "living witness" in the biological world.

For example:

Horseshoe Crab: Its history can be traced back to < strong>Ordovician period 450 million years ago, an ancient relative of modern arthropods.
Coelacanth : Appeared in the Devonian period about 400 million years ago, it was originally thought to have become extinct along with the dinosaurs at the end of the Cretaceous period, but was rediscovered in the 20th century.
Nautilus: Their ancestors can be traced back to the Cambrian period 500 million years ago, and their unique spiral shell has hardly changed with time Changes occur.

The fact that these animals still exist today shows that they have a strong ability to survive such a long evolutionary process and can adapt to a variety of different environmental conditions.

2. High Conservation of Morphology and Characteristics

The so-called "morphological conservation" means that these animals have almost no Significant biological evolutionary changes have occurred. The appearance, structure and behavior of many living fossil animals are similar to their prehistoric ancestors, and fossils can even be directly compared with living species.

For example:

The body structure of the horseshoe crab is almost identical to that of earlier fossils, with three body parts (head and thorax, abdomen and tail) There is no obvious difference from its ancestors hundreds of millions of years ago.
The fin structure of the coelacanth has typical characteristics of lobe-finned fish and is considered to be the predecessor of tetrapods, but it has This evolutionary stagnation or "slow evolution" does not mean that these animals have not Instead of undergoing natural selection, they have found the most suitable form and ecological niche for their survival and do not need to make drastic changes to adapt to the existing living environment.
3. Special Ecology Adaptability
Many living fossil animals live in relatively closed and stable ecological environments, avoiding frequent environmental changes and competitive pressures. For example, in deep sea environments, coastal wetlands or extreme environments, biological communities Relatively stable, these ancient species can maintain their original form for a long time.
These species have specific ecological advantages in a relatively stable environment, reducing the competitive pressure with other species and avoiding the need for rapid evolution.
4. Escaped mass extinction events
There have been many mass extinction events on Earth, such as the Permian-Triassic mass extinction 250 million years ago and the Cretaceous-Tertiary extinction event 65 million years ago, and most species did not survive. However, living fossil animals have successfully avoided these extinction events through special survival methods and environmental adaptability.
This ability to survive makes them important subjects for studying geology and the evolution of life.
5. Important scientific research value of living fossils
Living fossil animals, due to their ancient and unique morphology and way of survival, provide scientists with direct evidence for studying the evolution of life in the early days of the Earth. By studying these animals, scientists can:
For example, the blood of horseshoe crabs contains a chemical called **LAL (Limulus Amebocyte Lysate)**, which can be used to detect bacterial contamination in drugs and vaccines and is still widely used in the biomedical field.
6. Threats to Survival and Conservation Status
Although living fossils have shown strong resilience in history, their habitats and living environments are seriously threatened by human activities in modern times. Overfishing, habitat destruction, climate change and pollution have all put tremendous pressure on the survival of these species.
Therefore, protecting these living fossils is not only to preserve biodiversity, but also to maintain the balance of the earth's ecosystem.

"Living fossils" are unique in nature. Their long evolutionary history, morphological conservation, special ecological adaptability, and ability to survive mass extinction events on Earth make them "living witnesses" of the evolution of life on Earth. By protecting these rare species, we can not only preserve the oldest life on Earth, but alsoWe can also learn about the forms of life and gain valuable scientific insights from them to explore the origin and evolution of life.

Coelacanth is listed as a "critically endangered species" due to deep-sea fishing activities, and only a small number of individuals remain in the world.
Horseshoe crab's habitat coastal development has seriously affected its population, and some species have also been listed as endangered.
Understand ancient ecosystems: By studying animals such as horseshoe crabs or coelacanths, we can get a glimpse of the earth's environment and ecological balance hundreds of millions of years ago.
Explore the details of evolution: The slow or stagnant evolution of living fossil animals provides valuable examples for exploring natural selection and adaptability.
Promote biotechnology: The blue blood of horseshoe crabs is used for medical testing, demonstrating the modern application potential of living fossil animals.
Animals such as coelacanths and horse crabs survived these mass extinctions, probably because they lived in relatively safe habitats such as the deep sea or coastlines.
Crocodile appeared 200 million years ago and survived the extinction of the dinosaurs to become one of the top predators we know today.
Coelacanths live in the deep sea, which has been in the deep sea for hundreds of millions of years. It is relatively stable and rarely affected by changes in the surface environment, which allows the coelacanth's body structure and lifestyle to be preserved.
Nautilus lives in the deep sea of the western Pacific and Indian Oceans, using its spiral shell to adjust buoyancy to adapt to the deep sea ecosystem, a feature that has remained almost unchanged since the Cambrian period.

The newest animal discovered on Earth

New species are constantly being discovered by scientists on Earth, especially in areas that have not been explored in depth, such as the deep sea, tropical rainforests and underground cave systems. Here are some representative new species discovered in recent years:

1. Glass frog (Hyalinobatrachium yaku)

Year of discovery: 2017
Habitat: Amazon rainforest, Ecuador
Characteristics: This frog is known for its transparent abdomen, which allows internal organs, especially the heart, to be clearly seen. Its unique appearance and the hidden nature of its habitat have kept it undiscovered for a long time.

2. Ophichthus kailashchandrai

Year of Discovery: 2021
Habitat: Oceans off the coast of India
Characteristics: ThisThe newly discovered moray eel is a carnivorous fish that lives in burrows on sandy bottoms. Scientists first documented the species while studying aquatic ecosystems off the eastern coast of India.

3. Tabbilbanosaurus humabonensis

Year of Discovery: 2020
Habitat: Philippines
Characteristics: A new species of freshwater crab that inhabits remote rivers and mountain systems in the Philippines. The crab gets its name from local culture and is characterized by its unique body structure and habitat.

4. Giant Sponge (Siphonophore)

Year of Discovery: 2020
Habitat: Deep Sea of Australia
Features: This giant sponge is over 45 meters long and is one of the longest marine organisms ever discovered. It is composed of thousands of small individuals that live together to form a structure similar to a single organism.

5. Pink flatworm (Bipalium kewense)

Year of discovery: 2019
Habitat: France
Characteristics: This flatworm is about 30 cm long and has a unique pink sheen. They are a predatory species that feeds mainly on other invertebrates.

6. Nocturnal Hunting Spider (Thomisus onustus)

Year of Discovery: 2018
Habitat: East Africa and Central America
Features: This spider has camouflage ability and can hide in flowers or leaves, waiting for prey to approach. Its discovery enriches our understanding of spider populations, especially in the nocturnal predation behavior.

7. Giant marine reptile (Bathynomus raksasa)

Year of discovery: 2020
Habitat: Deep sea in Indonesian waters
Characteristics: This is a giant isopod that looks like an enlarged caterpillar. They live in the deep sea and can reach a length of 30 cm. They are important scavengers in deep-sea ecosystems.

Conclusion

The discovery of these new species provides a new perspective for the study of biodiversity and further proves that there are still many biological communities on Earth that are not fully understood. The discovery of new species is not only an important progress in scientific research, but also a reminder to pay attention to protecting the natural environment, because many habitats where new species are discovered are facing threats from human activities, such as deforestation, pollution and climate change.

animal tags： ancient