• Photo by Rantje Allen

  • Photo by William Tan

  • Photo by Rantje Allen

  • Photo by William Tan

  • Photo by Rantje Allen

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Category Archives: Dive Experience

Seahorses Rocking and Rolling in the Deep

Seahorses are favorites of many divers. Gorontalo waters host several different species. Pygmy seahorses are so cute, but many divers love ones that are big enough to see.

The Common Hippocampus kuda

Hippocampus kuda is the most predictable seahorse for divers to see. Its English name varies considerably. Some call it the Common seahorse. Others call it Estuary seahorse. It lives in shallow waters of mangrove swamps, estuaries and bays. Colors are generally dull, mainly blacks and browns. A yellow colored Common seahorse will be female.

female seahorse
A female seahorse lies quietly on the sea floor

Their dull pattern makes them look like debris lying on the ocean floor. This way they wait for small crabs or shrimp to come by. These seahorses suck in their prey whole through their long mouth. They do not have any teeth.

Rocking and Rolling

The Common seahorse is usually solitary. Sometimes, two of them will be lying still on the sand bottom near to one another. One day we saw several of them rocking and rolling in the deep. Watch Sami Lindross’s great video.

Pregnant Males

seahorse video
Watch the video!

Seahorses are most famous for their unusual biology. Males are the ones to give birth not the females. A mature male will develop a brood pouch on his belly. The female inserts her eggs into this pouch for the male to fertilize. The male’s pouch has placental fluid which surrounds the embedded eggs. This fluid provides oxygen, nutrients and waste disposal for the developing eggs. Moreover, the fluid becomes saltier. That way the babies are already adapted to salt water when they hatch. Pregnancy lasts 20 to 28 days. Then the male goes into labor, releasing the baby seahorses from his pouch.

Seahorses in Gorontalo

The Common seahorse is found at several dive sites in Gorontalo. However, finding them will often require a skilled dive guide. Even after they are found, they can easily drift away. For poor swimmers, seahorses can disappear quickly when they feel disturbed or threatened. For your chance to sight a seahorse in Gorontalo, please book your dive trip with us.

Mackerel Feeding Frenzy

Mackerel feeding frenzy! Right beside the dive boat, guests of Miguel’s Diving watched schooling Big mouth mackerel feeding off Jinn Caves dive site.

Regional Names

mackerel feeding frenzy
Flashes of silver

This small mackerel is found throughout tropical Indo-West Pacific seas. Its scientific name is Rastreliger kanagurta. In the Indian Ocean it is commonly called Indian mackerel. In the western Pacific it is commonly known as Big mouth or Mouth mackerel. Sometimes Long-jawed or even Rake-gilled mackerel is its common name.

Big Mouth Mackerel feeding

This fish is easily recognized. Its feeding pattern is distinctive. It filters microscopic marine life from the water by opening wide is mouth. Then it swims quickly into those pools of plankton. Its gill rakers strain food from the water. When its mouth is open, its head looks bigger. Notice in the video how the head flashes silver during mackerel feeding time.

Notice in the video all the particles in the water near the surface. Those particles are living organisms plus some floating sticks and leaves. Surface winds and ocean currents have pushed plankton into the small cove near the dive site. This created perfect conditions for a mackerel feeding frenzy. Visibility below was nearly 30 meters.

Up the Food Chain

Big mouth mackerels feed on the smallest marine life forms. This included diatoms known as phytoplankton. They also eat microscopic animals known as zooplankton. Adults prefer macroplankton, like shrimp larvae and fish eggs.

This fish is an important part of the diet in coastal areas of the Indian Ocean. It is canned, dried-salted and smoked. It is also made into fish sauce. In Gorontalo this fish is mainly ignored. Locals prefer Yellow-fin tuna, which is available in deep waters just off the coast.

For your chance to watch Big mouth mackerel feeding, please book your dive trip with us.

Sea Sapphires Mysteriously Disappear

Sea sapphires are flashy planktonic crustaceans that appear and disappear. No one knew how they did it – until now.

Suddenly Visible

In Gorontalo waters on certain days, divers are ready to descend. They notice tiny flashes of color in the water column. The flashes look like chips of iridescent blue paint. Sometimes the color is yellow. Occasionally, it is golden red. Upon closer inspection, those tiny ovals of blue are plankton floating in the water. Approach one with your finger. It will swim away and disappear. They are commonly called sea sapphires.

In the early mornings Gorontalo fishermen report seeing the ocean shimmer with these iridescent flashes. An old expression used by Japanese fishermen is tama-mizu. This means “jeweled water.”

The Life of Sea Sapphires

a male sea sapphires
A male sapphirina copepod

These brilliant and mysterious creatures are actually sapphirinid copepods. Copepods are a subclass of tiny crustaceans. They have elongated bodies and forked tails. Their scientific names reflect their jewel-like appearance.

Only male sea sapphires flash brilliant colors. They are carried by ocean currents, along with other planktonic life, to the coral walls of Gorontalo. Sea sapphires are an important part of the food chain. When we see them collecting off a dive site, we look out for whale sharks.

Female sea sapphires do not float the oceans with the free-swimming males. Instead, they congregate inside certain kinds of transparent jellys. Females have much larger eyes than males. Perhaps this allows them to scan the vast ocean for flashy boyfriends. Watch them in incredible Kaj Maney’s video.

The Arts of Reflection and Disappearance

A team of scientists from the Weizmann Institute of Science just discovered how male sea sapphires appear and disappear. Their study was published in June 2015. Males have alternating layers of hexagonal-shaped crystals. These are imbedded in their backs. Sea sapphires are only a few millimeters in length. But researchers managed to measure the distance between those reflective crystals found in sea sapphires. They used live males. The distance between crystals was only about 1/10000 mm. This measure is about the same as a wavelength of blue light. When sunlight hits male sea sapphires, only one color is reflected by the crystals. Usually, it is blue. Differences in color depend on the distance those layers of crystals are from one another. That is why some sea sapphires appear yellow or golden. This type of coloration is called structural coloration.

 tiny male sea sapphires
A tiny male sea sapphire reflects blue

Male sea sapphires swim freely in the open ocean. However, they do not swim in straight lines. They swim in spirals. Researchers also discovered how these sea sapphires disappear so quickly. As they turn, the angle of reflected light changes. When light hits them at a 45-degree angle, the reflection shifts out of the visible light range. Only ultraviolet light is reflected. Since humans cannot see ultraviolet light, male sea sapphires seem to disappear. They do this by merely turning their bodies. Although how they appear and disappear is now known, no one knows why.

Thysanostoma thysanura Jellyfish in Gorontalo

Thysanostoma thysanura is a large jellyfish rarely seen in Gorontalo waters.

Bushy Oral Arms

Thysanostoma thysanura in Gorontalo
Thysanostoma thysanura surface swimming

This large jellyfish lives in warm waters from the central Indo-Pacific to Japan. It was named in 1880. The Latin word thysanura means “bristle tails.” This name refers to the large, bushy oral arms that hang from the jellyfish’s central bell. Modern researchers have gathered specimens from Sulawesi, the northern Philippines and the Great Barrier Reef in Australia. Thysanostoma thysanura has been seen at depths reaching 24 meters. In Gorontalo, however, it has only been observed at the surface.

Encounter with Thysanostoma thysanura

Although Miguel’s Diving has been operating in Gorontalo since 2003, we have only encountered Thysanostoma thysanura a few times. After a dive in April 2015, one was swimming around the dive boat. Jellyfish of any kind are usually not present in areas where we dive. Imagine the excitement to see this large and beautiful jellyfish. In our experience, this jellyfish is a very active swimmer. It pumps water with its bell to move. Its oral arms drag along behind it. Taking photographs was a challenge because it never stayed still. Watch our video!

Jellyfish Facts

Adult jellyfish are called medusa. They have a soft body consisting of a bell with tentacles or oral arms surrounding a central mouth. Solitary medusa, like Thysanostoma thysanura, swim freely in the open ocean.

 

a rare Thysanostoma thysanura
A rare encounter in Gorontalo

Jellyfish are most famous for the stinging cells contained in their tentacles. The stinging cells are called nematocysts. They are microscopic and sensitive to pressure. Even a causal touch triggers hundreds or thousands of nematocysts. They fire like darts. Jellyfish use them to immobilize prey like small fish.

Some jellyfish are considered dangerous to humans. We have never seen any of these in Gorontalo. Since Thysanostoma thysanura is so large, avoiding it is quite easy. Since this jellyfish is so rare, only a few lucky divers will ever see it. Our jellyfish was kindly identified by Wyatt Patry of Monterrey Bay Aquarium.

Diving in Gorontalo is exciting because of the unusual marine life found here. For your chance to experience the beauty of Gorontalo, please book your dive trip with us.

Whale shark alert

Whale shark alert! Miguel’s Diving staff often see these giants of the sea.

Whale Shark Alert

This month we have seen a whale shark on three different days. That makes for a whale shark alert!

Guests with Miguel’s Diving staff today enjoyed seeing a 6 to 7 meter long whale shark. We are currently assisting with a coral research project. Everyone was distracted from the work at hand. Perhaps the whale shark wanted to help.

whale shark alert
A Whale Shark visits divers in Gorontalo

This was actually the third whale shark alert this month in Gorontalo. Last week a small one, measuring only three meters, got lost in shallow waters. That means this one is still quite young. Local fishermen towed it out to sea and to safety.

The first one sighted by Miguel’s Diving staff earlier in the month was not quite as large as the one today. That would make three different whale sharks.

Giants of the Sea

Whale sharks are the largest fish in the world. Adult size is around 10 meters. Some say that they can grow up to 14 meters. Whale sharks can weigh up to 21,000 kilos. They can live up to one hundred years.

They eat plankton and small fishes. They suck in water near the surface that is rich in plankton. Edible items are sifted through their fine teeth and swallowed. Water is evacuated through its five gills slits. They can actually eat large volumes this way. That is what allows them to grow to enormous sizes.

They are found in warm, tropical waters worldwide. They are not found in the Mediterrean Ocean. They often migrate great distances. They are commonly seen on the surface. However, research shows that they can dive below 1,250 meters.

Other dive locations in Sulawesi do not expect to have a whale shark alert. However, divers in Gorontalo can see them. For your chance for a whale shark alert, please book your dive trip with us.

Great Hidden Natural Treasure along the Reef

Leaf Scorpionfish SulawesiWith west weather bringing lots of rain to diving destinations in North Sulawesi, diving season in Gorontalo is at its prime. Typical weather is flat blue seas with a brief late afternoon shower. In addition to Bumphead parrotfish, large snappers, schools of fusiliers and anthias and Pacific triangular butterflyfish and Redtooth triggers, a hidden natural treasure in the shape of a large scorpionfish resting on a giant sponge caught the eye of passing divers. But that fish had its eyes on something swaying like a dead leaf. Sure enough, a beautiful Leaf scorpionfish (Taenianotus triacanthus) was only inches away. Back on the boat divers speculated if the larger fish intended to eat the smallerone or if the venonous dorsal spines would prevent this. After the diving for the day was over, diving staff checked and the smaller Leaf scorpionfish was still perched in the crevasse of the sponge. Those diving with Miguel’s today enjoyed visibility of over 20 meters on each dive.

Watch out

Gorontalo’s pristine corals tempt divers to look away from the blue water. Yesterday off the walls divers watched a school of about twenty large snappers and then a school of about 100 Big-eye trevally blasted by us. A Hawksbill turtle sailed slowly away. We have been seeing turtles every day. Then at the beginning of the last dive a pair of Bottle-nose dolphins swam past the divers. Visibility has been over 20 meters lately.

Auspicious Beginning of Lunar New Year

Divers spending Lunar New Year with us in Gorontalo dived a cavern, submerged point and muck all in the same day. First was the eerie darkness of Jinn’s Caves, one of Gorontalo’s signature dive sites. Then on the second dive we encountered a 70-kilo Dogtooth tuna not once but twice! It passed so close that no one needed the 30-meter vis to see it. On the final dive of the day a Mimic octopus tried all kinds of shapes and movements to confuse us. We hope to post a video on our Facebook page after guests return home to process what they shot. An auspicious start to the Year of the Dragon!

Follow your dive guide

Miguel’s Diving has three guides ready to assist our guests in the water. They are not only there for safety, helping with equipment and those sorts of things, but also to show divers the hidden paradise of Gorontalo that others miss. Yesterday for instance, those diving in the group with our divemaster were shown a school of about 30 tuna that swirled past three times in blue water. Not to be out done, our senior dive guide found about 100 rare skeleton shrimps for those diving with him. Ironically, the pelagic encounter and the rare macro find were on the same dive and within 50 meters of each other. That is Gorontalo diving!

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