Avoid Accidents with Jellyfish

Jellyfish are increasing in numbers in our waters, and USM’s researchers get us to the bottom of the matter.

Jellyfish in General

Jellyfish have roamed the seas for at least 500 million years and possibly as long as 700 million years or more – making them the oldest multi-organ animal. They are members of the phylum Cnidaria family and come in a wide range of forms.

The body of an adult jellyfish consists of a bell-shaped hood enclosing its internal structure, from which its tentacles are suspended. Each tentacle is covered with “nematocysts” – a type of venomous cell unique to the phylum Cnidaria which can sting or kill other animals. Jellyfish lack basic sensory organs and a brain; however, their nervous systems and rhopalia (small sensory structures) allow them to perceive stimulants, such as light and current flow, and enable them to respond quickly.

Jellyfish feed on small fish and zooplankton that get caught in their tentacles. Most jellyfish are passive drifters and slow swimmers, as their shape is not hydrodynamic. Instead, they move so as to create a current, forcing the prey to be within reach of their tentacles. They do this by rhythmically opening and closing their bell-like bodies.

Jellyfish are found in every ocean, from the sea surface to the deepest depths. Scyphozoans (“true jellyfish”) are exclusively marine, but some hydrozoans live in freshwater. Large, often colourful jellyfish are common in coastal zones worldwide.

Ribbon jellyfish (Chrysaora chinensis).

Edible sand type jellyfish (Rhopilema hispidum).

Box jellyfish (Chiropsoidis buitendijki).

There are four major classes of jellyfish:

Scyphozoa are sometimes called “true jellyfish”, and have tetra-radial symmetry. Most have tentacles around the outer margin of the bowl-shaped bell, and long, oral arms around the mouth in the centre of the sub-umbrella.

Cubozoa (box jellyfish) have a (rounded) box-shaped bell, and their velarium enables them to swim fast. Box jellyfish may be related more closely to scyphozoan jellyfish than either are to the Hydrozoa.

Hydrozoa medusae also have tetra-radial symmetry. They nearly always have a velum attached just inside the bell margin and do not have oral arms, but a much smaller central manubrium with terminal mouth opening instead. They are distinguished by the absence of cells in the mesoglea. The majority of hydrozoan species maintain the polyp form for their entire life cycle and do not form medusa at all – such as Hydra, which is hence not considered a jellyfish.

Staurozoa (stalked jellyfish) are characterised by a medusa form that is generally sessile, oriented upside down and with a stalk emerging from the apex of the “calyx” (bell), which attaches to the substrate. Some – and perhaps all; it is not known yet – Staurozoa also have a polyp form that alternates with the medusoid portion of the life cycle. Until recently, Staurozoa were classified within the Scyphozoa.

Jellyfish in Penang

Very few studies on jellyfish have been conducted in Penang waters. This field of study was pioneered by Universiti Sains Malaysia (USM)’s Centre For Marine and Coastal Studies (CEMACS), in their research on jellyfish ecology around Penang and on the monthly distribution and abundance of jellyfish species in the coastal waters of the Penang National Park. The study, conducted for 12 months from November 2009 to October 2010, found that jellyfish species abundance does not fluctuate much, and there is no significant trend that allows the fluctuation to be predicted. Excessive nutrient input may be the major factor behind the increased abundance of jellyfish, followed by climate change and human activities.

Morbakka sp.

Five dominant jellyfish species from five different genera were identified in the coastal waters of Penang Island. These are the Australian spotted jellyfish (Phyllorhiza punctata), ribbon jellyfish (Chrysaora chinensis), edible sand type jellyfish (Rhopilema hispidum) and box jellyfish (belonging to Chiropsoidis buitendijki or to Morbakka sp.).

Ribbon jellyfish dominate the Penang jellyfish population and made up 87-95% of the total jellyfish abundance recorded (data collected from 2009-2014). These were detected at all coastal waters around the island and the mainland.

Compositions of other jellyfish species were much less compared to the ribbon jellyfish; the percentage recorded was 4-12%. Although the Australian spotted jellyfish also marked their presence at all survey sites, they only made up 4-9.5% of the total abundance of the sampling period.

Edible sand type jellyfish were the third most widely distributed jellyfish species in Penang’s coastal waters. The abundance of this species was nevertheless extremely low, at less than 1% of recorded jellyfish. The box jellyfish demonstrated a more obvious distribution pattern – the species was recorded at only four sampling sites: Pantai Kerachut, Tanjung Bungah, Tanjung Tokong and Pantai Bersih – and was also low in abundance.

In September last year CEMACS received new funding from the Penang state government to monitor jellyfish species in the coastal waters of Penang. The 18-month project will be conducted at Teluk Bahang, Batu Ferringhi, Tanjung Bungah, Tanjung Tokong, George Town and Pantai Bersih/Robina. The team will study monthly water quality patterns (physical and chemical) and analyse the effects of water quality on the distribution and abundance of jellyfish species.

The final aim is to have a better understanding of the ecological processes determining the outbreaks of jellyfish populations in Penang. CEMACS is working closely with jellyfish experts from Japan, China and Thailand, and is leading a jellyfish monitoring programme in the region under the initiative of IOC-Westpac, which involves 10 countries in the region.

Permanent warning and information signs should be strategically placed at beaches.

Rhopilema hispidum.

Stay Safe!

Box jellyfish are the deadliest jellyfish in the world. Their venom can kill in minutes. They live in tropical seas throughout South-East Asia and Australia, and in other parts of the world including Hawaii, the Caribbean, the Pacific Islands, the Indian Ocean and the Persian Gulf.

Stings – including fatal cases – have been reported in numerous places in Malaysia and Thailand.1 Unfortunately, little is known about where box jellyfish occur in our coastal waters, or if there is a season during which they are more common. Research is minimal; and no one knows for certain which species of box jellyfish is responsible.

Only two species of box jellyfish were recorded at Pantai Kerachut, Tanjung Bungah, Tanjung Tokong and Pantai Bersih throughout the survey, and it is believed that there are still many undiscovered box jellyfish habitats along the Penang coastline.

What is known is that box jellyfish can swim (not float) at a speed of about 3 knots. They are brainless but have a visual system of navigation (eyes with retinas, lenses, corneas) that guides them past obstacles such as rocks, nets and slow-moving human legs. They are almost completely transparent, and hunt for small fish and shrimp in very shallow, sandy-bottom water close to the shore. Encounters are often labelled as jellyfish “attacks”, but all human stings are accidental – it is unsuspecting swimmers who make contact with the jellyfish, and not vice versa.

Scars from jellyfish stings.

Recent newspaper reports on jellyfish attacks.

Late last year, media reports warned of the emergence of box jellyfish in local waters.2 ,3 Jellyfish sting cases in Penang also captured public attention when a 12-year-old boy fell into a coma after being stung in May last year4 ; and when swarms of stinging jellyfish proved to be an added obstacle for participants of the 2015 Penang International Cross Channel Swim.5

People in Penang are generally unaware of the right treatment for box jellyfish stings; and using urine or water to counteract the sting are among the first methods that come to mind. Furthermore, the USM survey team found only two simple jellyfish warning signboards at popular tourist spots on the island (the Penang National Park and Batu Feringghi); and these were not accompanied by first aid information and treatment procedures or instructions.

The USM team believes that permanent warning and information signs, plus vinegar stations, should be strategically placed around Penang's beaches – these have proven to work in Australia and Thailand. There are islands and beaches in Thailand– Phuket, Koh Chang, Koh Mak and Koh Lipe – that have implemented box jellyfish safety systems, with no detrimental effect on their tourist numbers.

Bathing in the sea need not be the peril some might think it to be. Staying informed and carrying a small bottle of vinegar along with you can take you a long way. If stung, you should immediately splash vinegar onto the affected area. Do not try to remove the tentacles. Should the victim require it, use CPR on him or her. Wait for 30 seconds after applying the vinegar before attempting to remove the tentacles – the stinging cells should be de-activated by then, and you can remove them with seawater. Seek immediate medical assistance.

1John M. Lippmann, Peter J. Fenner, Ken Winkel & Lisa-Ann Gershwin (2011). Fatal & Severe Box Jellyfish Stings, Including Irukandji Stings, in Malaysia, 2000–2010. Journal of Travel Medicine, vol. 18, issue 4, pg. 275-281.
2www.thestar.com.my/news/nation/2017/10/08/boxy-terror-set-to-sting-penang-scientists-call-for-cautionas- deadly-box-jellyfish-found-off-states.
4www.thestar.com.my/news/nation/2017/03/07/jellyfish-victim-out-of-coma-boy-unconscious-for-threedays- by-slowacting-toxin-that-shrinks-veins.

Prof. Dato’ Dr Aileen Tan Shau Hwai is director of CEMACS, and executive director of the Asia-Pacific University Community Engagement Network, USM. Her field of expertise is marine science, and she specialises further in mariculture and in the conservation of molluscs. She currently leads a team of experts under the IOC-WESTPAC regional programme in conducting research on jellyfish and drafting a comprehensive plan on dealing with threats caused by jellyfish.
Sim Yee Kwang is a senior science officer at CEMACS. His main research interests are marine and coastal ecology; environmental studies on jellyfish; and echinoderm taxonomy and systematics. He has been conducting research on jellyfish since 2009 and is currently involved in jellyfish monitoring in the coastal waters of Penang (2017-2019).

Related Articles