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

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Yearly Archives: 2024

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.