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Diving with Thick-arm Jellyfish

Koh Lanta Marine Life | Catostylidae
Spaghetti WormsRequiem Sharks

The thick-arm or 'fat-arm' jellyfish are a family of over 20 jellyfish species, often drifting past the islands and dive sites around Koh Lanta.

These jellyfish have domed bells reaching upward of 40 cm in diameter. Members of this family have eight short arms surrounding the mouth. The arms are three-sided.

These jellyfish swim in jerks by contracting their circular and radial muscles,. They have no control over the direction of locomotion and drift with the currents.

1 species found on this page.

Sea Tomato

(Crambione mastigophora)

Sea Tomato (Crambione mastigophora) @ Koh Haa

Crambione mastigophora @ Koh Haa while diving from Koh Lanta

The Sea Tomato is one of eight edible jellyfish species found in the eastern Indian Ocean.

This species can weigh up to 2.8 kg and the umbrella can reach 27 cm in diameter. There are eight main arms, each with 8 - 11 marginal lappets (hanging pieces of flesh). Each marginal lappet is relatively wide, with a rounded margin.

The Sea Tomato has 8 mouth arms which are the same, or slightly longer than the umbrella diameter.

Each mouth arm has several appendages, numerous long, narrow and filamentous, and a single small, club-shaped appendage.

The Sea Tomato can cause an annoying and painful, but not life-threatening sting.

Koh Lanta Diving with Thick-arm Jellyfish

If you'd love a chance to spot Thick-arm Jellyfish on one of our daily Koh Lanta diving trips then send us an email to info@diveandrelax.com.

Join our high season speedboat dive trips to some of Thailand's best dive sites and enjoy small groups, short journey times, and a focus on great personal service, safety and fun.

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