Box Jellyfish Venom

Box Jellyfish are one of the deadliest types of jellyfish in the world. Like most jellyfish, they use venom to hunt prey and defend themselves against predators. In Australia, they are found from Gladstone to Broome and have caused more than 80 deaths since 1900. They have a pale blue, cubic shaped bell that grows up to 20cm high and 25cm wide, and weighs up to 6 kilograms. Box jellyfish have four eye spots- each positioned on a corner of their bell - that are attracted to light. The jellyfish then propels itself by ejecting water from the body cavity. By varying the position of the body cavity opening, the jellyfish can change direction (Sutherland & Nolch, 2000).

A box jellyfish (Image 1).

Box jellyfish anatomy (Image 2).

The venom apparatus of a box jellyfish is its tentacles, which can grow up to 3 metres. The tentacles are attached to four pedalias (fleshy arms) on the bell. There are approximately 12000 stinging capsules per square millimetre of the tentacle, adding up to millions of nematocysts. The nematocysts (which are like little torpedos filled with venom) are discharged with great force and are then screwed deep into the skin of the victim upon contact. These threads are 0.2cm long, allowing them to reach through the skin and into the capillaries and other vessels of the body. This leads to a massive absorption of venom. The tentacles also have a second type of capsule that produces a gluey substance that helps the tentacles to stick to prey. For hunting purposes, the death of the prey (usually a prawn or fish) is instantaneous. This prevents harm coming to the jellyfish (Sutherland & Nolch, 2000). 

The box jellyfish's venom has three separate components. The first component is dermaatonecrotic, meaning it causes rapid skin death. The second component has a high molecular weight toxin, which is responsible for the cardiovascular collapse and respiratory failure. The third component produces mild haemolusis (the destruction of red blood cells) and elevates the potassium levels in the blood stream, causing an abnormal heart beat (Sutherland & Nolch, 2000). 

When humans are stung, the pain increases in waves for the first 15 minutes. Areas that come in contact with the tentacles become purple or brown. Healing can take up to a month or more and may leave permanent scars. In severe cases, consciousness is lost after the victim is stung and death occurs after a few minutes. It is also quite probable that the victim will die if there are more than 6 to 7 metres of weals (wounds from the tentacles) on the body. An antivenom has been developed, and after 90 seconds of injection, the pain and skin lesions reduce (Sutherland & Nolch, 2000). 

The necrosis of skin after a box jellyfish skin (Image 3).

References

Sutherland, S., & Nolch, G. (2000). Box Jellyfish. Australasian Science , 21 (8), 39-41.

Images

Image 1 - 

http://graphics8.nytimes.com/images/2012/12/18/science/18OBFOSSIL/18OBFOSSIL-articleLarge.jpg. Accessed on 28/3/14.

Image 2 - http://smithsonianscience.org/wordpress/wp-content/uploads/2012/02/box-jellyfish-diagram.bmp. Accessed on 28/3/14.

Image 3 - http://deepseacreatures.org/images/stories/jellyfish-sting-box.jpg. Accessed on 28/3/14.