Diving with Thick-arm Jellyfish
Lanta Marine Life | Catostylidae
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)
Crambione mastigophora @ Koh Haa
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.
Diving with Thick-arm Jellyfish around Koh Lanta
Scuba Diving & Snorkel Trips
If you'd love a chance to spot Thick-arm Jellyfish on one of our daily high season diving trips from Koh Lanta then send us an email to info@diveandrelax.com.
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Find Out More
Indo-Pacific Marine Life Guides
- Allen, G., Steene, R., Humann, P., DeLoach, N. (2003) Reef Fish Identification, Tropical Pacific. Jacksonville, FL., USA: New World Publications, Inc., ISBN 1-878348-36-1.
- Humann, P., DeLoach, N., (2010) Reef Creature Identification, Tropical Pacific. Jacksonville, FL., USA: New World Publications Inc., ISBN 978-1-878348-44-9
- Debelius, H. (2013) Indian Ocean Reef Guide. Frankfurt, Germany: IKAN - Unterwasserarchiv, ISBN 978-3-939767-52-7.
- Debelius, H. (2004) Nudibranchs and Sea Snails, Indo-Pacific Field Guide. Frankfurt, Germany: IKAN - Unterwasserarchiv, ISBN 3-925919-51-1
- Erhardt, H., Knop, D. (2015) Corals Indo-Pacific Field Guide. Frankfurt, Germany: IKAN - Unterwasserarchiv, ISBN 3-925919-69-4.
- Veron J.E.N., Stafford-Smith M.G., Turak E. and DeVantier L.M. (2016). Corals of the World