Our Blog - Sulawesi Diving with Miguel's Diving in Gorontalo, Indonesia's hidden paradise

Photo by Rantje Allen
Photo by William Tan
Photo by Rantje Allen
Photo by William Tan
Photo by Rantje Allen

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Black Velutin Snail makes rare appearance

Posted on July 8, 2024 by Miguel's Diving • 0 Comments

Coriocella nigra, or the Black Velutin Snail, so easily hides that divers rarely see it. However, one day this dive season, staff found one during the safety stop. This one was only the second snail we have seen in over twenty years of diving here.

Coriocella nigra, a rarely seen snail

The Black Velutin Snail is so unusual that it gained its own genus. In 1824, Henri Marie Ducrotay de Blainville created a new genus and species for this snail. He named it Coriocella nigra. This name is still valid today. At the time, there was only this one species in the genus Coriocella. Currently, there are several more, based on more recent scientific studies.

It lives in rocky environments from very shallow depths down to about fifteen meters. The one in our photo measured about 8 centimeters long. This snail can grow a bit longer. Although found throughout the Indo-Pacific region, divers rarely seen it, despite its size. Natural camouflage disguises it.

Researchers speculate that this sail eats tunicates. Traces of octocoral have been detected in its intestines.

Varying Descriptions of the Black Velutin Snail

The color of the snail’s body is usually black or brown with shaded highlights in different colors. The Coriocella nigra that we found here in Gorontalo was unusually yellowish.

Most distinctive are the many smooth lobes that project from the main body. A closer look will reveal a longer projection at one end of the Black Velutin Snail. In our photo, it appears on the lower left. This is the snail’s inhalant siphon. Underneath the siphon will appear tenacles. On the tenacles are the snail’s eyes. Our snail was at rest, so its eyes were tucked inside.

Shell in a Snail

Unlike most types of snails, the Black Velutin Snail lives outside of its shell. Its shell is entirely inside! The shell of Coriocella nigra is translucent white. It usually contains two and a half whorls. However, the largest snails will have grown three whorls. It is thin and delicate. The length of this internal shell will be about a quarter of the length of the snail.

Although divers are unlikely to see a Black Velunid Snail anywhere in the world, they can see many other delightful creatures in Gorontalo. To do so, please make your dive reservations directly with Miguel’s Diving.

Longnose filefish bob away

Posted on June 17, 2024 by Miguel's Diving • 0 Comments

Longnose filefish are rare inhabitants of Gorontalo’s shallow reefs. But one lucky diver shot a video before they bobbed away.

By Many Names

The scientific name for this beautiful fish is Oxymonacanthus longirostris. That name means “long nose.” However, the English name is sometimes Orange-spotted filefish. Other times, it is Harlequin filefish. These names reflect the fish’s colorful body pattern.

Distinctive Beauty

The Longnose filefish has unmistakable coloring. Its pale blue body sports about seven irregular rows of bright orange spots. These spots are darkly rimmed. Yellow starting from the forehead colors the length of the fish’s long face. The skin surrounding the eyes is orange with flecks of pale blue. At end of its tail is a black blotch. Under the fish’s belly is a small, irregular black patch covered with tiny white dots. This dark patch is often unnoticed.

Also unnoticed is the fish’s file. All filefish have a sharp spine on the top of the head. Most of the time, this spine is folded tightly flush with the skull. Sometimes, however, the Longnose filefish will flex its head spine, and careful divers can observe it briefly.

Video of Longnose Filefish

Divers rarely see Longnose filefish in Gorontalo. These fish prefer shallow waters here of less than two meters. So, looking for them during a safety stop is a good idea. However, spotting them is unlikely since they are rare here. They also move and turn quickly to remain out of sight. These filesfish swim in irregular ways, bobbing and twisting. They swim in pairs or small groups.

Enjoy the brief video shot by one of our guests several years ago.

Form and Function

The prominent nose of the Longnose filefish serves an important function. As seen in the video, these fish prefer to inhabit areas of Acropora. Branching Acropora are common in shallow reefs in Gorontalo. Notice the fleshy lips at the end of the fish’s nose. Longnose filefish feed on Acropora polyps, using its pointed mouth to suck the polyp into this mouth. Scientists call this way of feeding cephalopharyngeal teeth protrusion. That means the fish quickly extends its jaws. With the vacuum created, the fish can suck the coral polyp from its home.

*Oxymonacanthus longirostris* in Gorontalo

Researchers also say that this fish absorbs chemicals from the coral polyps to mask the fish’s scent. This helps protect the fish from predators. Its irregular swimming patterns also aid it. Other researchers state that Longnose filefish also eat tiny crustaceans.

Adult Longnose filefish measure about 12 to 19 centimeters. However, those found in Gorontalo are about half that size. They are occasionally found throughout Indo-Pacific waters in shallow, ocean-facing reefs.

For your chance to search for this beautiful fish in Gorontalo, make your dive reservations directly with Miguel’s Diving.

Funnelweed pass unnoticed

Posted on May 1, 2024 by Miguel's Diving • 0 Comments

Funnelweed, though found worldwide, lives in limited locations in Gorontalo. Divers certainly pass by without noticing. But scientists are researching it.

Delicate scalloped algae

Although funnelweed is a member of the brown algae family, its color here in Gorontalo is not brown. It grows in some sandy patches or substrate among other algae. Its color is pale cream. Sometimes, it has tinges of light green.

It grows in beautiful, radiating ribbons. Opaque bands alternate with more transparent ones. Often, this algae forms scallops that curve inwards. On the outer edges and surface sprout almost transparent filaments.

Divers, who take the time to notice funnelweed, quickly appreciate its unique beauty. However, they should not brush against it with unprotected skin. Something about these algae here leaves itchy stings.

Funnelweed around the World

In Gorontalo, this beautiful plant only grows in a few small areas. A few sandy patches are full of these algae. In a couple of other sites, it grows among other algae.

However, it is found worldwide. This includes the Caribbean and Atlantic oceans, as well as the Indian and Pacific ones. The detailed list of locations is quite long. The scientific name for funnelweed is Padina gymnospora. Since it lives in so many oceans, scientist the world over are researching its potential value.

Scientific Research on Padina gymnospora

One group has extracted sulfated polysaccharides from it. Their research indicates anti-inflammatory properties. They used mice in their studies prior to potential use on humans.

Other researchers discovered anti-amyloidogenic agents in funnelweed. This extract in an important component in drugs that combat Alzheimer’s disease.

Field research on Padina gymnospora has found significant absorbent properties in the algae. A synthesized compound from it is over 80% effective in absorbing industrial dyes. Removing these dyes from industrial waste is a priority to build a cleaner world. Using this extract is clean and green solution in reusing industrial wastewater.

Padina gymnospora produces an aragonite calcium carbonate compound as well as phlorotannins. These are found on the algae surfaces. These compounds play an important role in defending the algae from worms and snails.

That chemical protection has no effect on Green turtles, which are herbivores. Padina gymnospora is actually edible. Naturally, it contains no heavy metals or toxins. Although no one really uses funnelweed for human food, it has potential for as a natural fertilizer.

In Gorontalo, only staff of Miguel’s Diving will know where to find these beautiful algae. To see for yourself, please make your dive reservations directly with us.

Duncanopsammia peltata forms pagodas in Gorontalo

Posted on February 6, 2024 by Miguel's Diving • 0 Comments

Duncanopsammia peltata or pagoda coral form immense colonies in Gorontalo’s healthy waters.

Stunning Pagoda Coral Colonies

One of Gorontalo’s ancient and stunning coral formations is pagoda coral. Giant plates form spirals, hence the common name denoting pagodas. The colonies featured in this video measure over four meters across. The video is courtesy of @jhonheriano of Pertamina Dive Club.

Other colonies of this distinctive coral form single plates. Additional plates may take several centuries to form. In other coral reefs of the Indo-Pacific region, this coral forms pillars. That morphology has yet to appear in Gorontalo.

Descriptions of Duncanopsammia peltata

The scientific name for pagoda coral is Duncanopsammia peltata. When we consulted coral experts, they asked for a detailed photograph of the polyps. These are distinctive in determining the species. Usually, corallites measure between three and five millimeters in diameters. However, those of the giant colony featured here measure almost one centimeter!

As with other corals, polyps are only found on the upper surfaces of the colony. They need sunlight and easy access to plankton brought by passing ocean currents. Sometimes, the corallites are embedded flush with the coral plate. However, other times they protrude above the plate like little bumps. Typically, the polyps are extended during daylight hours, ready to sunbathe and catch plankton. Their many arms can measure up to one centimeter in length.

Tiny single-cell organisms called zooxanthellae live inside Duncanopsammia peltata. They turn sunlight into food that they share with their host coral.

Colonies of Duncanopsammia peltata live in coral reefs throughout the Indo-Pacific region. They thrive just below the surface, down to a depth of about forty meters. The color is grey to light brown.

Ask us to show you Gorontalo’s pagoda corals when you make your dive reservations directly with Miguel’s Diving.

Dendrodoris tuberculosa inhabits Gorontalo reefs

Posted on January 12, 2024 by Miguel's Diving • 0 Comments

Dendrodoris tuberculosa rarely appears on Gorontalo’s coral rich dive sites, despite its very large size. After years of absence, in late 2023 divers saw three in the same week!

The Frilly Dendrodoris tuberculosa

Sometimes called the Tuberculate Dendrodoris nudibranch, it can grow to twenty centimeters in length. Colors range from brown to green to pink. Most distinctive about this giant nudibranch are its numerous tubercules. These almost entirely cover its upper body. Among the masses of tubercules, two rhinophores emerge. Perhaps because of its large size, it crawls quite fast. Despite its size, divers can easily miss seeing it.

Three in One Week

The first of three we spotted recently looked like a scrap of old carpet flowing over the substrate. It easily blended in and quickly disappeared under some coral. This sighting was at a depth of two meters. Its length was twenty centimeters.

The second Dendrodoris tuberculosa sighted was at twelve meters. It was crawling on top of plate coral that projected from one of Gorontalo’s spectacular walls. Its pinkish color contrasted nicely with the coral. Much smaller than the first, it measured about twelve centimeters in length. After crawling across the coral, it turned upside down and disappeared underneath the coral.

The third Tuberculate Dendrodoris had beautiful bluish tips on its tubercules. It was still on the small side, measuring about ten centimeters.

Discovery during Around-the-World Expedition

This enormous nudibranch was first discovered during a scientific voyage around the world. Commissioned by the French king, the voyage departed the port city of Toulon on 22 April 1826. The name of the ship was Astrolabe, after an instrument used in marine navigation. Scientists on board collected samples of animals and plants from the coasts of Chile and Peru, Australia, New Zealand, New Guinea, and various Pacific islands. They also surveyed the Molucca islands of Indonesia.

Two French naturalists Quoy and Gaimard named one discovery Doris tuberculosa. The genus name later changed to Dendrodoris.

The expedition returned to France in March 1825.

For your chance to enjoy a dive expedition in Gorontalo, please make your dive reservations directly with Miguel’s Diving.

Dead nudibranch startles divers

Posted on December 11, 2023 by Miguel's Diving • 0 Comments

Dead nudibranch is rarely seen. But one of our sharp-eyed dive masters spotted one along an unnamed section of coral reef.

A Black, Fleshy Mass

Miguel’s Diving staff are always looking for marine life to show to our diving guests. They are skilled in spotting small critters, as well as pelagics that swim past divers who are focused on the amazing coral here.

Recently, a dive master noticed something out of place in a small patch of white sand. The object looked black and fleshy, like the mantle of a clam. However, he knew that no clam lived there in the sand.

With a piece of broken coral, he probed the strange thing. It was clearly dead and lifeless. Upon closer inspection, it was clearly the dead body of a large nudibranch. Round holes remained where the rhinophores had been during life. Towards the back, the area where the gills should have been were completely torn. We have placed circles around the missing dorsal parts in the photograph.

Turning the dead nudibranch over on its back, he saw that the entire area of internal organs was entirely ravished. Only the fleshy body of the dead nudibranch remained.

An Expert Comments on the Dead Nudibranch

Everyone at Miguel’s Diving was curious to learn about this unusual sighting. None of us had ever seen a dead nudibranch before. We wanted to learn how this marine critter could have died. So, we contacted an expert. She is Prof. Dr. Heike Wägele of the Leibniz Institut zur Analyse des Biodiversitätswandels Zoologisches Forschungsmuseum. She kindly responded to our email.

belly — Ventral side showing missing interior parts

She speculated that the nudibranch could have experienced an injury to its back. As a result, fish began to nibble at it. Another alternative could be damage from a parasite. “Copepods usually sit close to the gill and perhaps this has also weakened the animal,” wrote Dr. Wägele. Sometimes, the nudibranch ages and dies naturally.

We also asked her why only parts of the dead nudibranch were eaten and not its body. She responded, “Usually these animals have toxic compounds accumulated in the body, mainly actually in the large body. But the organs are usually less toxic.” Also, the bodies of nudibranchs are full of spicules. Spicules are hard and spiny. They help support the body structure of marine animals that lack bones. Also

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, they make their bodies unpleasant to chew.

Once Alive

Given the extreme decay of the specimen, there is no way to know what species of nudibranch we found dead. However, its shape and size are similar to Ardeadoris egretta. Divers occasionally see this beautiful white nudibranch along coral reefs in Gorontalo.

For your chance to see a living nudibranch, please make your dive reservations directly with Miguel’s Diving.

Sargassum frogfish delights divers

Posted on November 23, 2023 by Miguel's Diving • 0 Comments

Sargassum frogfish float on surface currents to dive sites in Gorontalo. Our diligent diver masters know how to find them, to the delight of guests.

Floating Refuge

As their common name implies, Sargassum frogfish hide among sargassum weeds. Although these weeds initially grow along shallow ocean bottoms, storms will rip them up. Then, these weeds will float on the surface. They have air-filled bladders that look like berries, which helps the weeds float.

Over eighty species of fish use floating mats of Sargassum weed for part of their life cycle. Juvenile fish can hide there from predators. But predators also lurk unseen among the weeds.

Camouflaged Predator

One such predator is the Sargassum frogfish. Like other frogfish

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, this one has a small lure between its eyes and mouth. When the fish is hungry, it will wiggle its lure to tempt prey to approach too closely. With a sudden, giant gulp, the frogfish will ingest the small fish, crab or shrimp. Unhappily, baby frogfish may also be devoured.

This frogfish’s scientific name is Histrio histrio. It is the only species of this genus and no other fish looks quite like it. Its appearance is unmistakable, although finding it is difficult. Its coloration mimics that of Sargassum weed. Also, it has fleshy appendages that look like its weedy host. Although it can swim, this frogfish usually remains motionless. Instead, it grabs onto weeds with its pectoral fins and tail. When necessary, it can alter its color from lighter to darker, or vice versa.

Techniques for Finding Sargassum frogfish

Our dive masters are skilled in finding these shy and delightful critters. During surface intervals between dives, they will search floating weeds near the dive boat. If they find one, they will scoop it into a small bucket along with the weed on which the frogfish clings. That way guests on the dive boat can see it up close. Although this frogfish can survive quite a while above water, we always return it safely to the ocean.

For your chance to see a Sargassum frogfish Gorontalo, please make your dive reservations directly with Miguel’s Diving.

Estuarine stonefish horrify divers

Posted on October 16, 2023 by Miguel's Diving • 0 Comments

Estuarine stonefish look like ugly stones on the ocean floor. Moreover, they are buried in sand. Divers often pass this deadly fish without noticing.

Lurking Danger

Synanceia horrida is scientific name for the Estuarine stonefish. Famous naturalist Carl Linnaeus found it in Ambon, Indonesia in 1766 and gave the fish its “horrifying” name.

Most often, the Estuarine stonefish will hide under sand or rubble on the substrate. It uses its large pectoral fins to dig down. Then, it will wiggle its body, covering itself with sand. Typically, only its eyes and mouth emerge. Its mouth is always positioned like an unhappy up-side-down smile. Other times, it sits on the substrate looking like an uninteresting rock .

This grumpy looking fish is merely waiting for the right moment. As a night time hunter, the Estuarine stonefish waits for a fish, shrimp, or crustacean to pass by. With sudden inhalation, the fish will suck its prey into the mouth.

Venomous not Poisonous

Like other stonefishes, the Estuarine stonefish has a series of spines. These are usually lying flat onto its back. If the fish it started or feels threatened, it will erect its spines. If someone steps on it or grabs its, the spines will inject venom. This venom quickly and adversely affects the heart and muscles. The pain is extreme and deaths have occurred.

The best emergency treatment is submerging the wound in very hot water. Heat is a general tool for all marine venom and stings. It breaks down the neurotoxins, eventually rendering them neutral. Naturally, any victim should be taken to a medical facility.

Estuarine stonefish and its Lookalikes

Many of the bottom dwelling stonefishes look similar. However, only the Estuarine stonefish has the boney ridge between its eyes. Its eyes point upwards for sunken depression on the fish’s face. The fish’s color is dark and mottled. Oftentimes, filamentous algae will be growing on its body. All this is to disguise the fish’s presence. In Gorontalo, we find this species in muck diving areas.

Similar is the Reef stonefish (Synanceia verrucosa), which is typically found near reefs. It lacks the boney eye ridge and often is more colorful. On our Honeycomb dive site, we find Flasher scorpionfish (Scorpaenopsis macrochir)

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, which is much smaller than Estuarine stonefish. Its body is smoother and usually lies flat with its tail stretched straight back among rubble. Lying in plain sight, it is still most difficult to detect. Another similar venomous bottom dweller is the Devil scorpionfish (Scorpaenopsis diabolus). We sometimes find this fish in muck diving sites. Its skin is almost smooth looking. When disturbed, it stretches out its yellow and red banded dorsal fins, as it glides to another place.

Advice for Viewing

When divers are enjoying muck diving, they should always avoid laying on the substrate. Many creatures live just under the surface. When threatened, they sting in self-defense. Using a dive stick for positioning is a helpful and safe way to observe marine life without making contact with the ocean bottom, something that can be potentially harmful.

Sometimes, the Estuarine stonefish will be sitting in the open, above the sand. Even so, divers will probably swim right past it since it looks like an ugly stone. Careful inspection will reveal the grumpy curve of its mouth, its wide pectoral fins touching the sand, and its tail curled around its body. Hard to spot are its eyes, which are staring at you.

For your chance to see this stonefish in Gorontalo, please make your dive reservations directly with Miguel’s Diving.

Flower urchin trembles with danger

Posted on September 13, 2023 by Miguel's Diving • 0 Comments

Flower urchin looks like a lovely ball of trembling flowers. However, those flowers contain highly toxic venom. This sea urchin’s maximum diameter is about 15 centimeters. It lives in areas of sand and rubble along coral reefs. It also inhabits areas of sea grass.

Beauty to Avoid

Although commonly known as the Flower urchin, the scientific name of this echinoderm is Toxopneustes pileolus. The genus name Toxopneustes means “poison breath.” And “skullcap” is the meaning of pileolus

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, the species name. These names underscore the creature’s deadly possibilities.

Its toxins can cause a number of symptoms. These include breathing problems, muscular paralysis, and numbness. Such effects can render the victim disoriented. The combination can result in accidental drowning. Initial contact gives the victim an extremely painful shock. Then numbness and spasms start to travel through the body from the point of contact. Happily, accidental contact with this sea urchin is extremely rare.

Deceptive Flowers

Various projections cover a Flower urchin’s exposed surface. The most noticeable are the flower-like pedicellariae. These colorful appendages are actually jaws. Each jaw has three prongs. Moreover, the flower-like jaws have sensors that detect contact or proximity movement to the sea urchin. Any touch will trigger the jaws to contract. Then the jaws inject venom. To make matters worse, once the jaws are triggered, they can easily break free from the sea urchin. That means they stay embedded and will continually inject venom for several hours.

The flowers of this sea urchin can appear a pinkish or yellowish white. There will be a single lavender dot in the middle. These false flowers typically cover the short spines of the urchin.

On the underside of the Flower urchin are double rows of tubular feet. These emerge along the ten segments of the urchin’s shell. In the center is the creature’s mouth, which contains five plates. These plates function as teeth that crunch food. Sea urchins forage along the bottom on algae, bryozoans and detritus. With the mouth facing the substrate, the anus faces the water column and any curious passing diver.

Flower Urchin Piled with Debris

To observe a Flower urchin, divers must keep a safe distance. Careful observation of the surface of this creature shows thin, translucent, and waving appendages that are longer that the trembling flowers of the urchin. These appendages are tubular feet that end in three claws. These are used to clear the urchin’s surface of debris.

However, the urchin also uses these tubular feet to move debris from the substrate onto its top and sides. Scientists call this covering or heaping behavior. The tubular feet keep debris in place. The function or purpose of this behavior remains a mystery. Because divers think that a small heap of debris is simply rubble, most flower urchins remain unnoticed.

In the rare instances when we see a Flower urchin, our dive masters will warn guests first and then carefully show the beautiful creature. Afterwards, the dive master will use his stick to move debris on top of the urchin. This helps the urchin but also prevents accidental contact by anyone else passing by.

To dive with such caring dive masters, please make your trip reservations directly with Miguel’s Diving.

Beach Clean Up 2023

Posted on August 28, 2023 by Miguel's Diving • 0 Comments

Beach Clean Up 2023 took place on this year’s International Whale Shark Day. That date was the twenty-seventh of August. The provincial government organized the event at Botubarani Village in Bone Bolango Regency. The location is about twenty minutes from the center of Gorontalo City.

Local Diving Community in Action

In additional to trash removal along the coastline, the government sponsored underwater activities. Over forty local divers participated. Miguel’s Diving staff of five dive masters composed one of the teams. Each team received a couple of used, large rice sacks to collect trash found underwater.

beach clean up 2023 — Coral ready for transplantation

In addition

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, each team received broken corals found at adjacent sites along with ties. Team members tied the coral to a row of bicycles that have been part of an artificial reef. These bicycles sit in a sandy area between coral pinnacles.

Beach Clean Up 2023

Gorontalo dive pioneer and Miguel’s Diving staff Rantje was asked to address the officials overseeing the event. In his remarks, he recounted how the beach clean up 2023 was the latest in an annual series. Year by year, the amount of trash found has decreased.

Looking at the ocean surface that day, he challenged official to see any floating plastic. There was none, even though Beach Clean Up 2023 had not started. This points to the growing awareness of locals to place trash in designed bins. Clearly, no one had thrown trash into the ocean recently.

Local media interviewed Mr. Aryanto Husain, Head of Gorontalo Provincial Tourism Department. He emphasized that this event “improves the attractiveness for both international and national visitors.”

Miguel's Diving staff — Miguel’s Diving staff in action

Additional Activities

In addition to trash pick up above and below the water, Beach Clean Up 2023 included an underwater photo competition. Photos taken served as documentation of the effort. Also, children enjoyed a coloring contest.

Best of all, ladies from Botubarani village had a special area where they sold local food. One favorite is yellow rice, wrapped in a banana leaf.

This year’s event occurred in late August, at the worst of wave season here. Diving season in Gorontalo is from November to April. So, please make your dive reservations directly with Miguel’s Diving. We have been keeping the underwater world here clean for your enjoyment!