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Atlantis Diving Centre
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Myriapora truncata (False Coral)

Myriapora truncata, the False Coral is a magnificent Bryozoan, getting its common name from its resemblance to Red Coral (Corallium rubrum). It is native to the Mediterranean Sea.

The genus Myriapora belongs to the family Myriozoidae, order Cheilostomata, class Gymnolaemata, phylum Bryozoa, sub-kingdom Eumetazoa and kingdom Animalia.

Although Myriapora truncata resembles the Red Coral in colour and size, it is however much more fragile and loses its colour if removed from the sea. Colonies are anchored to rocky substrates, often characterized by coralline, in dimly-lit areas ranging from 2m to 100m deep.

Each colony, up to 10cm wide, has dichotomous branches, which are short and stubby, porous and with an intense red-orange colouring. Each branch is a cylindrical section, which appears to be truncated at the ends. The minute pores and corresponding tentacles represent the individuals that make up the colony. Unlike the true coral polyps, which are white, the polyploids of this species have the same colour as the ramifications.

Studies of the diameter of the branches and the size of the polyploids, varying according to the environmental conditions, have led to consider Myriapora truncata as an indicator of the environmental changes happening from the Cenozoic to the modern era in the Mediterranean Sea.

Like all Entoprocts, the growth of a colony occurs asexually (not involving the fusion of gametes), through pullulation. Everything starts with a single individual, a product of a sexual reproduction. This single animal (primary zooid), defined as ancestral, derives from the development of a larva. From the pullulation of the primary zooids, offsprings are born, which in turn pollulate, thus enlarging the colony. Finally, there is yet another sexual reproduction of the predominantly hermaphrodite animals, from which a new larva is formed.

When entoprocts were discovered in the nineteenth century, they and bryozoans (ectoprocts) were regarded as classes within the phylum Bryozoa, because both groups were sessile animals that filter-fed by means of a "crown" of tentacles that bore cilia. However, from 1869 onwards, increasing awareness of differences, including the position of the entoproct anus inside the feeding structure and the difference in the early pattern of division of cells in their embryos, caused scientists to regard the two groups as separate phyla. Bryozoa then became just an alternative name for ectoprocts, in which the anus is outside the feeding organ. However, studies by one team in 2007 and 2008 argue for sinking Entoprocta into Bryozoa as a class, and resurrecting Ectoprocta as a name for the currently identified bryozoans.

Both photos of this colony of False Coral were taken at a depth of 5m at Reqqa Point on Gozo’s north coast. In the main photo we can also see three Parrotfish (Sparisoma cretense) and a Fireworm (Hermodice carunculata), whereas in the inserted frame we can spot a Thuridilla hopei.

Photos taken by Brian Azzopardi
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Conger conger (European Conger)

Conger conger, the European Conger (a.k.a. Conger Eel) is a species of conger and is also the largest eel in the world. It is native to the northeast Atlantic Ocean and the Mediterranean Sea.

The genus Conger belongs to the family Congridae, order Anguilliformes, class Actinopterygii, phylum Chordata and kingdom Animalia.

European Congers have an average adult length of 1.5m, a maximum known length of 3m and a maximum weight of roughly 110kg, making them the largest eels in the world by weight. They can be rivalled or marginally exceeded in length by the largest species of moray eel but these tend to be more slender and thus weigh less than the larger congers. Females, with an average length at sexual maturity of 2m, are much larger than males, the latter having an average length of 1.2m at sexual maturity.

The body is very long and without scales. The colour is usually grey, but can also be blackish. The belly is white. A row of small white spots is aligned along the lateral line. The head is almost conical, and slightly depressed. The snout is rounded and prominent, with lateral olfactory holes. The large gill openings are in the lateral position. The conical teeth are arranged in rows on the jaws. The dorsal and anal fins are confluent with the caudal fin. Pectoral fins are present, while ventral fins are absent.

Conger Eels have habits similar to moray eels. They usually live amongst rocks in holes, or ‘eel pits’, sometimes in one hole together with moray eels. They come out from their holes at night to hunt. These nocturnal predators mainly feed on fish, cephalopods, and crustaceans, although they are thought to scavenge on dead and rotting fish, as well as actively hunt live fish.

This species can be found at depths ranging from 0 to 500m, although they may reach depths of 3600m during their migrations. It is usually present on rough, rocky, broken ground, close to the coast when young, moving to deeper waters when becoming an adult.

When the European Congers are between 5 and 15 years old, their bodies undergo a transformation, with the reproductive organs of both males and females increasing in size and the skeleton reducing in mass and the teeth falling out. Conger Eels then stop feeding and leave European waters and make the long migration to the subtropical areas of the Atlantic, such as the Sargasso Sea. Once in this area, they spawn, with the female producing 3 to 8 million eggs. Once hatched, the larval Conger conger begin to swim back to European waters, where they live until they reach maturity and then begin to migrate to repeat the cycle.

The main photo of this European Conger was taken at a depth of 5m at Reqqa Point while the insert photo was taken at a depth of 25m inside Billingshurst Cave. Both dive sites are situated on Gozo’s north coast.

Photos taken by Brian Azzopardi
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Muraena helena (Mediterranean Moray)

Muraena helena, the Mediterranean Moray (a.k.a. Roman Eel) is a fish of the moray eel family. It has an elongated, snake-like body and is found in the eastern Atlantic Ocean and the Mediterranean Sea.

The genus Muraena belongs to the family Muraenidae, order Anguilliformes, class Actinopterygii, phylum Chordata and kingdom Animalia.

The Mediterranean Moray can reach a length of 1.5 metres and weigh over 15 kilograms. Its coloration varies from dark grey to dark brown with fine dark spots. The skin is slimy and without scales. The dorsal fin begins behind its head and continues to the caudal fin (fused with the anal fin). Pectoral fins are absent, teeth are long and sharp-pointed (like other morays), while the mouth is long, robust and reaches behind the gills. It seldom attacks unless provoked.

Muraena helena prefers rocky bottoms and lives at depths ranging from 5 to 80 metres. It is a solitary, nocturnal and territorial species. The Mediterranean Moray spends most of the day in cavities and clefts between rocks and is more active at night. It hunts fish, crayfish and cephalopods, but also feeds on dead animals.

The Mediterranean Moray's reproduction is not well known. They spawn about 60,000 eggs into open water, from which planktonic transparent leptocephali hatch.

One parasitic crustacean, the trematode Folliculovarium mediterraneum and the flatworm Lecithochirium grandiporum are parasites commonly found on the Mediterranean Moray.

The photo of this Mediterranean Moray was taken at a depth of 15m at Reqqa Point on Gozo’s north coast.

Photo taken by Brian Azzopardi
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Cotylorhiza tuberculata (Fried Egg Jellyfish)

Cotylorhiza tuberculata is a species of jellyfish, also known as the Fried Egg Jellyfish or Mediterranean Jelly. It is commonly found in aggregations in the Mediterranean Sea, Aegean Sea and Adriatic Sea. The scientific name Cotylorhiza is derived from the Greek words “κοντύλι,” meaning cup, and “ρίζα,” meaning root.

The genus Cotylorhiza belongs to the family Cepheidae, order Rhizostomeae, class Scyphozoa, phylum Cnidaria and kingdom Animalia.

A typical adult Fried Egg Jellyfish measures 35 cm in diameter, though they can reach 50 cm across. The smooth, elevated dome of this elegant creature is surrounded by a gutter-like ring. The marginal lappets are elongated and sub-rectangular. Each mouth-arm bifurcates near its base and branches several times. In addition to some larger appendages there are many short, club-shaped ones that bear disk-like ends.

These jellies primarily feed on zooplankton and reproduce asexually. Larvae attach themselves to a hard ocean surface and grow in a polyp colony that looks like a stack of saucers. The tiny babies are then released from capsules, like spaceships and drift away.

With their alien-like appearance, jellyfish are notorious for their stinging nature and often dreaded by humans and other sea creatures alike. But the Cotylorhiza tuberculata touch is relatively harmless to both humans as well as the juvenile mackerel fish which dart in and out of the jelly mass. In fact, the Fried Egg Jellyfish is a floating safe house for the juvenile mackerel while it moves around with the planktonic drift.

Little is known about what leads to population explosions of jellyfish, but researchers attribute this phenomenon to favourable circumstances in the ecosystem. When the conditions are right there is a bloom. The sight of a medusa swarm can be breathtaking, as these docile creatures float graciously onward. Whenever there happens such a year with huge populations of jellyfish in general, swimmers and divers alike get concerned, such as what happened around the Maltese Islands two years ago. However, the following year there was almost nothing. Most Cotylorhiza tuberculata blooms around Gozo happen during the month of September.

One of Cotylorhiza tuberculata‘s natural predators is the sea turtle Caretta caretta. Luckily, the Fried Egg Jellyfish is not in immediate danger of disappearance, unlike the Caretta caretta. Yet, they are still important in the balance of sea life, as all these components are interconnected. In an optimal ecosystem, the system is even more stable with more biodiversity.

The photo of this Fried Egg Jellyfish was taken at a depth of 5m at Reqqa Point on Gozo’s north coast.

Photo taken by Brian Azzopardi
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with Brian Azzopardi & Jean-Marc Jefferson
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with Brian Azzopardi & Jean-Marc Jefferson
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Tripterigion tripteronotum (Red-Black Triplefin)

Tripterygion tripteronotum, the Red-Black Triplefin, is a blennioid, a small perciform marine fish in the family Tripterygiidae, the threefin blennies. It is endemic to the Black Sea and the Mediterranean Sea. The family name derives from the Greek tripteros meaning "with three wings".

The genus Tripterygion belongs to the family Tripterygiidae, order Perciformes, class Actinopterygii, phylum Chordata and kingdom Animalia.

With an elongated, typical blenny form, threefin blennies differ from their relatives by having a dorsal fin separated into three parts (hence the name); the first two are spinous. The small, slender pelvic fins are located underneath the throat and possess a single spine; the large anal fin may have one or two spines. The pectoral fins are greatly enlarged, and the tail fin is rounded. The Red-Black Triplefin grows to a maximum length of 8 cm but most other species do not exceed 6 cm.

Many threefin blennies are brightly coloured, often for reasons of camouflage; these species are popular in the aquarium hobby. As demersal fish, threefin blennies spend most of their time on or near the bottom on coral and rocks. The fish are typically found in shallow, clear waters with sun exposure, such as lagoons and seaward reefs, hardly ever deeper than five metres; nervous fish, they retreat to rock crevices at any perceived threat.

Threefin blennies are diurnal and territorial; many species exhibit sexual dichromatism, with the females drab (dull coloured) compared to the males. The second dorsal fin is also extended in the males of some species. Small benthic invertebrates comprise the bulk of the threefin blenny diet.

The expected lifetime of Tripterygion tripteronotum is only 3 years!

The photo of this Red-Black Triplefin was taken at a depth of 6m inside the Blue Hole, a natural feature at Dwejra on Gozo’s west coast.

Photo taken by Brian Azzopardi
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Chromodoris luteorosea (Yellow-Spotted Doris)

The Yellow-Spotted Doris is a species of colourful sea slug, a dorid nudibranch, a marine gastropod mollusc in the genus Chromodoris, family Chromodorididae, superfamily Doridoidea, order Nudibranchia, class Gastropoda, phylum Mollusca and kingdom Animalia.

This species occurs in the Mediterranean Sea, and on the Atlantic coast of Europe and Africa from the Bay of Biscay to Cape Verde and west as far as the Azores.

Chromodoris luteorosea is a chromodorid nudibranch which grows to a maximum length of 55 mm. It is easy to identify by its colours. The body’s pale purple mantle is edged with a bright yellow line, with intense yellow or whitish points, circular or oval and irregularly distributed over the surface. These conspicuous points are surrounded by a white ring.

The rhinophores measure 6 mm in length and have 15 lamellae at the top. They are violet or reddish with a white pigmentation. The gills are in the back, surrounding the anus, and are formed by 9 leafy branches, of the same colour as the rhinophores.

Chromodoris luteorosea lives on the sponge Spongionella pulchella or Aplysilla rosea from 5 m to 60 m deep, in the sublittoral zone.

This photo was taken at a depth of 40m at Għasri Point on Gozo’s north coast.

Photo taken by Brian Azzopardi
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