Why are corals called floral animals? Are corals animals or plants? Or even both? Let’s get to the bottom of these questions. To do this, we need to know how a coral is built and what distinguishes animals from plants.
The coral belongs to the group of cnidarians. The body structure is a hollow skeletal cylinder, which has a mouth opening, called polyp, by which the tentacles are located. The tentacles are used to ingest plankton as food on the one hand, and on the other hand, they are also used for defense.
By the number of tentacles it can be recognized to which subgroup the coral belongs. The polyp with 8 (only eight) tentacles belongs to the Octocorallia group also known as soft coral.
The polyp with 6 or a multiple of 6 tentacles (12, 18, 24, etc.) belongs to the group Hexacorallia from named as stone coral.
An individual polyp can range from one to several millimeters in diameter. Almost all coral polyps form a colony.
What distinguishes animals from plants?
An animal eats and moves around. A plant does not eat, needs only soil, water, and air to survive, and does not move away.
These differences are too imprecise and are not sufficient to determine with certainty the assignment whether animal or plant.
It was not until the development of the microscope, in the early 17th century, that it became possible for scientists to see cells, to recognize and understand their structure and peculiarities.
The size of a cell usually varies from one to thirty micrometers.
One micrometer is equal to one thousandth of a millimeter or 0.0001 millimeter
The cells of more highly developed animals are larger and can be as small as 0.1mm.
It was not until the development of the electron microscope, in 1930, that science was able to examine cells in even greater detail and make visible what was still unknown.
All living things, animal and plant, are made of cells.
The cell, in the biological sense, is the smallest living unit of an organism. Not all cells are the same. The cell of animals and plants, can be thought of as a sphere filled with fluid. Inside this sphere are the nucleus and other units, such as organelles.
Depending on the type of living thing, cells have different structures.
So animals and plants can be distinguished by the structure of the cell.Plant cells have a cell wall, animal cells have no cell wall.
When the tentacles of the coral were examined, they were found to be composed of cells that could be assigned to animals.
This indicated that the coral should be assigned to the animals.
It was unclear what the reason is that the coral is able to do exactly what is the characteristics of plants, to convert light into energy, known and explained as the process of photosynthesis.
When coral polyps were examined in microscopic detail, it was found that the coral lives in a symbiotic relationship with zooxanthellae.
Skizze des Chloroplasts von Von Kelvinsong Quelle: https://de.wikipedia.org/wiki/Chloroplast
Skizze Zellen: https://www.digitalefolien.de/biologie/pflanzen/aufbau/zell.html