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Facts about Marble Rays

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Marble Ray facts

The Marble Ray has many names, including two scientific ones: Taeniura meyeni and T. melanospilos. Its common names include Black-spotted stingray, Giant reef ray, Marbled ray,Blotched fantail ray and Round ribbontail ray.

The first thing you notice about the Marble Ray is its great size. It can be 3 m in length and1.7 m wide. Round in shape it is covered with a dense pattern of black spots.

It is not aggressive but you need to be careful of the spines on the tail.

You see the Marble Ray in the Indo-West Pacific: Red Sea andEast Africa to southern Japan, Micronesia and tropical Australia;and in the Cocos and Galapagos islands in the Eastern Pacific.It occurs in a wide range of habitats, from shallow lagoons to outer reef slopes, and usually has other fish like jacks swimming near them.

Carnivorous, the Marble Ray eats bottom fish and crustaceans.

The female bears live young: the eggs are kept in the body of the female where the embryo develops. Up to seven pups hatch from the egg capsules and are born soon afterwards.

The ray is classified as “vulnerable” on theIUCN Red List of Threatened Species. This means that it is at high risk of endangerment in the wild. Although Australia and the Maldives protect the raythrough marine parks and prohibiting the export of raysand ray products, elsewhere the species is caught byline gear and trawl throughout its range. For example,in Indonesia Taeniura meyeni is regularly takenin low numbers by tangle netters operating out ofJakarta (Java), Bali and Merauke (West Papua), whiledemersal longliners that operate out of Lombok andlarge pair trawlers operating out of Meraukeirregularly take adults. The latter fishery comprisessome 650 vessels and pressure is intense where thevessels operate in the Arafura Sea. Low numbers ofjuveniles are also taken by prawn and fish trawlersaround Indonesia, particularly in the Java Sea.Overall, fishing pressure is significant over mostof the species’ range throughout Asia and across itsIndian Ocean range (India, East Africa etc). Additional pressure exists on its habitat in that region due to destructive fishing practices (dynamitefishing) and run-off impacting coral reef systems,the main habitat of the species.

Facts about Harlequin Shrimp

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Harlequin shrimp – Hymenocera picta

These beautiful shrimps have a very specific diet: starfish. Upon finding their prey, they will overturn it to dine on the starfish’s delicate tube feet.

These are small shrimps, typically 2-5cm (1-2in) in length.

They are Indo-Pacific, like Bali and the Gili Islands. When you are diving around the Gili Islands you can find them in the harbor of Gili Air and Sharkpoint.They live on coral reefs.

Harlequin shrimps eat starfish. They feed on the tube feet and will occasionally take whole starfish many times larger then themselves. They also feed on sea urchins.

Harlequin shrimps detect their prey using scent. They locate a starfish and prize its arms from the rock. The male and female shrimp overturn the starfish together to disable it. This allows them to feed on its delicate tube feet starting at the tips and working inwards. Sometimes they will take the starfish into a dark recess where they can continue to feed for several days. Some even feed the starfish prey, keeping it alive so that they can dine on it later.

Their extraordinary coloration may serve as a warning to possible predators. It is thought that the shrimps incorporate toxins from their prey, making them bad tasting or potentially dangerous to eat.

Reproduction of Harlequin shrimps are fairly rare. When they encounter a mate, they stay together for life forming monogamous, often territorial, pairs. They mate shortly after the female’s moult. The female produces between 100 and 5,000 eggs per season.

Why should we do Reef Clean Ups?

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If you have a choice to dive in a soup of plastic, the smell of petrol around you, seeing more rubbish than fish or diving in crystal clear water? The choice is easy isn’t it?

Reef Cleans ups around the Gili Islands

Marine debris also affects reefs in many areas. Marine debris is any human-made object that is discarded, disposed of, or abandoned that enters coastal and ocean waters. Debris may enter directly from a ship or indirectly when washed out to sea via rivers, streams, and storm drains. Hundreds of human-made items end up as marine debris, including plastics (from bags to balloons, hard hats to fishing line), glass, metal, rubber (millions of tires!), and even entire vessels.

Plastic debris kills several reef species. Derelict (abandoned) fishing nets and other gear—often called “ghost nets” because they still catch fish and other marine life despite being abandoned—can entangle and kill reef organisms and break or damage reefs. Even remote reef systems suffer the effects of marine debris.

This is why Oceans 5 dive resort organizes every week a Beach and Reef clean up in the Harbor of Gili Air, Lombok, Indonesia. Most of the time our Divemaster trainees, instructors, divemasters, and diveguides are organizing the event. Everyone can join, divers and non divers. It is free. The goal is to take all the rubbish out of the harbor of Gili Air. This is a hard job because during raining season it looks like that the harbor attracts all the rubbish and that the reefs collect it. But Oceans 5 dive resort believes that something has to be done. And with little help we try to protect a beautiful reef in front of the dive shop.

If you are on Gili Air, Indonesia just visit us if you want to know more about the clean ups or if you want to join.

Marine debris is everyone’s problem. It is a global problem affecting everything from the environment to the economy; from fishing and navigation to human health and safety; from the tiniest coral polyps to giant blue whales. Marine debris also comes in many forms, from a cigarette butt to a 4,000-pound derelict fishing net.

Marine debris is a problem we can solve together. Although marine debris is found worldwide, we can all help with the smallest actions. Reduce, reuse, recycle, and participate in local beach or stream cleanups. If we each do a little, together we can make a big difference.

Facts about Stargazers

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Stargazers (Uranoscopidae)

Stargazers are named for their peculiar appearance with eyes positioned dorsally on the head, usually with protruding eyes that are directed upward. The body is moderately elongate and depressed anteriorly. The large head is almost entirely encased in sculptured bones and also flattened. The large, nearly vertical mouth is equipped with small teeth and there is a peculiar respiratory valve inside the lower jaw that functions as a lure for attracting fish prey. The lips are fringed with numerous papillae in most species. They are also numerous tiny cirri along the fleshy posterior margin of the operculum. The gill openings are very broad and equipped with dorsal, valve like openings, which aid respiration when partially buried. A stout cleithral spine situated just behind each dorsal gill opening. This spine is venomous in at least some species and serious injuries have been reported.

Stargazers are generally nocturnal predators of fish and benthic invertebrates.

They are found on sand, silt, or rubble bottoms and are often seen partially buried.

The upwards directed eyes are useful for detecting prey in this position. When approached by a small fish the stargazer uses its peculiar luring apparatus to attract the victim to its well disguised mouth. The worm like lure, which varies in shape according to species, is thrust from mouth and wiggled vigorously.

The family contains 8 genera and approximately 50 species. Most species occur commonly on offshore trawling grounds, well removed from coral reefs. You will find stargazers in Lombok, Teluk Nara and around the Gili Islands in the front of Oceans 5 dive resort, Oceans 5 house reef.

Facts about Anthias

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Anthias (Anthinae)

Anthias , much smaller than their grouper relatives, also play an important role in the reef community. Anthias in particular are very abundant in terms of number of individuals and often form huge mid water feeding aggregations, especially adjacent to steep outer reef drop-offs, like when yo are diving around the Gili Islands Halik Reef.

The diet consists mainly of zooplankton and therefore, they are usually found in areas swept by periodic strong currents.

Generally males are more colourful and typically outnumbered by females. They exhibit a harem-type social structure with each male dominating a group of females, which in turn, have a pecking order hierarchy.

In the event the male is removed, either experimentally or by a predator, the highest ranking female changes sex and assumes control of the harem. The change is relatively rapid, beginning within several days and is generally completed in about two weeks. The transformation from female to male is facilitated by the presence of both testicular and ovarian tissue within the gonads. During the initial female phase only the ovaries are functional, but the assumption of social dominance triggers a hormonal reaction that suppresses ovarian development and stimulates the testicular tissue.

Reef Clean Up Gili Air with Oceans 5 Dive

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Yesterday Oceans 5 dive resort organized another reef clean up. Instructor Phil, Divemaster Yvonne and Divemaster Trainee Budi took care of 7 other divers who wanted to help.

The clean up started at 16.00. At that time the preparation started with preparing the bags, the gloves and all the equipment. At 16.30 Divemaster Yvonne gave a dive briefing about how everyone should take the rubbish away, the bottom time, the max depth and buddy teams.

The first divers came after 44 minutes out of th water. They had 3 bags full of rubbish. After this each buddy team and the result was shocking……

After we had last time 15 bags of rubbish now the divers collected another 12 bags of rubbish! It looks a little bit better in the front of Oceans 5 dive resort, but still a lot of work has to be done.

For further information about the reef clean ups: info@oceans5dive.com

Facts about Porcelain Crabs

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Porcelain crab
Neopetrolisthes maculatus

These delicately spotted crabs live in a symbiotic relationship with anemones. They keep the anemone clean while benefiting from its protection. Porcelain crabs have modified mouthparts which open out like fans into the oncoming current in order to trap tiny particles of plankton

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Life span

They live for around 2-3 years.

Statistics

They are less than 24mm in width.

Distribution

They are found in the Indo-Pacific. You see them when you are diving around the Gili Islands Indonesia.

Habitat

They are also known as anemone crabs, due to their close association with anemones. Porcelain crabs may be found singly or in pairs, hidden between the stinging tentacles, or near the mouth, of anemones. They are found in reef habitats, to depths of around 10m.

Diet

They are mainly plankton feeders, sieving tiny particles from the water column using their fan-like mouthparts. They also eat mucus from the anemone.

Behaviour

Porcelain crabs are relatively aggressive, using their large claws to deter invaders, including anemone fish. Although both use an anemone host, porcelain crabs and anemone fish are not commonly found together, the crab usually losing out to the tougher fish. Like anemone fish, porcelain crabs are immune to the anemone’s stinging tentacles. It is a mutualistic relationship, since both parties benefit from the arrangement: the crab gaining safety and shelter, in return for cleaning.

Reproduction

Porcelain crabs are often found in heterosexual pairs. They have internal fertilization, the male passing sperm to the female in the form of a tiny packet called a spermatophore. The eggs are carried by the female in a brood flap, on the abdomen. A single female may carry nearly 1,600 eggs at a time. The larvae are planktonic for several weeks before settling.

Conservation status

Porcelain crabs are not of the IUCN Red List, but suffer from habitat loss if reefs are damaged or polluted.

Max and Cindy, IDC candidates August 2012

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Hi,

We are Cindy & Max from France

We arrived in Gili Air as Advanced in May 2012 & we leaved the island in September as a PADI Instructor!

We grown up in the PADI family so quickly, it’s amazing!!!!

We were very lucky to had IDC & IE in Gili Air, which is a very nice but small island

We really enjoyed our IDC by Camille

We are not native English speaker, so we were a bit nervous and worried about that. The Question was, can we do it in English? But it was Ok, because Camille took time to repeat, speak slowly, explain : “tu as compris maintenant?”

The IDC was an intense 10 days: stress for our classroom presentation in English, homework after a long day, but every day we had a big fun, laught

The IE was like Camille said “It’s Easy”

Thank you again Camille

Thank you Sander & Simone of Oceans 5, Dive resort Gili Air

Cindy Balard & Maxime François, France, OWSI, August 2012, Gili Air, Indonesia

Facts about White Tip Reef Sharks

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Sharkpoint, West Gili Trawangan, Indonesia is one of the most exciting divesites around the Gili Islands. It takes 30 minutes by boat from Oceans 5 dive resort to get there. The main attraction are the White Tip Reef Sharks. You will find them between the 20 and 30 meters in the sandy patches between the reefs, mostly sleeping.

Description and Behavior

Whitetip reef sharks, Trianodon obesus, are a slender species with a short, blunt snout. They are brown-gray on their dorsal (top) sides, white on their ventral (lower) sides. They have scattered dark gray spots along the sides of their bodies.

The tips of their first dorsal fin and upper caudal (tail) fin lobe are brilliant white. The tip of their second dorsal fin and lower caudal fin lobe are also white in some animals. Spiracles usually present, teeth are tricuspidate (three-pronged, with a smaller secondary cusp on either side of the central blade) numbering 47-50 upper/44-46 lower jaw, in at least 2 functional rows.

This species is reported to grow to 2.3 meters in length but adults over 1.6 meters long are rarely seen. Maximum published weight is 18 kg and the maximum reported age is 25 years.

World Range and Habitat

Whitetip reef sharks are found in tropical marine waters, are most abundant on the fore-reef, and during daylight hours are often associated with coral reefs or lying on the bottom in caves and under ledges. Individuals often return to favored resting sites at the same times each day, often for several years. Highly social, these sharks often lie together in groups on the bottom, stretched out side-by-side and even stacked like chord wood. Home ranges of individuals are very small, typically only 0.5 km² or so.

In Australia they are recorded from northwestern Australia, around the tropical north and south to the Queensland coast. They are one of the most abundant species found near coral reefs, together with blacktip reef sharks, Carcharhinus melanopterus, and gray reef sharks, C. amblyrhynchos. They prefer shallow water, but have been found down to 330 m. These sharks live near the bottom or in caves and crevices. Compared to typical reef sharks (requiem sharks), this species swims in a more undulating manner. They are primarily nocturnal, but seem to be correlated with tidal ranges. They can be found in the same area for months (a few square kilometers) but territoriality is not known. They are sluggish inhabitants of lagoons and seaward reefs where they are often found resting in caves or under coral ledges during the day, or usually on a sand patch, or in a channel. They are more active at night or during slack tide in areas of strong currents. They are known to travel distances from about 0.3-3 km in periods up to about 1 year.

Feeding Behavior (Ecology)

Whitetip reef sharks feed nocturnally on benthic animals such as fishes, octopuses, spiny lobsters, and crabs. They have been observed feeding cooperatively at night at Cocos Island, Costa Rica, moving over the reef face like a phalanx of soldiers, flushing out sleeping prey. Foraging individuals often pause to wriggle their elongate bodies into crevices and under coral heads, twisting and turning violently and often breaking off coral and tearing their fins and skin. As such, the whitetip reef shark occupies a niche more like that of a moray eel than a typical shark.

Life History

One to five 60 cm young per litter. Mode: dioecism. Fertilization: internal (oviduct). Reproductive guild: internal live bearers. Description of life cycle and mating behavior: Viviparous, with 1-5 young per litter. Gestation is about 12 months. Size at birth 52-60 cm total length. Distinct pairing with embrace. One to 11 males follow a female until one gently nips her gill region; if she accepts him, he grasps one of her pectoral fins in his mouth and mates with her, their heads close together on the bottom and their bodies entwined and extending up into the water column at an angle of about 45 degrees. Mating typically lasts 1.5 to 3 minutes. They reach sexual maturity at an age of about 8 years and a length of about 1 m (males and females). Size at birth 52-60 cm total length.

Conservation Status and Comments

Check the Conservation Status of Whitetip Reef Sharks Note: if there are no entries found, it only means that this species has not yet been evaluated.

The whitetip reef shark is a curious species that often approaches divers. It is not considered dangerous to humans. Its restricted habitat, depth range, small litter size and moderately late age at maturity suggest that, with increasing fishing pressure, this species may become threatened .

Rarely reported to attack humans, but is potentially dangerous, particularly when when fish have been speared. Probably fished wherever it occurs (no data). Meat and liver utilized fresh for human consumption. The liver of this shark has been reported as toxic.