Killer jellyfish population explosion warning

Paul Eccleston, The Telegraph 8 Feb 08;

It could easily have been the role model for the terrifying creature in the film 'Alien'.

A perfect toxin-loaded killing machine, there is no creature on earth that can dispatch a human being so easily or so quickly.

The box jellyfish is so packed with venom that the briefest of touches can bring agonising death within 180 seconds.

And if comes under sustained attack it responds by sending its compatriots into a super-breeding frenzy in which millions of replacements are created.

The really bad news is that the box jellyfish and another equally poisonous species, Irukandji, are on the move. Scientists are warning that their populations are exploding and will pose a monumental problem unless they are stopped.

The warning comes in a film Invasion of the Jellyfish to be screened by Channel 5 on Tues February 12.

It focuses on the change in behaviour patterns of jellyfish in the Pacific Ocean off Japan and Australia due to depleted food resources as humans fish the world seas.

But a similar incident happened much closer to home in November 27 off the Northern Ireland coast when a 10 mile wide, 13 metre deep swarm of jellyfish swam attacked the country's only salmon farm, wiping out over £1million worth of stock.

Billions of small jellyfish, known as Mauve Stingers, flooded into the cages about a mile into the Irish Sea, off Glenarm Bay and Cushendun.

On the other side of the world scientists who managed to place tracking devices on the jellyfish in the Pacific proved that they were not drifting on the ocean currents but heading determinedly - and at the speed of an Olympic swimmer - towards the coast.

In the film perplexed Japanese salmon fishermen are seen hauling in tonnes of box jellyfish in their nets. The few fish they do haul in are writhing in their death agonies after being stung.

An attempt by the Japanese government to protect their fish stocks by wiping out the swarms using a fleet of commandeered fishing boats to drag razor-sharp wire through them backfired spectacularly.

Scientists discovered captured big female box jellyfish were swollen with millions of eggs - far more than they would normally carry. Similarly males were carrying billions of sperm. Trying to kill them had unleashed a breeding explosion because they are genetically programmed to ensure their survival by producing more offspring than normal when under attack.

The jellyfish have a formidable array of genetic equipment to help them survive:
# Four brains that operate competitively in the search for food.

# A highly complex sensory capacity and the ability to distinguish colour.

# The ability to live in inhospitable waters at a depth of up to 10,900 metres.

# A total of 24 eyes with moveable pupils giving them 360-degree visibility.

# Box jellyfish have 6-8ft long tentacles. Just 5-6ft across the body is enough to kill a human in 180 seconds.

# Venom is released on contact - even after it is dead - and each creature has 4000,000,000 venomous fibres.

# Humans who have been stung and survived have needed 30-40 milligrams of morphine. A broken leg requires between 5-10 milligrams.

# Despite decades of study scientists have been unable to unravel the mysteries of its complex venom but it is known to contain 20 different proteins.

The swarms of jellyfish are multiplying in the Western extent of the Pacific ocean and threatening 20,000 miles of coastline off Japan, Irian Jaya, Papua New Guinea and Australia.

In the film scientists conclude that they swim towards land because it is easier to kill their main prey - fish - in shallow water off the coast which puts them on a dangerous and potentially fatal collision course with unwary swimmers.

In an experiment off the north Australia coast small netted pools were created and kept the large box jellyfish out but people were still being stung. They eventually discovered the tiny transparent Irukandji - almost invisible in daylight - was slipping through the holes in the nets.

The only deterrent so far found is a colour - red. The jellyfish simply ploughed through white-coloured poles in the water and swam round black poles but they stayed as far away as they could from red poles.