Loricifera

Tiny animals live in the sea.

They are very, very small. They wear a hard shell like armor. This shell protects their bodies.

These little friends hide in the sand. They live in the spaces between rocks. They stay stuck to the ground.

Some live very deep in the ocean. They live where there is no light. They even live where there is no air to breathe.

It is hard to find them. They were found only a long time ago.

Loricifera are very tiny animals that live in the sea.

Scientists call them corset animals. This is because they wear a hard shell. This shell is called a lorica. It is like a suit of armor. The lorica has six plates that go around their body. These animals live in the small spaces between ocean gravel. They attach themselves firmly to the ground. This is why it took a long time to find them. A scientist named R.M. Kristensen discovered them in 1983.

These animals have a head, a mouth, and a brain. They also have a neck and a trunk. Most species have both males and females. Some species are hermaphroditic. This means they have both male and female parts.

Some of these animals live in very strange places. Three species live at the bottom of the Mediterranean Sea. They live more than 3,000 meters deep. In this place, there is no light. There is also no oxygen to breathe. This is called an anoxic environment. These are the first multi-celled animals known to live there. They are less than one millimeter in size.

Loricifera are very tiny animals that live in the ocean.

Some people call them corset animals. This name comes from their special armor. This armor is called a lorica. It is a hard shell that protects their bodies. These animals are so small they are often microscopic. They live in the tiny spaces between sea gravel. They hold onto the ground very tightly. This makes them hard to find in the wild.

These small animals have a very organized body. They have a head with a mouth and a brain. A neck connects the head to the trunk. The trunk is surrounded by six plates. These plates make up the protective lorica. Each animal has nerves that connect to its brain. They do not have a circulatory system. They also do not have an endocrine system. This means they do not have certain types of internal tubes or organs.

Scientists only recently learned about these creatures. The first specimen was found in the 1970s. However, the group was not described until 1983. A scientist named R.M. Kristensen discovered them near Roscoff, France. They are among the newest groups of animals we know about. Some fossils might be from the late Cambrian period. This was a very long time ago. Scientists think they might come from larger, older animals.

There are 43 known species of Loricifera. We think there might be 100 more species. These animals can be found at all depths in the sea. They live in all latitudes around the world. Some species live in the L'Atalante basin. This is in the Mediterranean Sea. They live more than 3,000 meters deep. In this place, there is no light and no oxygen. This is called an anoxic environment.

Living in the deep sea is a hard job. The water there is a very salty brine. This brine is very dense and does not mix with other water. It also contains sulphide. Most animals need oxygen to live. These are the first multi-celled animals known to live without oxygen. They are less than one millimeter in size. They complete their whole life cycle in this dark place. It is a very strange way to live.

Loricifera are a phylum of microscopic marine animals. Their name comes from Latin words meaning "to bear a corselet." This refers to their unique protective armor. These tiny creatures live in ocean sediments. They inhabit the small spaces between marine gravel. They attach themselves very firmly to the ground. This strong attachment helped them stay hidden for a long time. Scientists only recently identified them as a distinct group of animals.

The body of a loriciferan is quite specialized. It consists of a head, a neck, and a trunk. The head contains the mouth and the brain. The neck region sits between the head and the trunk. The trunk is surrounded by six plates. These plates form the lorica, which is an external shell of encircling plicae. Each scalid on the animal is connected to the brain by individual nerves. Despite having a brain, they lack a circulatory system and an endocrine system. This means they do not have systems to pump blood or regulate hormones.

Loriciferans have complex ways of growing and reproducing. Their development is generally direct. However, some species produce Higgins larvae. These larvae look quite different from the adult animals. Most species are dioecious, meaning they have separate males and females. A few species are hermaphroditic. This means a single individual contains both male and female reproductive organs. Some pliciloricids even have very plastic life cycles. These cycles can include parthenogenetic reproduction, where offspring develop without fertilization.

The history of these animals is a relatively recent discovery for science. The first specimen was collected during the 1970s. However, the phylum was not officially described until 1983. R.M. Kristensen discovered them near Roscoff, France. They are among the most recently discovered animal groups in the world. While the group is new to science, fossils suggest they are very old. Some fossils have been dated to the late Cambrian period. Scientists believe they might be miniaturized descendants of larger organisms. One possible ancestor might resemble the Cambrian fossil Sirilorica. The 2017 discovery of Eolorica deadwoodensis may also help explain their history.

There are currently 43 described species of Loricifera. Scientists believe there may be approximately 100 more species waiting to be described. These animals are incredibly small, ranging from 100 micrometers to less than one millimeter. They are found at all depths and all latitudes in the ocean. They can live in many different types of sediment. This wide distribution shows how adaptable they can be to different marine environments.

Some loriciferans live in extreme conditions that most animals cannot survive. Three species live in the L'Atalante basin in the Mediterranean Sea. This basin is more than 3,000 meters deep. The environment there is anoxic, which means it has no oxygen. The animals live in a nearly salt-saturated brine. This brine is very dense, with a density greater than 1.2 g/cm3. Because it is so dense, it does not mix with the water above. This environment also contains a sulphide concentration of 2.9 mM. These are the first multicellular organisms known to spend their entire lives in anoxic conditions.

Scientists are still studying how loriciferans fit into the tree of life. For a long time, they were placed in a group called Vinctiplicata along with Priapulida. Together with Kinorhyncha, they form a taxon called Scalidophora. These three groups share features like a chitinous cuticle and rings of scalids. However, a 2015 study suggested they are most closely related to Panarthropoda. A 2022 study disagreed and placed them back in Scalidophora. More genetic testing will be needed to find their exact position within Ecdysozoa. This ongoing research helps us understand how all animal life is connected.