Clusters of cells began grouping together about 800 million years ago. This enabled greater life development, and eventually, these cells became the Earth’s first animals.

Scientists always believed sponges were the earliest animals, but recent evidence suggests that the comb jellyfish was actually the first. Many animals from prehistoric times became extinct, but these are five that still exist. 

1. Komodo Dragon

Dating back about four million years ago, the Komodo dragon is the largest lizard in the world. Weighing up to 300 pounds and reaching up to 10 feet in length, these powerful animals are incredibly strong. They have the ability to quickly swallow large pieces of meat thanks to a hinge that allows their jaw to open exceedingly wide.

It had previously been believed that Komodo dragons killed their prey with bacteria secreted in their mouths. But it is now known that they actually kill with venom. Their sharp teeth and venomous bite can kill an adult human. Able to eat up to 80 percent of their own body weight in one meal, they can also vomit up their stomach’s contents to lighten themselves if needing to flee.  

2. Horseshoe Crab

Dating back more than 300 million years, the horseshoe crab is not actually a crab — as they have no mandible or antennae. They are more closely related to spiders and scorpions. With an exoskeleton shaped like a horseshoe, they have long tails, which they use to steer themselves in the water and help flip themselves over if they end up on their backs. 

They have unusual blood that clots quickly when exposed to bacterial toxins. Researchers have used this blood to test drugs and vaccines. Due to the many uses for their rare blood, every year, thousands of horseshoe crabs are taken from their habitats, and (about one-third of) their blood is harvested for biomedical use. They are returned to the wild unharmed after the process.

3. Tapir

Many people have never heard of a tapir, even though they are the largest land mammal in South America. Also known as a living fossil, they have remained relatively unchanged for the past 20 million years. However, they are now endangered and are hunted by poachers for their meat and skins. 

Mostly nocturnal, tapirs are herbivores who eat up to 75 pounds of leaves, plants and fruit daily. While they are often said to resemble pigs or elephants, they are related to rhinos and horses. They love the water and will submerge themselves to cool off and dive to feed on aquatic plants.

4. Bactrian Camel

The Camelidae family dates back millions of years, and descendants still exist today. Bactrian camels were first domesticated between 5,000 and 6,000 years ago in Mongolia and China. They have been utilized by humans for travel in hot and dry desert climates, as camels can go long periods of time without food or water. 

They have been (and still are) a source of food — both meat and milk and their hair is used to create textiles. There is also the wild Bactrian camel, which is a different species. Also, dating back many thousands of years, they are endangered, with less than 1,000 in existence. 

Interestingly, they can drink salt water with a higher salt content than seawater, while domesticated Bactrian camels do not have the ability to do this. Scientists do not yet understand how this is possible. 

5. Jellyfish

Jellyfish have existed for over 500 million years, can be found worldwide, and include more than 2,000 types. Not actually fish, these gelatinous sea creatures are invertebrates, which have no backbone. With their dome-shaped body and trailing tentacles, they float through the water. However, they are not always aimlessly drifting — and can actually swim. By contracting and releasing their muscles, they propel themselves through the water.

They have a complete life cycle that includes five steps, starting with a fertilized egg and ending with an adult jellyfish, known as a medusa. The majority of jellyfish are clear, but some types of jellyfish are vibrant colors — and some are luminescent.

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