Discover Italia ti invita a esplorare le meraviglie del pianeta blu
The first, the Sphyraena viridensis, is in all respects an “alien”, considering that its area oforigin is the north-eastern Atlantic Ocean, although, in addition to being known as the yellowmouth, it is also known as the Mediterranean Barracuda, the sea in which it has spread only a decade or so, as a result of rising temperatures.
They are small marine animals. Extremely small. And yet, they have an enormous and unparalleled importance in the complex and delicate ecological balances of the oceans. And therefore of the entire planet, considering that the blue expanse occupies over 70 percent of its surface.
It is the largest. But also the most harmless among jellyfish. The Barrel Jellyfish,
A formidable jumper, its brightly colored livery makes it stand out on the blue surface of the sea.
It is a fish. But with such a particular shape that it is difficult to classify it as a fish.
Among the inhabitants of the sea, it is one of the most popular subjects for those who photograph the beauties of the blue planet. And it is one of the symbols of the Mediterranean, although it is also present in the Atlantic Ocean. Belonging to the Serranidae family, which has about eighty species, eight of which are at home in the Mare Nostrum, the Dusky Grouper (Epinephelus marginatus) is certainly the most widespread and familiar. Among the largest bony fish in the Mediterranean, carnivorous and formidable predator at the top of the food chain, it plays a delicate and fundamental role in the ecological balance of the sea. Therefore, the progressive decrease found throughout the Mediterranean basin represents a serious problem, confirmed by the "vulnerability" assessment that the IUCN, the International Union for Conservation of Nature, has attributed to the species.
Groupers are territorial animals, living alone in their burrows among the rocks, but it is not uncommon to find them nesting among the sandy seabeds where Posidonia and Zostera grow. It prefers to live between 10 and 200 meters, but some specimens have been found even at greater depths. It hunts its prey during the day, mostly cephalopods and fish. It is not aggressive with species that are not among its prey, but tends to be aggressive with marine animals that share its territory and with other male groupers.
The large head is a peculiarity of groupers. Like the large mouth, with a mandible protruding from the maxilla, equipped with canines and other teeth, inclined inwards, some mobile and depressible, functional to the variety of prey it feeds on. The body is robust. The color can vary during the breeding season and in particular situations, such as when the animal is scared. In general, the back has a coloration between dark brown and dark red with numerous gray or yellowish spots, distributed everywhere even on the head; the belly is lighter, tending towards yellow. The odd fins are dark brown with a white edge at the tip, the pelvic and pectoral fins are dark, yellowish at the base. The tail, with a rounded fan shape, is streaked with white. It has spines on the long dorsal fin and on the anal fin. It can reach one meter and twenty in length and an average weight of sixty kilos in the male. The female is smaller.
Groupers can live up to fifty years. They are protogynous hermaphrodites, meaning they are born female and reach sexual maturity at 5 years of age. Then, around 12 years of age, and in any case between 10 and 15, they become male. While this is the general “rule,” there are also particular situations, mostly related to the needs of the species, in which the sex change does not occur.
In the Mediterranean, it is during the summer season that grouper specimens temporarily give up solitary life and gather together for reproduction with other similar ones, in sites at a depth of between 15 and 30 meters. The species has been subject to excessive hunting, especially in the last century, which has led to its reduction everywhere, even making it rare in some parts of the Mediterranean where it was once very widespread. Since the adults and larger specimens, therefore the males, are preferred as prey, imbalances have been created in the population between males and females, thus interfering with the reproductive capacity of the species. But also the pollution of the sea and increasingly the effects of global warming represent threats to groupers. In recent decades, various protection projects have been dedicated to them and in any case in the Marine Protected Areas active protection is starting to bear fruit. Considered an endangered species in the Mediterranean and in the rest of the world, it is protected by the Bern and Barcelona Conventions. And it is a precious indicator of the ecological balance of the sea: where there are groupers, it means that the food chain works, that there is biological variety, that protection is effective.
The Italian Marine Protected Areas also include the rarer Red Grouper (Mycteroperca rubra), reddish brown, darker on the back and much less on the belly, with dark lines and white spots on the sides, and the Golden Grouper (Epinephelus costae), also known as the ductus, two-coloured with a brown and beige body with a characteristic ovoid golden spot near the gill cover and very visible bands on the sides.
It is the natural “secret” of the red-pink color of flamingos.
A tiny animal of that same color, whose small size is inversely proportional to its presence on earth. In fact, the maximum length of an adult specimen of Artemia salina, the species that appeared on the planet in the Triassic, is just one centimeter, therefore a good one hundred million years ago, when dinosaurs also inhabited the planet. And since then, the tiny crustacean, the only representative of the Artemia genus and the Artemiidae family, has retained its main morphological characteristics, thanks to which it has had the ability to adapt to the most varied and extreme environmental conditions and to become a true model of resilience in the animal kingdom.
Artemia lives in every part of the globe, so it is a so-called cosmopolitan species, except in the oceans, and survives between 5 and 40 degrees in almost fresh to very salty waters, having as its habitat the more or less brackish coastal ponds and salt marshes, from which the epithet of its scientific name "salina" derives. The safest places, since the high salinity keeps away most of the potential predators. But more commonly, due to its appearance, it is known as sea-monkey.
The body features include the head, with three eyes and four antennae; the thorax with eleven limbs and a series of lamellae, which allow it to breathe, but also to get rid of excess salt introduced with the water from which it filters nutrients; and the almost transparent abdomen from which the intestine can be seen. The species presents a notable sexual dimorphism, since the males have a larger jaw. Another characteristic of the species, to facilitate nutrition through water, is swimming with the back facing downwards.
Since they are extremely small, they feed on bacteria, phytoplankton and all possible nutrients that do not exceed the size of 50 microns. And it is precisely from food that their particular pink and orange color comes, in fact the small green algae Dunaliella salina (which also lives in the same habitats with a high percentage of salinity) that they feed on, produces beta-carotene. The substance that then ends up in the diet of flamingos that, in turn, feed on Artemia. The more or less pronounced pink or red-orange color of the waders that populate the same brackish environments depends, in fact, on the percentage of Artemia present in their diet: the more crustaceans they swallow, the more brightly colored their legs, beak and plumage are, making them unmistakable in their beauty.
Artemia crustaceans have a lifespan of around seven hundred days, during which they go through various larval stages, before becoming adults and, therefore, entering the reproductive stage, which is another highly characteristic element of the species. Artemia reproduces sexually at temperatures between 20 and 35 degrees and it is necessary for there to be water in the ponds in which it lives. When this condition is lacking, due to evaporation of the water and in periods of prolonged drought, in dry ponds Artemia reproduces by parthenogenesis, laying cysts, or eggs with a particularly resistant shell, which remain "suspended" even for long periods (cryptobiosis), even up to ten years, ready to hatch as soon as the environmental conditions are favorable again. From the eggs, larvae called nauplii of a few millimeters are born, which draw nourishment from the yolk sac and, therefore, can remain alive without the supply of other nutrients for two or three days after hatching. Nauplii are prey for numerous species of marine animals, which carry out a considerable selection of organisms before they develop into the subsequent larval stages. Furthermore, when a reproductive emergency occurs, for various reasons, it can also reproduce asexually.
The versatility of this species, its enormous capacity for resilience in adapting to the most varied environmental conditions in which it lives, even the most extreme and least favourable, has made it the totem animal of the aboriginal populations of Australia.
Its common name in several languages including Italian associates it with the Gorgons. And one of them, Euryale, is evoked by the order of the Euryales to which it belongs. But it is certainly not a monster, as the mythological figures with hair formed by snakes were considered. Quite the opposite.
The Gorgon star or Astrospartus mediterraneus is a marine animal of astonishing beauty. A living lace, when at night it completely opens its spectacular tentacles to get food. And it is in that form that the reference 
to the Gorgons appears evident. And the origin of its scientific name from aster, star, and spartus, shrub, for the numerous ramifications of its arms. Instead, during the day, when it is not busy feeding, and folds its tentacles, it forms a sort of ball or basket that justifies the name in English of basket star.
The Astrospartus lives at depths between 30 and 800 meters in the western Mediterranean and the North Atlantic, along the coasts of Spain and West Africa up to Senegal. Widely distributed off the African coast of the Mediterranean, it is less so around Italy, where, although it is present from the sea of Sicily to those of Tuscany and Sardinia, it is quite rare to meet it. Since it is a photophobic animal, which avoids light, it is active at night and prefers poorly lit and deep sites.
With its light color, which can vary between gray and yellow with pink hues, it stands out against the dark red of the red gorgonian (Paramuricea clavata), also a filter-feeding animal, on which it prefers to settle, but it also does so on the white gorgonian (Eucinella singularis) and on various species of sponges. To attach itself to the animals it hosts, it uses small hooks present at the ends of the numerous branches of its ten, thin tentacles. They all start from the central body, formed by a disk with a maximum diameter of around 8 centimeters, in which the five symmetrically arranged sectors can be distinguished. They are the distinctive element of the Echinoderms, of which the Astrospartus is also a part.
The body has a mouth, to which the tentacles bring food, as they capture it by filtering the plankton present in the water column, but also by wrapping and "imprisoning" small fish and marine animals. The width of the crown of tentacles with all their ramifications, when fully unfolded, can reach 80 centimeters in diameter, thus tenfold the size of the central body and serves to procure as much food as possible. Then, when the need to feed is satisfied, the scenic offshoots are folded one after the other, until they form the basket shape typical of the resting phase of the beautiful sea gorgon.
He never gives them up. And every time he moves to a larger shell, he takes care to prepare an adequate accommodation in the new home also for his faithful traveling companions. And life companions. The only ones with whom he agrees to share the “domestic” space in which he notoriously does not like intrusions, not even from his peers.
It is no coincidence that, together with the recovery shell adapted from time to time to the new measurements of its growing body, the Paguro Bernardo carries with it that nickname of “hermit” borrowed from its solitary existence. The only exceptions are the anemones anchored on its shell, belonging to the species Calliactis parasinica, which for this consolidated symbiosis is naturally associated with the Pagurus bernhardus.
Community life, the result of a long and complex adaptation, has advantages for everyone. For the hermit crab, which always carries them with it, those polyps represent a precious life-saving protection. Sea anemones, in fact, are cnidarians, anthozoans, hexacorals. Cnidarians, as they have stinging cells that, placed on white filaments called acontia, come out as soon as they are attacked by predators. In this way, the anemones defend themselves and also the hermit crab that hosts them. Furthermore, their presence on the shells, favors their camouflage on the seabed, helping the hermit crab to hide more effectively from its attackers.
Even for sea anemones, the advantage of cohabitation is notable. First of all, thanks to the hermit crab that carries them on its shell, they can move around without any effort and with movement they have a greater chance of feeding. And then they can always make use of the leftovers from their host's meals. The host really takes care of them, willingly accepting their presence on the shell in which it is installed. And furthermore, every time it is forced to change it, it takes care to move one by one the anemones it lives with onto the new shell. Bernardo and his anemones are one of the most astonishing examples of mutualistic symbiosis that is established between the inhabitants of the sea depths.
For decades, the monk seal (Monachus monachus) has been practically a ghost, the protagonist of a few sightings in the open sea so rare as to deserve official announcements and prominent newspaper headlines.
Very delicate ribbons, arranged in a spiral, form transparent yellowish-white skeins that stand out on the dark rock, in sheltered and shady spots. They are deposited on the seabed by an animal with an unmistakable mantle, which also stands out among all the other creatures present in the marine environment. Flat, oval in shape, a milk-coloured body crawls slowly with numerous brown spots of various shapes and sizes, outlined by a darker edge. The common name by which this strange specimen is known, Sea Cow (Peltodoris atromaculata), is not surprising. A gastropod mollusc of the order Nudibranchs, completely without a shell, classified in the suborder Doridina because of the sensory appendages it displays on its head, called rhinophores, white and retractable. Another peculiarity is the gills, between six and nine and also retractable, which appear as a whitish tuft, located on the rear part of the body.
Those ribbons left on the bottom contain the eggs of the sea cow: very small, white or yellow in color, they are laid in various stages, during the summer period by the adults, who are hermaphrodites, both male and female at the same time. From the eggs, larvae are born, equipped with a tiny shell, which become part of the plankton, until, having escaped the many predators, they reach the right size to return to the bottom and begin life as adults, now without their shell.
On average, between five and seven centimeters long, the cows, also known as Dotted Sea Slug, can reach twelve centimeters. As they grow, the size of their spots also increases in proportion, and their shape is a characteristic element of each individual. During the egg-laying phase, which lasts for several days, the animal loses weight and becomes smaller. This, after all, is the culminating moment of its life cycle, which lasts a year and ends just a few weeks after reproduction.
Widespread throughout the Mediterranean, the Sea Cow lives between 5 and 50 meters deep, mainly on coralligenous and rocky substrates, but also in Posidonia meadows. Wherever its prey, which are sponges, are found. In fact, it spends most of its life on them, scraping their porous surface with its designated organ, the radula. The nudibranch is fond of only two species of sponges, Petrosia ficiformis and Haliclona fulva.
Its bright orange color stands out unmistakably on the walls of submerged caves or on rocks populated by corals, gorgonians and other animals characteristic of the coralligenous. What creates that extraordinary special effect in the depths of the Mediterranean and in some areas of the eastern Atlantic is not the single specimen of Parazoanthus axinellae, commonly known as yellow cluster anemone, given its tiny size, but the extension of the colonies, which group together thousands and thousands of polyps, fixed to the substrate with a soft and unique stolon.
They are really small, the polyps, just five millimeters in diameter and about twenty in height. Each polyp has a basal part and an erect part that is retractable. The entire body is equipped with stinging cells (cnidocysts) that place the anemone among the Cnidaria or also Coelenterates, because they have a gastric cavity called coelenteron. Belonging to the class of Anthozoa, being a polyp, the anemone is a hexacoral, because it has smooth, threadlike tentacles in number between 24 and 36, therefore multiples of six, arranged in two rows around the mouth and equipped, more than the other parts of the body, with stinging cells. Thanks to the tentacles, the polyps capture the microplankton on which the animal feeds. And precisely to have food available, the species settles in places where the movement of the currents is strong. Another requirement is low light, not by chance Parazoanthus is present in marine cavities or in any case on rocky walls in the shade. The depth varies from 5 to 50 meters mostly, but colonies are found up to 200 meters. Where it encounters favorable conditions, the species expands like a carpet even on very large surfaces. The colonies can merge or split.
The groups include male and female specimens, which reproduce in spring, with the laying of eggs in March. At the end of autumn, planktonic larvae are released from the eggs and are transported by the current to create new colonies.
If they prefer hard and rocky substrate, yellow cluster anemone can also settle on other animals. And their scientific name already reveals a symbiosis with some sponges of the Axinellidae family – Axinella darmicornis and Axinella verrucosa – which are also filter-feeding animals and have the same yellow color. In addition to sponges, anemones also settle on other species of sponges (Petrosia, Agelas and Sarcotragus), on tunicates of the genus Microcosmus and on the yellow gorgonians Eucinella cavolinii and on the white Eucinella verrucosa.
When you put it to your ear, you can hear the sea breathing. The god Triton always carried it with him, playing it to calm the stormy sea and to announce the arrival of his father Poseidon, the god of the sea. The large shell was precious to every sailor, who used it to launch his call to signal the position of the vessel in the fog or to announce the arrival in port. That unmistakable sound also resounded in the countryside, to call the flocks and accompany the special moments of the communities. For millennia, the sea trumpet has been a tool for communication, alarm and even defense against attacks by enemy ships approaching the coast. All possible thanks to a shell, the largest in the Mediterranean after the noble pen shell and among the largest in the world, with a tapered conical shape and bright colors, from white to brown, under the marine encrustations. Inside, an enormous mollusc of about sixty centimetres, which bears the name of the half-man, half-fish god: Giant Triton, Charonia tritonis for science.
For tens of millions of years on the planet, fossils testify to its presence in all seas as other molluscs of the same Charoniidae family, with very similar characteristics that sometimes make them difficult to distinguish. It lives in the oceans and in the Mediterranean, from the east to the Adriatic, to the Sicilian Sea up to the central Tyrrhenian Sea, at a depth between twenty and forty meters. And it prefers rocky or detritus seabeds. Where it finds in abundance the invertebrates on which it feeds such as starfish, sea cucumbers and bivalves.
It mostly devours them whole, even when they are large, and digests them, even the hard parts, thanks to acid secretions produced by the salivary glands. The giant triton is also able to produce saliva that can paralyze its prey, in order to feed on it.
This also allows it to eat the large crown-of-thorns starfish (Acanthaster planci), which live in the Pacific and Indian oceans. Although their rays are covered with spines for protection, they are useless against the giant triton, their only predator. As such, it is considered essential for the defense of the coral reef, which in turn is prey to the crown-of-thorns starfish, which can feed on corals, thanks to powerful digestive enzymes. It is estimated that a single starfish can destroy six square meters of reef a year and the proliferation of crown-of-thorns is seriously endangering corals in various parts of the planet.
For its part, the giant triton has become quite rare in the Mediterranean, where sightings are very few. The population of the mollusc has been drastically decimated by the intensive fishing to which it has been subjected even in recent times both because it is edible and to use its precious shell, no longer as a foghorn or musical instrument, but for collecting purposes.
The giant triton is a species protected by the Bern and Barcelona Conventions, so fishing is prohibited.
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