Mesothelae

Some spiders are very special.

They are a group called Mesothelae. These spiders live in Asia. They have eight eyes. Their eyes sit on a small bump.

Most spiders make silk at the end of their bodies. These spiders make silk in the middle. They have eight silk tools. These tools are called spinnerets.

These spiders are very old. Some lived a long time ago. They have been around for millions of years. They are a very old group of spiders.

Mesothelae are a special group of spiders.

They are very old. Some lived over 300 million years ago. This was in a time called the Carboniferous. Most living Mesothelae live in Asia. You can find them in China and Japan. They also live in places like Thailand and Vietnam.

These spiders look different from other spiders. Most spiders make silk at the end of their bodies. Mesothelae make silk in the middle of their bodies. They use eight silk tools called spinnerets. These tools help them make silk. They also have two pairs of book lungs. Book lungs are parts that help them breathe.

Some of these spiders live in burrows. One kind of spider makes fishing lines. They put these lines near the entrance of their holes. Their long palps can look like extra legs. This can be a bit confusing! Scientists have studied these spiders for a long time. A man named Reginald Innes Pocock first named them in 1892. He saw how different they were from other spiders.

Mesothelae are a very special group of spiders.

They are thought to be the sister group to all other living spiders. This means they are a very old branch of the spider family tree. They still have many ancient features from their early ancestors. One such feature is a segmented abdomen. They also have two pairs of book lungs to help them breathe. Most spiders have their silk-making organs near the end of their bodies. Mesothelae are different because their spinnerets are located near the middle.

How these spiders work is quite fascinating. They have eight eyes that sit together on a small bump. Most members of this group have eight spinnerets. These spinnerets are arranged in four pairs. They use these tools to produce silk for their needs. Some spiders in the genus Liphistius live in burrows. They even make fishing lines near the entrance of their holes.

Their long palps, which are small appendages near the mouth, can look like extra legs. This can make them look quite different from other spiders you might see.

Scientists have been studying these spiders for a long time. Reginald Innes Pocock was the first to notice how unique they were. In 1892, he proposed the name Mesothelae. The name comes from Greek words meaning "middle" and "teat." This refers to the middle position of their spinning organs. Later, in 1923, Alexander Petrunkevitch suggested they were a separate group. Other scientists like W. S. Bristowe had different ideas in 1933. Eventually, researchers like Platnick and Gertsch argued for Pocock's view in 1976.

There are many important facts about where these spiders live. Today, you can find them in China and Japan. They also live in Southeast Asia in places like Laos, Malaysia, Myanmar, Thailand, and Vietnam. Some live on the island of Sumatra. The history of these spiders goes back a very long way. The oldest known Mesothelae lived over 300 million years ago. This was during a time called the Carboniferous period.

Many extinct families have also been found in the fossil record.

Learning about Mesothelae helps us understand how life has changed. They are like a living link to the ancient past. When you look at a modern spider, you are seeing a much newer version. Most spiders belong to the group called Opisthothelae. The Mesothelae show us what the very first spiders might have been like.

Even though they are small, they tell a huge story about Earth. They connect the tiny creatures in your garden to giants from millions of years ago.

Mesothelae is a suborder of spiders that provides a unique window into evolutionary history.

These spiders are considered the sister group to all other living spiders. This means they represent an ancient lineage that branched off very early. They are famous for retaining ancestral characters that most modern spiders have lost. One major feature is a segmented abdomen, also known as the opisthosoma. They also possess two pairs of book lungs, which are organs used for breathing. These traits help scientists understand how the earliest spiders were built.

The physical structure of Mesothelae is quite distinct from other arachnids. They are medium to large spiders that typically have eight eyes. These eyes are grouped together on a small bump called a tubercle. A defining characteristic is the position of their spinnerets, the organs that produce silk. In most spiders, these are located near the end of the abdomen. In Mesothelae, the spinnerets are located near the middle.

Most members of this group have eight spinnerets arranged in four pairs. They also have paraxial chelicerae, which are the mouthparts used for grasping. Additionally, they have two pairs of coxal glands located on their legs.

Taxonomy, or the science of naming and classifying life, has shifted for this group over time. In 1892, Reginald Innes Pocock first recognized how unique the genus Liphistius was. He realized it was more different from other spiders than they were from each other. He proposed the name Mesothelae, using Greek words meaning "middle" and "teat." This name directly describes the middle position of their spinning organs.

Later, in 1923, Alexander Petrunkevitch argued they should be a separate group. Other scientists like W. S. Bristowe suggested different groupings in 1933. However, in 1976, researchers Platnick and Gertsch argued for Pocock's original view. Modern molecular data, which looks at DNA, has since supported this classification.

The current classification of the living Mesothelae focuses on a single family called Liphistiidae. This family is divided into two distinct subfamilies. The first is Liphistiinae, which contains only the genus Liphistius. The second is Heptathelinae, which includes seven different genera.

These genera include Ganthela, Heptathela, Luthela, Qiongthela, Ryuthela, Songthela, and Vinathela. While some scientists previously argued for two separate families, the World Spider Catalog now accepts the single family approach. This organization helps researchers track the different evolutionary paths within the group.

Living Mesothelae are found in specific parts of the world. They are distributed throughout China and Japan. They also inhabit Southeast Asia, including Laos, Malaysia, Myanmar, Thailand, and Vietnam. Some species are also found on the island of Sumatra. The history of these spiders is incredibly deep. The oldest known Mesothelae fossils date back to the Carboniferous period.

This means they have existed for over 300 million years. This long history makes them a vital link to the ancient past.

There are several surprising facts about how these spiders live and appear. Some species of Liphistius build burrows in the ground. They create "fishing lines" in front of their burrow entrances to catch prey. This behavior is not seen in the Heptathelinae subfamily.

Some Mesothelae also have very long palps, which are appendages near the mouth. These palps can be so long that they look like an extra pair of legs. Furthermore, while it was once thought they lacked venom, recent studies show that many do have venom glands and ducts. This shows that even ancient traits can be more complex than they first appear.

Studying Mesothelae connects us to the broader history of arthropods. The fossil record includes many extinct families that were once thought to be Mesothelae. For example, the organism Megarachne was once classified this in this group. However, further study proved it was actually a species of eurypterid, an extinct arthropod.

Other extinct families like Arthrolycosidae and Pyritaraneidae have also been studied. Many recent fossils have been found in Burmese Amber from Myanmar. These fossils, dating to the Late Cretaceous, include genera like Cretaceothele and Burmathele. These discoveries help scientists map how spiders evolved alongside other ancient life forms.