cnidarians
Cnidarians are a type of marine organism that includes approximately 9000 species. They live in all marine environments, including coral reefs and jellyfish. They all share many characteristics and are distinguished by the beauty of their shapes and the harmony of their colors. Cnidarians are considered carnivores, as they feed on plankton and small fish. They are also distinguished by their ability to replace the lost part of the body through a process called regeneration. As for the reproductive process, they reproduce in several ways, including sexual reproduction, asexual reproduction, and bisexual cnidarians.
Characteristics of cnidarians
Cnidarians are invertebrates and are characterized by many characteristics, including:
- Their bodies are symmetrical and centered around one central point.
- Its digestive system is in the form of a cavity containing the esophagus, stomach, and intestines, and it has only one opening for entering food and removing waste.
- The so-called stinging cells (in English: Cnidocytes) are used for food and self-defense, which is why they are called cnidarians.
Classification of cnidarians
Cnidarians are divided into four main types:
- Aquatic class: The class Hydrozoa is divided into six orders, the most famous of which are:
- The order Hydrida, which lives singly in fresh water, surrounded by 6 to 10 tentacles. It also reproduces through buds (asexual reproduction).
- The order Calyptoblastea lives in colonies interconnected with each other.
- The order Gymnoblastea lives in pinnate colonies surrounded by two types of tentacles: stomatal tentacles and stomatal tentacles.
- The order Siphonophora has many forms and lives in the form of colonies on the surface of the water.
- Class of calyxes: The Scyphozoa class includes several orders, including the Semaeostomeae, which is characterized by the presence of 8 to 16 sensory organs.
- Class of vases: All living organisms that fall under the class Anthozoa live in the seas, and this class includes only two orders:
- The order of fishes (in English: Alcyonaria) or Octocorallia, which has 8 feathery tentacles and lives in colonies.
- The order of flowering animals (in English: Zoantharia) or Hexacorallia, which live as individuals or colonies.
- Classification of cubes: The bodies of all organisms that fall under the Cubozoa class tend to be square in shape and have complex eyes.
