• 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: Marine Life

Funnelweed pass unnoticed

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.

funnelweed
Beautiful white funnelweed in Gorontalo

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.

Padina gymnospora
Padina gymnospora clings to a wall

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

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

Duncanopsammia peltata
Corallites 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.  

pagoda coral
Photo courtesy of @jhonheriano

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

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

Dendrodoris tuberculosa
The first 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 Tuberculate Dendrodoris

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.

Dendrodoris tuberculosa
The third sighting

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

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.

dead nudibranch
Dorsal side of the dead nudibranch

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

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

sargassum frogfish
Sargassum frogfish hides among weeds

One such predator is the Sargassum frogfish. Like other frogfish

, 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

frogfish
Floating on surface weeds

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.  

Flower urchin trembles with danger

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

flower urchin
Flower urchin hiding in the reef

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

, 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.

Toxopneustes pileolus
Appendages of Toxopneustes pileolus

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.  

Fin whale startles crew

Fin whale surfaced right next to one of our staff while he was fishing for yellowfin tuna. Tomini Bay where we dive is over four kilometers deep. So, large cetaceans are part of the marine environment in Gorontalo.

Surprise Encounter

Boka, one of Miguel’s Diving dive masters, headed to deep waters offshore. On his day off, he decided to fish for yellowfin tuna. Local fishermen use traditional handlines. This method is ecologically sustainable.

Identification book for whales

Suddenly, a large whale surfaced only a few meters away from his outrigger canoe. Then the whale exhaled, sending spray into the air.

Boka’s outrigger canoe measures five meters in length. He estimates the fin whale that surfaced next to him to be twelve meters. That means this particular whale was still small. Adult fin whales can reach 22 meters in length. This species is the second largest animal on planet earth, after the larger Blue whale. The cetaceans we see tend to be young. That includes whale sharks, orcas, and whales. It seems that the deep waters of Tomini Bay are a prime location for young cetaceans to grow into adults.

Fin Whale in the Southern Hemisphere

Although fin whales live in all the world’s oceans

, they are mostly sighted in the southern hemisphere. When a fin whale surfaces, its dorsal fin appears right after the whale blows. The dorsal fin is quite small and points backwards. Its flukes are rarely visible. Most notable, it is large size. Also, fin whales ignore boats. This is what happened when Boka encountered one.

Fin whale sketch (c) NOAA

The fin whale used to be hunted commercially. This is now banned. As a result of over hunting, this species is considered endangered. The population of the southern hemisphere has been particularly slow to recover. Balaenoptera physalus is the scientific name.

Fin whales are filter feeders. Those in the southern hemisphere feed almost exclusively on krill. They can also eat plankton, small schooling fish, and squids. Their only known predator is the Orca or killer whale. In Gorontalo we see orca annually, usually in January and February.

Although scuba divers are not likely to see a fin whale in Gorontalo, whale shark sightings are common. So, please make your dive reservations directly with Miguel’s Diving.  

Yellow lace coral lives deep down

Yellow lace coral thrives below thirty meters in Gorontalo. Its bold honey-lemon hue adds distinctive color to deep reefs where ambient light is low.

Not a Reef Building Coral

Although they have some similarities, lace corals are not fire corals. Millepora fire coral species have symbiotic algae living inside their tissues. These algae contribute nutrients and color to fire corals, as well as reef building corals.

yellow lace coral
Deep water Yellow lace coral

However

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, lace corals are hydrocorals. Their skeleton is made of calcium and can easily break. Its tiny polyp pores are minute with diameters less than one millimeter. Lace corals have two genus, Stylaster and Distichopora. They lack symbiotic algae. This means that the distinctive colors of lace corals are part of their skeletons. Whereas other coral skeletons turn white when the colony dies, lace corals retain their coloration even after death.

Yellow Lace Coral & Deep Reefs

Divers in Gorontalo who venture down to thirty meters can easily spot Yellow lace corals on certain dive sites. These corals look like yellow fans. Sometimes, a colony has more than one fan from the single base. The branches are stout and rounded. Gorontalo’s Yellow lace corals have tips of white. They are found on vertical surfaces and tucked into small holes or crevasses.

The Yellow lace coral could be Distichopora violacea, despite not being purple. There are 34 named species of Distichopora, but many remain unnamed. They are only found in Pacific oceans, including Tomini Bay where we dive.

Tiny, Stinging Hairs

Distichopora stinging cells
Stinging hairs of Yellow lace coral

Like other Distichopora species but unlike reef building corals, our Yellow lace coral has different types of polyps. All connect via canals inside the yellow skeleton where they are imbedded. These microscopic polyps have different functions. Two types protrude from the skeleton. They are gastropores and dactylopores.

The dactylopores have fine hairs that possess stinging cells called nematocysts. They can leave stings on divers who touch or brush against them. The function of these cells is to sting plankton. The stunned plankton are then eaten by gastropores, which contain the feeding polyps.  

Complex Reproduction of Lace Corals

Distichopora cf violacea
Multiple Yellow lace coral colonies

Although reproduction among reef building corals is relatively straightforward, that of lace corals is not. Lace coral polyps release medusae, which look like microscopic jellyfish. These medusae possess both male and female reproductive organs. These in turn release eggs and sperm into the ocean. A fertilized egg will develop into a larvae that swims until it reaches a hard surface. There is will attach and form a new lace coral colony.

Lace corals can also reproduce by fragmentation. For your chance to see Gorontalo’s deep water Yellow lace coral, please make your dive reservations directly with Miguel’s Diving.  

Leopard sea cucumber self-mutilates

Leopard sea cucumber is a beautiful creature of the ocean floor. However, divers should avoid touching its sensitive body.

Spotted Beauty

The Leopard sea cucumber lives in the eastern Indian and the western Pacific oceans. In the areas we dive in Gorontalo, it can only be found dependably at a single dive site. This sea cucumber lives in sandy areas, flanked by coral reef. Researchers say that it lives from three to almost forty meters deep. We usually find it between 15 and 18 meters here.

Leopard spots
Close-up of spots

Although research claims it can grow to 60 centimeters, those in Gorontalo measure only half of that length. Divers can easily identify the Leopard cucumber. Its spotted pattern is distinctive and unmistakable. The tubular body is grey but sprinkled with random rows spots. These spots are orange and edged in brown.

Avoid Touching

Leopard sea cucumber is highly sensitive. It considers touching, grabbing, or lifting to be a threat. When threatened, it will eject white strings. These elongate in sea water. They also become sticky. Scientists consider this behavior to be defensive.

These white strings are called Cuverian tubes after the French zoologist who first studied them. They are naturally attached to the sea cucumber’s interior respiratory system. When the Leopard cucumber feels threatened, it will contract its body muscles. This contraction is so great that it tears the cucumber’s interior. The contraction forces Cuverian tubes out of its anus. In this way, it self-mutilates.

Leopard sea cucumber
A Leopard sea cucumber sits undisturbed

The Leopard sea cucumber can regrow its tubes. However, this takes several weeks. So, divers should avoid touching this sea cucumber. The tubes contain toxins, which can cause skin irritation in humans. Interestingly enough, researchers are using toxins from the Leopard sea cucumber in cancer research.

Leopard Sea Cucumber in Ecology

This sea cucumber has several rows of tubular feet on its underside. It moves slowly across the sandy bottom. While doing so, it ingests sand and anything the sand contains. In this way, all sea cucumbers clean the ocean floor of detritus and other waste materials.

Moreover, its own waste is beneficial to coral growth. After internal digestion, it excretes calcium carbonate and ammonia along with clean sand.

Home for a Fish

Pearl fish live inside of some Leopard sea cucumbers. The fish’s scientific name is Carapus mourlani. It enters and exits the cucumber via the anus, usually tail first. A scientific study in Indonesia of Bohadschia argus, the official name for the Leopard sea cucumber, found fifteen pearl fish living inside a single cucumber!

Sometimes an Emperor shrimp will be living on the sea cucumber’s surface.

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

Arothron caeruleopunctatus pufferfish hiding in plain sight

Arothron caeruleopunctatus is a large pufferfish that hid in plain sight until a Japanese researcher named it in 1994.

Not the Other Blue-spotted Puffer

Scientific names are always best to identify marine life. Although the name of the large puffer Arothron caeruleopunctatus means “blue-spotted,” another small pufferfish is often called the Blue-spotted puffer. That fish is a small toby named Canthigaster solandri. It has various blue spots and a colorful body. An internet search for a blue spotted puffer will produce photos for C. solandri, not A. caeruleopunctatus.

Arothron caeruleopunctatus
Arothron caeruleopunctatus along a deep wall

Arothron caeruleopunctatus can measure to 80 centimeters in length. That makes this species one of the largest pufferfishes worldwide. Divers giving it a casual glance would find it uninteresting. Its body is primarily dull with hues of gray and dark blue. Ventrally, it is often white. Dorsally, it can have a yellow, irregular blotch. The fish’s scientific name comes from the numerous blue to white spots found on its body. These are round to rice shaped. Also, concentric lines circle the fish’s eyes.

Unnoticed until 1994

Divers assumed that this oval-shaped fish was one of the other large puffers that live in Indo-Pacific waters. However, in 1994, Dr. Keiichi Matsuura published his finding of this pufferfish that had been hiding is plain sight. Dr. Matsuura is curator emeritus at the zoology department of the Museum of Nature and Science in Tsukuba, Japan.

In addition to Arothron caeruleopunctatus, he has discovered and named other pufferfishes. These include Arothron multilineatus (2016) from Ryukyu Islands, Japan, and Chelonodontops alvheimi (2018) from Myanmar. Also, he named a new Fugu puffer, Takifugu flavipterus (2017) from Japan, Korea, China, Taiwan, and Far East Russia. Another pufferfish he named is Canthigaster aziz (2020) from the northern Red Sea off Saudi Arabia.

Arothron caeruleopunctatus in Gorontalo

Divers can see this Blue-spotted puffer occasionally along Gorontalo’s coral reefs and deep walls. Like other large pufferfishes

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, it is quite shy around divers. Careful approach can reward a patient diver with a clear view of the blue-spotted pattern of this fish. It lives from two meters to below safe diving limits.

blue spotted puffer
Smile for the camera!

A close look reveals that its skin lacks scales. Also, its dorsal and anal fins are small. These are located towards the back of its body and are symmetrical. Moreover, it lacks a pelvic fin. Its short snout has two pairs of nostrils. It feeds on invertebrates that live on the substrate. To feed, it uses its four strong teeth. This pufferfish is active during the day.

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

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