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Published on March 24th, 2010 | by Yellow Magpie

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Box Jellyfish: The All-Seeing Creature With 24 Eyes

They may not be as terrifying as the sight of jagged rows of shark’s teeth protruding from the water. They may not carry the same sense of dread as being in a one-on-one situation with a large lion.

They may also not be as horrifying as being confronted with a large venomous snake but they are far more lethal. The Box Jellyfish is one of the most deadly creatures to exist in our seas and oceans.

Box jellyfish (Cubozoans) are remarkable creatures. What initially appears to be quite a simple animal, turns out to something completely different.

Box Jellyfish

A false notion, perhaps used to comfort us, existed that the Box Jellyfish plodded aimlessly and mindlessly in the water. However, this myth has been firmly dispelled and instead an incredibly sophisticated animal has emerged in its place.

All-Seeing Creature

Box jellyfish are the possessors of 24 eyes giving them a 360-degree field of vision. The fact that the Box Jellyfish has eyes means that it is not a true member of the jellyfish clan, Scyphozoans.

The jellyfish’s eyes are arranged in four sets of six. Each set roughly corresponds to a ‘side’ of the animal’s bell or main body. Each group of eyes are composed of two complex eyes, sometimes referred to as ‘smart eyes’ and four light sensitive pits. Their ‘smart eyes’ each have lenses, retinas and corneas, not unlike our own.

According to new optics research, the jellyfish’s vision is blurred as its eyes are permanently out of focus. Experts have proposed that as the jellyfish lacks a brain, it lacks the ability to focus its eyes.

Jellyfish Warnings

So Why Have Eyes?

The advantageous presence of eyes means that they are able to hunt their prey. This also explains why, unlike other jellyfish, they can travel at speed, 2 knots, a moderate walking pace. Because they possess sight this means that they can avoid obstacles. This is critical to avoiding injury in what is ostensibly a very delicate animal.

Venomous Predators

Box jellies are one of the most venomous of animals. One large species, Chironex flexkeri, sometimes called the Australian Box Jellyfish, is one of the most poisonous animals on the planet. The pain following a stings is instant and has been described as an intense burning sensation.

The Jellyfish’s venom attacks the nervous system, the heart and vital organs. Death can occur within minutes.

Usually those who are more likely to die include those who suffer from pre-existing heart conditions. However, unlike Irukandji, symptoms usually subside within half an hour of being stung. There are regular fatalities each year and some estimate that as many as 10,000 people worldwide are stung each year by some species of stinging jellyfish.

Irukandji Jellyfish

Irukandji, another species of Box Jellyfish, is called after an aboriginal tribe whose folklore recollects of afflictions suffered by bathers. It is a far smaller species of Box Jellyfish. No bigger than a fingernail, it is virtually impossible to spot in the water due to both its size and the fact that it is transparent. Also because of  its small size, Jellyfish nets used ordinarily to protect bathers are ineffective.

Worst Pain Imaginable

Unlike most Jellyfish, whose stinging cells are only found in their tentacles, Irukandji has stinging cells on its main body or bell. Those who have been unfortunate enough to be stung by it, experience intense pain, vomiting, incredibly high blood pressure, and nausea.

Many people who have been stung claim they would have preferred to have died rather than endure the pain such are the levels of agony Irukandji causes. It has been described as a mixture of fire and bone-crushing pressure by victims.

Unlike, other types of Box Jellyfish, Irukandji victims do not experience pain initially, it takes about 30 to 40 minutes for the effects to manifest but sufferers can experience pain for weeks. The vast quantities of noradrenalin that is released is often enough to shut the body down completely. Without medical intervention those stung can die.

What makes Box Jellyfish so hazardous to humans is that we have a very large surface area. Therefore, we end up receiving larger amounts of venom that would normally be administered to the jellyfish’s intended prey.

Why Does Such A Small Animal Need Such Potent Venom?

The reason that Jellyfish appear disproportionately venomous is due both to their delicate bodies and to the fact that they hunt rather large prey.  The 5,000 stinging cells per tentacle helps to ensure that the prey is de-mobilised as quickly as possible.

The toxins that they administer to their prey are so instant-acting that they cause immediate paralyses. This helps to limit any damage that the Jellyfish may receive to its tentacles.

Sting Treatment

If you ever happen to be stung by a Jellyfish, treat the wound with vinegar as this deactivates the stinging cells or nematocysts.

Contrary to popular belief, Ammonia, urine or alcohol do not combat the stinging effect and they may even exacerbate the situation. It is also not recommended to treat the wound with fresh water as this can cause more venom to be released.

Prevention is always the best cure and it is recommended that bathers to not swim in Jellyfish-infested areas during the wet season (from November to April).

Jellyfish Net On Queensland Beach Australian Photo By Colin Henein

Remarkable Sleepers

During a tagging experiment it was discovered that Box Jellyfish “sleep” from 3pm to 6am lying motionless on the ocean floor. Experts believe that this is because of two characteristics. They use their eyes to hunt prey and they have a high metabolism. “Sleep” and a lowered metabolism makes perfect sense if they cannot hunt prey in the dark and doing this helps to conserve energy.

Misunderstood

Box Jellyfish are curious and remarkable creatures which have for so long been misunderstood by us. It is only now that we are beginning to understand just how sophisticated these creatures are. Perhaps given their highly venomous nature we should treat them with more respect and give them a wide berth after all no one wants to experience such levels of pain.

Vital Statistics

  • Box Jellyfish grow to up to 3m (10 ft) in length.
  • They can weigh up to 2kg (4lbs).
  • Box Jellyfish can live for up to one year.
  • They are found in the warm waters of Northern Australia and the Indo-Pacific.


Further Information

For further information on the Box Jellyfish and their behaviours try reading the highly accessible Amazing Jellies: Jewels of the Sea or watching The Art of Nature: Jellies DVD.

You may also wish to check out Yellow Magpie’s post on Comb Jellies.

Amazon.co.uk
For people living in Ireland or the United Kingdom, you can access Amazing Jellies and The Art of Nature: Jellies

Amazon.ca
For those who live in Canada, you can obtain Amazing Jellies and The Art of Nature: Jellies.

Amazon.de
For Germany: Amazing Jellies.

Amazon.fr
For France: Amazing Jellies.


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