• Photo by Rantje Allen

  • Photo by William Tan

  • Photo by Rantje Allen

  • Photo by William Tan

  • Photo by Rantje Allen

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Monthly Archives: April 2015

Thysanostoma thysanura Jellyfish in Gorontalo

Thysanostoma thysanura is a large jellyfish rarely seen in Gorontalo waters.

Bushy Oral Arms

Thysanostoma thysanura in Gorontalo
Thysanostoma thysanura surface swimming

This large jellyfish lives in warm waters from the central Indo-Pacific to Japan. It was named in 1880. The Latin word thysanura means “bristle tails.” This name refers to the large, bushy oral arms that hang from the jellyfish’s central bell. Modern researchers have gathered specimens from Sulawesi, the northern Philippines and the Great Barrier Reef in Australia. Thysanostoma thysanura has been seen at depths reaching 24 meters. In Gorontalo, however, it has only been observed at the surface.

Encounter with Thysanostoma thysanura

Although Miguel’s Diving has been operating in Gorontalo since 2003, we have only encountered Thysanostoma thysanura a few times. After a dive in April 2015, one was swimming around the dive boat. Jellyfish of any kind are usually not present in areas where we dive. Imagine the excitement to see this large and beautiful jellyfish. In our experience, this jellyfish is a very active swimmer. It pumps water with its bell to move. Its oral arms drag along behind it. Taking photographs was a challenge because it never stayed still. Watch our video!

Jellyfish Facts

Adult jellyfish are called medusa. They have a soft body consisting of a bell with tentacles or oral arms surrounding a central mouth. Solitary medusa, like Thysanostoma thysanura, swim freely in the open ocean.

 

a rare Thysanostoma thysanura
A rare encounter in Gorontalo

Jellyfish are most famous for the stinging cells contained in their tentacles. The stinging cells are called nematocysts. They are microscopic and sensitive to pressure. Even a causal touch triggers hundreds or thousands of nematocysts. They fire like darts. Jellyfish use them to immobilize prey like small fish.

Some jellyfish are considered dangerous to humans. We have never seen any of these in Gorontalo. Since Thysanostoma thysanura is so large, avoiding it is quite easy. Since this jellyfish is so rare, only a few lucky divers will ever see it. Our jellyfish was kindly identified by Wyatt Patry of Monterrey Bay Aquarium.

Diving in Gorontalo is exciting because of the unusual marine life found here. For your chance to experience the beauty of Gorontalo, please book your dive trip with us.

Porcupine Fish of Gorontalo

Porcupine fish add to the diversity of marine life in Gorontalo. About twenty species of this unusual fish are found worldwide. Divers are most likely to encounter three of them in Gorontalo.

Prickly Balls

Porcupinefishes are similar to puffers. They have distinctive body spines. When threatened, they will ingest water. This dramatically increases their body size and causes their spines to protrude. It is consider bad manners for divers to provoke this defensive behavior. The fish is terrified that it will be eaten.

Black-blotched porcupine fish

Blotched porcupine fish in cave
A Blotched porcupinefish scurries into a cave

The most common porcupine fish found in Gorontalo is the Black-blotched porcupine fish (Diodon liturosus). It is found in tropical waters of the Indo-Pacific region. It is usually about 45 cm in length. Like other porcupinefishes, it eats sea urchins, gastropods and crustaceans. If divers see more than one, it is mating season. Usually, porcupinefishes are solitary. They are also nocturnal. During the day, they prefer caves and sheltered crevasses.

Similar to the Black-blotched porcupine fish is the Long-spined porcupine fish. The only visible difference is that it lacks dark spots on its fins. It is found in warm tropical waters worldwide. Its official name is Diodon holocanthus.

Spot-fin porcupine fish

Spot-fin porcupine fish hides
A Spot-fin porcupinefish hides under a rock

The Spot-fin is the largest porcupine fish found in Gorontalo. Its scientific name is Diodon hystrix. It grows up to 91 cm and is covered with black spots. It is found worldwide. Like other porcupinefishes, certain of its glands contain tetrodotoxin. This is a powerful neurotoxin.

Orbicular burrfish

Orbicular burrfish eye
The eye of an Orbicular burrfish

This small type of porcupine fish grows to only 30 cm. Its official name is Cyclichthys orbicularis. Unlike the others, it is found on sandy or mud bottoms. Divers will see it while muck diving. It prefers hiding in sponges during the day. The iridescent eye of this fish graces the back cover of the book Gorontalo: Hidden Paradise.

Diving in Gorontalo is exciting because of the incredible variety of marine life. To glimpse one of Gorontalo’s porcupinefishes, please book your dive trip with us.

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