Coelenterates are one of the oldest living creatures on Earth. They appeared at a time when life was beginning on the planet. Now they have acquired a variety of forms.
For humans, coelenterates are important — construction materials are extracted from dead calcareous parts of corals. Some types of coral are used for jewelry. Coral reefs serve as a refuge for fish and often become a real work of art, which divers descend to see.
The most beautiful and unusual representatives of radial animals are jellyfish. They impress not only with their appearance but also with their size.
The article presents 10 of the most interesting facts about coelenterates.
1. Cyanea capillata – the largest representative of the group
This jellyfish has many names: Arctic cyanea, capillata cyanea, hairy, or lion’s mane, but all mean the largest representative of the coelenterate group. The tentacles reach a length of almost 40 meters, and the dome’s diameter grows to 2.5 meters. These parameters make the Arctic cyanea the longest animal on the planet.
Cyanea capillata has several species, but the exact number is still unknown, and scientists are actively debating. Its size can be compared to the blue whale, considered the longest creature on the planet. Its length can reach 30 meters, so it is very fair that Cyanea capillata claims the title of the longest animal.
It lives in cold waters and can be found on the coasts of Australia, but the maximum number of them live in the Pacific and Atlantic Oceans. It reaches its maximum length in the Arctic; its growth does not exceed the average in warm waters.
2. Zoantaria Palythoa – the most dangerous coral
Coral has palytoxin, one of the most toxic substances found in the wild. Palitoxin is produced due to the symbiosis of zoanatry with microalgae-dinoflagellates. Many living creatures that feed on this coelenterate or are in symbiosis with them can also accumulate this dangerous substance.
Since ancient times, the aborigines of Tahiti have used coral to make poisonous and deadly weapons. Palytoxin was discovered only in 1971, even though corals have existed for several thousand years. This substance is also the most complex chemical compound in nature. It is toxic to all warm-blooded animals, especially rats, monkeys, rabbits, and humans – the strongest poison of non-protein nature.
3. Corals are vital to sunlight
Anyone who went diving or watched programs about the unique underwater world probably noticed unusual corals. They make a real fairy tale out of the depths of the sea. Best of all, coral reefs develop at a depth of up to 50 meters, as they are vital for sunlight, so the water should be clear. Even though the sun’s rays can penetrate to a depth of 180 meters, corals grow poorly there.
This is the most diverse ecosystem on the planet, which occupies only 0.1% of the surface of the world’s oceans. The most important physiological and biochemical processes are associated with photosynthesis, so they are developed in shallow water.
4. Hydras are considered immortal
Hydra is an amazing little creature that has gained popularity due to its unusual property. If you cut a hydra into several parts, then. As a result, these parts turn into new living creatures. Therefore, it is called immortal. The whole organism can be restored from individual small pieces of the body (less than 1/100 of the volume), from pieces of tentacles, and a suspension of cells. This phenomenon is called biological immortality in science.
In simple words, such an animal does not die of old age but can only die from an external factor. Because the creature can still be killed, it cannot be said that the hydra has immortality.
5. The tentacles of the furrowed Anemonia have a diameter of 1.5 m
One species of coelenterate broke the record for the diameter of tentacles. The tentacles of the furrowed Anemonia, which wriggle like a snake, reach a diameter of 1.5 meters. By the way, this species gets along well in aquariums. These purposes can be safely delivered even from the most remote seas.
You can see it in the Mediterranean Sea or the Atlantic Ocean. This marine animal is eaten in southwestern Spain and is called the “little sea nettle,” because of its disgusting properties during cooking.
6. Asexual and sexual reproduction mechanism
Coelenterates have a mostly asexual mechanism of reproduction — budding. But they can also reproduce sexually, most often in the fall. Coelenterates can alternate the mechanism of reproduction: one generation uses budding and the other-sexual reproduction.
Polyps give rise to the next generation of polyps and jellyfish, which in turn leave offspring through the sexual mechanism.
7. There are no specialized respiratory, circulatory, or excretory organs
The body of coelenterates resembles a sac, which consists of an inner and outer layer. Between them is connective tissue. The endoderm forms an intestinal cavity that connects to a single opening. This is all that can be said about the structure of this animal.
Coelenterates do not have specialized organs, and a single opening performs oral and anal functions simultaneously. They also have no blood circulation or discharge.
8. Radial symmetry of creatures
The location of organ systems and body parts differs in all living organisms. Coelenterates have a radial system. It has a certain geometric order. The main elements are the center, line, and plane. This is typical of marine inhabitants because the body’s response is the same everywhere due to the same habitat.
The symmetry of coelenterates may differ depending on the angle of inclination of the animal. Thus, we can define 4-,6 -, and 8-ray symmetry.
9. One of the oldest living things on Earth
Anyone who studies the history of life on Earth probably knows that coelenterates are one of the oldest animals on our planet. Evolution on Earth began with the appearance of the first living being; it happened almost 4 billion years ago and continues to this day.
Scientists were able to prove that coelenterates lived in the Precambrian. Little is known about the Cryptozoic period, but it was then that the first signs of life appeared, and this period meant a lot for evolution as a whole.
10. There are two modern types cnidarians and ctenophores
Multicellular animals are divided into two modern types: scallops and ctenophores. Only marine life is considered a rattler. Their peculiarity is the presence of stinging cells, which is why the name came from. They are also called Cnidarians. To date, about 11,000 species have been found.
Ctenophores also include marine life, but their peculiarity is the presence of cilia or a special comb. These two types of animals are very similar to each other.