• 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: 2019

Dogtooth Tuna Video

Dogtooth tuna video recently shot in Gorontalo is now available for viewing.

Tuna on the Reef Edge

Although Gorontalo is famous for its Yellowfin tuna, the tuna that divers will most likely see here is Dogtooth. This tuna is one of the apex predators like Giant trevally and large groupers.  They eat smaller schooling fish that thrive off Gorontalo’s coral walls. These include fusiliers, fairy wrasses, scads and rainbow runners. As evidenced in the Dogtooth tuna video, these fish are curious about divers. As a result, they will often make several passes, giving time for visitors to get cameras ready.

Lucky Dogtooth Tuna Video

A prime dive site for viewing larger schooling fish is Buffalo Head Point.  It numbers among Gorontalo’s many submerged points. These points jut away from the cliff above water and away from the underwater coral wall. Moreover, this position interrupts the smooth flow of the area’s longshore current. When a strong current is running, schooling fishes will congregate off these submerged points.

On the day this Dogtooth tuna video was shot, the current was moderately strong. Also, the plankton count was high. Notice all the backscatter in the video. That is living plankton. As a result, schooling fish that feed on plankton gathered in abundance. Notice the Blue-and-yellow fusiliers in the video. This is the kind of fish that fast swimming Dogtooth tuna love to eat.

Although dive staff often see large fish in these conditions, everyone was surprised with the close encounter with schooling Dogfish tuna.

Tuna without Scales

The scientific name for Dogtooth tuna is Gymnosarda unicolor. Unlike other sarda, this one lacks scales. Hence its official name, since gymno means “naked” in Greek. This silvery fish is considered unicolor, in contrast to other tunas like Yellowfin or Bluefin. It sports a single, undulating lateral line.

dogtooth tuna video
A Dogtooth tuna cruises in Gorontalo

Divers can easily recognize this streamlined fish. It has white tips on its upper and lower back fins. The caudal peduncle also shows a white area. These white markings are clearly visible in the Dogtooth tuna video. Also, notice that the fish’s upper jaw extends even with its eye. This fish swims with its mouth open, showing its many conical teeth.  

The average size of Dogtooth tuna that divers see swimming along Gorontalo’s coral walls is between 40 to 120 centimeters. Mature fish can measure up to two meters in length and weigh up to 120 kilograms. These swim in depths as deep as 300 meters. Miguel’s Diving staff estimate the larger ones seen in the Dogfish tuna video weighed about 50 kilos!

This tuna species lives in tropical waters of the Indo-Pacific region.

For your chance to see Dogtooth tuna in Gorontalo, please book your dive trip with us!

Thysanoteuthis rhombus egg masses

Thysanoteuthis rhombus egg masses are rarely seen. However, one of them drifted near Miguel’s Diving speed boat during a surface interval. It looked like a giant pink and transparent version of a child’s slinky toy.

Thysanoteuthis rhombus egg masses

Thysanoteuthis rhombus egg mass floats on the surface

Thysanoteuthis rhombus egg masses

Mysterious, deep water squids lay eggs in spirals. A gelatinous case holds the long spirals together. After the fertilization process is complete, the egg mass will float with ocean currents near the surface.

Thysanoteuthis rhombus egg masses can measure up to 1.8 meters in length. Each tiny pink pearl is actually a squid egg. A single egg case carries between 24 and 43 thousand eggs inside its transparent case. The egg mass the Miguel’s Diving staff discovered measured about one meter.

diamond squid egg mass detail
Detail of diamond squid egg mass

Thysanoteuthis rhombus egg masses drift with strong currents in warm tropical waters. Seeing them is indeed a rare event. This occurrence marks only the second time Miguel’s Diving staff have discovered this type of egg mass during our 16 years of operation.

Diamond Squid from the Depths

This deep water squid is sometimes called diamond or diamondback squid. It has distinctive fins that run its body length. Its scientific name, Thysanoteuthis rhombus, describes its rhombic shape. Its arms are noticeably short. However, it can grow up to 100 centimeters and weigh up to 30 kilograms.   

This diamond quid lives in the deeper parts of the ocean during the day. Trawlers have found it at depths below two kilometers! Since Tomini Bay, where Miguel’s Diving operates, plunge to twice that depth, no one should be surprised to learn deep sea squid live in Gorontalo waters. At night, it will rise nearer the ocean surface. It is found worldwide in tropical and subtropical seas.

The beautiful Thysanoteuthis rhombus egg masses come from mating pair. The diamond squid are the only cephalopod known to remain in the same mating pair for life. Fishermen observed that if one of the pair is caught, its mate will remain in the area until it is caught as well. Diamond squid naturally live about one year.  

Thysanoteuthis rhombus sketch

Thysanoteuthis rhombus adult

Deep Water Encounter

This squid is fished commercially in Japan. Other predators include tuna, swordfish, sharks, Rough-toothed dolphins, as well as False Killer and Sperm whales. Miguel’s Diving staff have observed all of those predators in the Gorontalo waters of Tomini Bay.

Although divers are unlikely to see these deep water Thysanoteuthis rhombus egg masses anywhere in the world, our guests often see other pelagic species. For your chance to meet deep water marine life in Gorontalo, please book your dive trip with us.

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