Why learn about red coral?
“I am also called the red gold of the Mediterranean precisely because I live only here and I am of unparalleled beauty”
How do we recognize red coral
First of all, what is a coral?
IT'S AN ANIMAL! Or rather a group of animals called POLYPS that live in the same "house". I recommend polyps and not octopuses! (We'll talk about them in another article!)
What is a polyp?
The world of these animals is truly varied: they can be both small and large, both solitary and colonial…
We are now interested in the red coral polyps, so we will talk specifically about them in this article:
The polyps are transparent white, a few millimetres long and colonial.
They have a crown of 8 tentacles around their mouth.
The tentacles have stinging cells inside them (typical of the Cnidaria group to which all corals belong).
“They are our defensive weapon!”
They have a gastrovascular cavity that allows them to digest prey captured by the tentacles and brought to the mouth.
“It's our belly, let's say! A little simpler than yours!”
They have a protective skeleton made of calcite, which they produce themselves.
“We need it to hide in case of threat.”
Polyps are colonial and live close to each other, communicating through a dense network of channels called sarcosomes.
“We are one big family!”
Coral structure:
“You have to imagine coral as a condominium: we polyps are the tenants of the various apartments that gradually grow, reproduce and die, however making the condominium itself grow.”
The coral skeleton is produced by the polyps themselves and is mostly composed of crystallized calcium carbonate in the form of calcite.
Inside the skeleton there is a dense network of channels in which both nourishment and information passes between polyps within the colony.
The calcareous skeleton can grow considerably with concentric circles, and remains after the death of the animal: the importance of this fact is clear if we consider that coral reefs have formed over the millennia in exactly this way: by growing one on top of the other.
Where does red coral live?
It lives on the coasts of the eastern Atlantic Ocean in the Mediterranean Sea from 20 to 200 meters deep. It reaches the highest concentrations especially in the Tyrrhenian Sea, in habitats not too illuminated and water temperature around 18-20 ° C, with constant salinity and reduced currents.
“I love being in the shade, it will be easy to find myself among the ravines and caves of the steep cliffs while I eat without tiring myself!”
Only in rare exceptional cases can some colonies settle at low depths (4 m), finding ideal conditions as in the case of the caves of Porto Conte, Capo Caccia and Punta Giglio, in Sardinia.
“At these depths you can admire me, both snorkelers (with a little freediving) and scuba divers!”
What does red coral eat?
Red coral is a sessile animal, meaning it does not move and therefore eats small planktonic organisms transported by currents which it filters thanks to its ciliated tentacles.
The life of a coral
Corals have different ways of reproduction, each very strategic based on the animal's lifestyle. Let's see...
The red coral polyps are both male and female but divided into colonies, that is, there will be colonies composed only of females and only of males. They are not distinguishable from the outside.
They reproduce after 7-10 years of age, starting to mature the eggs between April and October.
Fertilization is internal and the larvae will remain in the mother's body for a long time before being released very close to the colony.
“We don’t want our children to move away from us, so they can settle in our colony and help grow it!”
The reproductive rate is very low, with an average of one larva per polyp being estimated.
The larva, settling on the bottom, will transform into a small polyp, immediately starting to produce calcium carbonate to anchor itself to the existing colony.
The growth of coral
Coral growth is estimated at 0.24-0.64 mm per year. To become 1 cm in diameter, coral takes 40-50 years and almost 20 years to grow 4 cm. After the first 3-4 years of irregular growth, coral follows an annual concentric growth that becomes useful to estimate the age of the animal itself.
“Think how delicate and slow we are to grow!”
Why is red coral so valuable and famous?
Red coral is composed of calcium carbonate, magnesium carbonate, calcium sulphate and iron oxide, which contributes to its colour. Furthermore, the whole is cemented by a protein part up to 3% of its weight; which contributes greatly both to the colour and to the strengthening of the mechanical properties of the skeleton itself. Its skeleton is in fact very hard and therefore excellent for being worked.
What distinguishes it from other corals is that once dead and out of the water it does not lose its color. The special composition of red coral will allow it to maintain this color forever.
Most tropical corals, on the other hand, live in symbiosis with small colored algae, which, once dead, remove their color, making them return to white, that is, the color of the original calcium carbonate (we will see this better in an article dedicated to them).
“This feature is our beauty and damnation”
The enemies of red coral
Natural Enemies
Red coral can be attacked by mollusks and small crustaceans that are fond of polyps. Environmental factors can also create serious problems for red coral.
The abnormal increase in temperature creates considerable stress for the polyps (accustomed to cool temperatures of 18-20°C) favoring diseases carried mainly by bacteria and fungi.
The increase in carbon dioxide in the water and therefore in acidity, makes it more difficult for the coral to mineralize, making it weaker.
The man
The enemy of red coral is man, it has been exploited since ancient times, not only for its use in jewelry but also as a medicine, currency, ornament, fertilizer and aphrodisiac.
Reduced to extinction, today it is minimally preserved thanks to the Marine Protected Areas that protect its survival and limit illegal fishing. In many Mediterranean areas it is no longer present and will not be able to reproduce for many years due to the complete destruction of the colonies.
There are other conservation projects such as grafting, attempts at regulated fishing and areas closed to fishing; but in fact at the moment the red coral in the Mediterranean is not protected sufficiently, too many economic interests are behind this magnificent animal, which will soon risk being just a vague memory…
The solution is often simpler than it may seem at Friendly Fins and we firmly believe that each of us can make a difference.
Come and discover with us how to be Friendly Fins towards our friend red coral! Click here!