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

Loading content - please wait...

Category Archives: Marine Life

Risso’s Dolphins Sunbathe and Play

Posted on March 11, 2025 by Miguel's Diving • 0 Comments

Risso’s Dolphins thrive in the deep waters off Gorontalo’s southern shores. One day, we spotted a large, active pod. Using a drone, we watched as they sunbathed, played, and possibly mated.

Ghostly Apparitions

Risso’s Dolphins (Grampus griseus) are a distinctive species of dolphin. They are born gray but become whiter with age. The older one is, the whiter it appears. When passing under the dive boat or swimming nearby, they look like ghostly apparitions.

Their bodies also show visible scarring. Most scars come from fights with other Risso’s Dolphins, while other scars come from bites of deep-sea squid, their main diet. These features make them easy to identify.

Unlike other dolphins, Risso’s have rounded heads and no beak. They also have a crease running from the blowhole down to the upper lip. This unique feature is only visible up close or from a drone’s view.

Drone Video of Risso’s Dolphins

One day, our dive boat was heading to the second dive site when our captain spotted a pod of Risso’s Dolphins. They were sunbathing on the ocean’s surface, which is typical behavior in Gorontalo. Their distinctive white bodies confirmed their identity.

As we watched from a safe distance, one of our Indonesian guests launched his drone. Dr. Reyhan Aditya captured dramatic footage of this large pod. Some dolphins rested on the surface, while others played. One sequence even suggests mating behavior.

Risso’s Dolphins typically grow to three to four meters long and weigh between 300 and 500 kilograms. Clearly, most dolphins in this pod were adults. At other times, we have seen baby Risso’s among them. Usually, we see pods of about ten individuals, but this pod was much larger.

Worldwide Sightings

Risso’s Dolphins live in temperate and tropical oceans worldwide. They prefer deep offshore waters. Sometimes, they swim closer to land or oceanic islands when the continental shelf is narrow. This is true of Gorontalo’s southern coastline. Here, the continental wall of Sulawesi lies just a few meters from shore, plunging to four kilometers deep. This unique geography makes Gorontalo a great place for pelagic encounters.

Antoine Risso, a French naturalist, first described this species in 1812. Later, the dolphin was named in his honor.

For your chance to see unusual marine life in Gorontalo, please make your dive reservations directly with Miguel’s Diving.

Redlined Jorunna Love Triangle

Posted on February 9, 2025 by Miguel's Diving • 0 Comments

Redlined Jorunna nudibranchs made a rare appearance in Gorontalo. During the required safety stop, divers hovered over a patch of sandy rubble as they rested for three minutes. Looking at the sandy bottom, they discovered a cluster of black Long-spined sea urchins, several shy pipefish, and sea stars. Then, in the gentle surge, they noticed a moving, intertwined mass. It was three Redlined Jorunna nudibranchs engaged in group mating!

Love among Redlined Jorunna

Like other nudibranchs, this species is hermaphroditic. This means each nudibranch has both male and female reproductive organs. To fertilize the eggs, sperm must come from another individual.

It seems the three Redlined Jorunna we saw were donating sperm to each other. Nearby, divers noticed a pinkish ribbon of eggs already laid. According to scientific observers, this nudibranch species only appears in the open during mating. Otherwise, they hide in the reef.

Red lines and Fur

The scientific name for this species is Jorunna rubescens because of its reddish lines and markings. Underwater, divers can use additional light to bring out the reddish color.
Like other dorid nudibranchs, Redlined Jorunna have twin rhinophores on their heads and a bushy tuft of gills at the tail. These three parts can be pulled inside the body when the creature feels threatened.

Unique to dorids, fur-like caryophyllidia cover the body of Jorunna rubescens. Tiny spine-like spicules surround these sensory tubercles. Together, they give the body of this nudibranch a velvety appearance. As a result, some observers commonly call this species the Pink Furry Nudibranch.

For additional underwater photographs of Jorunna rubescens, including close-ups of the caryophyllidia, open this link.

Life and Environment

One of the larger dorid nudibranch species, Redlined Jorunna can grow up to 15 centimeters in length. The largest of the three we saw measured about nine centimeters. Jorunna rubescens lives on the seafloor in Indo-Pacific waters, including areas of coral reef and sandy or rocky bottoms like those found we found. For your chance to see unusual marine life in Gorontalo, please make your dive reservations directly with Miguel’s Diving.

Alligator pipefish hunts for lunch

Posted on January 21, 2025 by Miguel's Diving • 0 Comments

Alligator pipefish are rarely seen, despite their size. Even more remarkable is to follow one as it searches for something to eat. Yet that happened one day in Gorontalo – and we have the video to prove it!

A Mangrove Seed or a Blade of Grass

The Alligator pipefish (Syngnathoides biaculeatus) has a long, slender body that mimics a blade of seagrass. Some divers could also mistake it for a floating seed of a mangrove tree. Its body is usually green or brown. This camouflage helps it blend into its habitats. These include seagrass beds, mangroves, and estuaries. Predators and divers have difficulty recognizing one, even though it can grow quite large – up to 50 centimeters in length!

Most pipefish have paddle-like tails. But not Syngnathoides biaculeatus. Its body tapers to a point. That earns it the common name “Double-Ended Pipefish.” However, most divers call it the Alligator or Crocodile pipefish. Although it lacks a true prehensile tail like seahorses, it can bend its tail to form a hook. This allows the fish to hook onto something on the sea floor and remain motionless.

One Hungry Alligator Pipefish

One day in Gorontalo, we made our safety stop in a sandy area. Suddenly, one of our dive masters waved excitedly. He pointed to something floating motionless above the sand. It was an adult Alligator pipefish, measuring about 20 centimeters. While other divers relaxed and lunched above in our dive boat, we grabbed a video camera and followed the pipefish around.

The pipefish ignored us as it slowly surveyed the area. Soon, we noticed it was actually searching for something to eat. First, it swam across the seagrass bed, then among some coral boulders, and finally among clumps of dead Turbinweed. With the noonday sun beating down, it finally spied something to eat.

Syngnathoides biaculeatus Inhales its Food

The Alligator pipefish uses its elongated snout to suck in tiny prey. It likes to eat mysid shrimp and copepods. While on the hunt, a pipefish moves slowly through the water, probing and looking. When it spots prey, it quickly sucks it into its snout with a powerful vacuum-like motion. We caught all of this in our video.

Although we have seen this pipefish since the initial encounter, we cannot know how long it will stay. For your chance to see unusual marine life in Gorontalo, please make your dive reservations directly with Miguel’s Diving.

Striped Barracuda Warily Eye Divers

Posted on December 5, 2024 by Miguel's Diving • 0 Comments

Striped Barracuda schools on Gorontalo’s shallow reef flats. Smaller and more cautious than its larger relatives, this species dazzles with its streamlined body.

How to Identify Striped Barracuda

In contrast to other barracuda species, the Striped Barracuda is smaller, reaching about 55 cm in length. Also, its body features two thin, dark horizontal stripes running along its silvery body. These stripes are its defining feature and help divers distinguish it from barracudas that look similar.

Sometimes, it is called the Obtuse Barracuda, which translates its Latin name of Sphyraena obtusata.

Other Barracudas found in Gorontalo

Occasionally, divers in Gorontalo will see a Great Barracuda (Sphyraena barracuda). As the largest barracuda species, it can grow over a meter in length. Often, it swims alone. Its imposing size and solitary nature make it easy to differentiate from the smaller, schooling Striped Barracuda.

Also found in Gorontalo is the Yellowtail Barracuda (Sphyraena flavicauda). As its name suggests, its yellowish tail is the most prominent feature. Its body has faint spots instead of the distinct stripes seen on the Striped Barracuda.

The Black Barracuda (Sphyraena qenie) is slightly larger than the Striped Barracuda and is known for its dark fins and body markings. While the Striped Barracuda has clean, horizontal stripes, the Black Barracuda’s markings can appear as a combination of dark smudges and irregular lines, giving it a more shadowy appearance. These features, along with its tendency to inhabit deeper waters, help divers tell the two species apart.

Habitat and Behavior

striped barracuda school — *Sphyraena obtusata* school in Gorontalo

This barracuda species is found in warm, shallow waters throughout the Indo-Pacific region. They prefer areas with coral reefs, mangroves, and seagrass beds, where food is abundant.

During the day, they form schools for protection, creating a shimmering spectacle as light reflects off their bodies. At night, they disperse to hunt small prey like fish and crustaceans.

Tips for your Encounter with Barracuda

The schooling behavior of the Striped Barracuda is a visual treat for divers. Seeing these sleek fish glide in unison over Gorontalo’s colorful reefs is unforgettable.

barracuda wary of divers — Barracudas are wary of divers

However, their cautious nature makes observing them tricky. We suggest divers move slowly, so as not to startle them. Also, try to approach from different angles. The barracuda school will maintain distance from divers if it feels threatened.

An encounter with a school of Striped Barracuda offers divers an opportunity to appreciate the beauty and diversity of the underwater world. So, plan your dive with Miguel’s Diving to explore Gorontalo’s vibrant marine life up close.

Phyllidia elegans decorates reefs

Posted on November 14, 2024 by Miguel's Diving • 0 Comments

Phyllidia elegans is a dorid nudibranch found occasionally on Gorontalo’s coral reefs. Oftentimes, divers see it among rubble. We call it the Elegant wart slug.

The Showy Peaks of Phyllidia elegans

This elegant wart slug has distinctive whitish to pinkish protrusions. These are called tubercles. They look like snowy mountain peaks. A few tops of those tubercles are yellow. This is a distinguishing characteristic of Phyllidia elegans.

Irregular black lines look like rivers running in the valleys between peaks. Some blackish spots can appear along the slug’s edges. Also, for this elegant wart slug, yellow rhinophores are distinctive.

Although divers rarely look at the underside of the slug’s foot, Phyllidia elegans has a median longitudinal black line on its sole. Uniquely, this slug also has black lines on the sides of its foot.

Rare photographs of the Elegant wart slug

The archived website of Sea Slug Forum has several unique photographs of Phyllidia elegans. One shows the gills, which are underneath this critter, between its foot and mantle. Another photo shows the Elegant wart slug laying eggs. The moderator notes this may be the first photo of the egg mass. Moreover, one of the photos is from Gorontalo, taken and submitted by one of our diving guests.

Unknown Life Cycle

Scientists know little about the life cycle of Phyllidia elegans. It is a simultaneous hermaphrodite. That means a single individual is both male and female at the same time. When two of these wart slugs come together for mating, each with stab its penis at the other. The first one to penetrate the other’s skin will be the male for that coupling.

Most phyllidiid nudibranchs, like the Elegant wart slug, feed on sponges of the Phakellia genus. These are usually red-orange in color.

Phyllidia elegans lives in the Western Pacific and Indian oceans, as well as in the Red Sea. Its maximum length is about five centimeters. Divers are more likely to spot it in shallow waters where hard coral growth is poor. For your chance to see this elegant marine critter in Gorontalo, please make your dive reservations directly with Miguel’s Diving.

Razorfish keep their noses down

Posted on September 20, 2024 by Miguel's Diving • 0 Comments

Razorfish and shrimpfish swim in synchronized groups. Typically, they keep their noses down. They are a graceful sight for divers to enjoy.

Distinctive behavior & appearance

These fishes look like flattened razors. Their bodies are light in color with a dark body line. This line reaches from their long noses all the way to the back. Also, the line passes over the eye.

Most distinctive is their swimming pattern. Divers can see them in occasional pairs. Most often, however, they will gather in large schools, forming a shimmering curtain. Usually, they keep a cautious distance from scuba divers. When they decide to move, all the fish in a school will point their noses in the same direction and swim quickly away. Then, they will settle back to their head-down position.

Found through the Indo-Pacific and Indian oceans, they typically live at depth between two and fifteen meters. They tend to prefer areas with some potential for silting. They eat mysid shrimps.

The Razorfish common in Gorontalo

Centriscidae is a small family of fishes that tend to swim with their heads pointed downwards. They all look practically the same. There are two genera: Aeoliscus and Centriscus.

Centriscus scutatus is the species common in Gorontalo. Its common name is Grooved razorfish. This is because the fish has an interorbital groove. That is a narrow depression that runs between its eyes and along the skull. Only scientists in a laboratory can observe this.

Most helpful is for divers to observe the fish’s tail. Actually, what looks like the tip of the tail is the fish’s first dorsal spine. It lies flat along the top of the body and projects beyond the actual tip of its tail. To divers, the fish appears to have a long, thin, and rigid tail.

Confusing similarities

The fish most likely to be confused with the Grooved razorfish is Aeoliscus strigatus. Divers usually call this the Coral shrimpfish. Other common names include Jointed razorfish, Striped shrimp fish, and variations of those words. Careful observers look for the only visible distinctive of this species. This fish has a hinge on the end of its dorsal spine, which swings to the side as the fish moves. It functions like a rudder.

The largest of the shrimpfishes is Centriscus cristatus. It lacks the hinge and its stripe is yellowish with several perpendicular dashes above the stripe. We have not observed this fish in Gorontalo.

The fourth shrimpfish is Aeoliscus puntulatus. In addition to the hinged tail, it sports fine black spots above and around the mid-lateral stripe. We have not observed this species in Gorontalo.

The popular generic name shrimpfish comes from all the bony plates that compose the bodies of these razor-shaped fishes.

For your chance to see these beautiful fish in Gorontalo, make your dive reservations directly with Miguel’s Diving.

Schooling bannerfish found near pinnacles

Posted on August 30, 2024 by Miguel's Diving • 0 Comments

Schooling bannerfish are a rare sight in Gorontalo. Divers can see these beautiful fish at only two less-dived sites.

Trailing white ribbons

Like graceful dancers pulling long, white ribbons behind them, Schooling bannerfish are a distinctive addition to any dive site. The adult fish’s white dorsal fin extends past its tail. This looks like a long banner trailing behind the fish as it swims. Actually, this banner is only the first rays of its dorsal fin. The remaining dorsal fin is thick, deep yellow, and hugs close to the body.

Overall, the fish’s body is white, tall, and flat. It sports two large black bands. These bans cross the body diagonally. Also, the tail and pectoral fins are yellow. The fish’s snout contains a few dark spots.

Schooling bannerfish in Gorontalo

Although this fish lives through Indo-Pacific waters, divers in Gorontalo are not likely to see it. Schooling bannerfish only live in two dive sites here. These sites are rarely visited, and only Miguel’s Diving staff know where to find them. The rarity of this beautiful fish is one of the marine mysteries of the area.

In Gorontalo, this fish stays close to certain coral pinnacles. As ocean currents flow past the pinnacles, these bannerfish feed on passing plankton. As the common name suggests, Schooling bannerfish swim in schools.

Confusing, similar species

Although Schooling bannerfish have unmistakable features, determining the exact species is difficult. Moorish idols also have trailing white dorsal rays. However, they stay in pairs and close to coral rich reefs where they feed on coral polyps. They also have an unmistakable, bright orange patch on their snouts.

Bannerfish with long dorsal fins come in two seemingly identical species. They are Heniochus acuminatus and Heniochus diphreutes. In H. acuminatus, the rear edge of its anal fish is more rounded. In H. diphreutes, the rear edge of the anal fin aims almost straight down, coming to a sharp point. That sharp point is basically half white and half black. Moreover, H. diphreutes has a rounder face and generally feeds on plankton in the water column. H. acuminatus tends to feed nearer the substrate, have a longer snout, and can travel in pairs or even alone.

Both species have numerous common names. One common name for H. acuminatus is the Longfin bannerfish. Its other names are Pennant coral and Reef coachman. H. diphreutes is usually called Schooling bannerfish.

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

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.