That means they take up more space on the planet than us.

The reason has been put down to overfishing of other species and climate change.

A report in the Australian science journal, Australasian Science, said marine researchers are now in universal agreement that cephalopods have been given an advantage not available to any other sea creature.

And as a result they have been allowed to flourish.

Their growth rates also seem to be increasing as is their body size.

The findings may offer an answer to the mysterious appearance of a giant squid on the coast of Tasmania last week and hundreds of squid washed ashore on the coast of California this week, although El Nino is also being partly blamed.

Squid are now regarded as the "major player'' in the world oceans by sheer volume alone.

Overfishing of some fish species has taken away competition for the squid in finding food resources.

The warming of waters due to climate change have also allowed squid to expand their populations.

Dr George Jackson from the Institute of Antarctic and Southern Ocean studies in Tasmania said squid thrived during environmental disasters such as global warming.

The animal ate anything in that came their way, bred whenever possible and kept growing.

"This trend has been suggested to be due both to the removal of cephalopod predators such as toothed whales and tuna and an increase of cephalopods due to removal of finfish competitors,'' said Dr Jackson.

"The fascinating thing about squid is that they're short-lived.

"I haven't found any tropical squid in Australia older than

200 days.

"Many of the species have exponential growth, particularly during the juvenile stage so if you increase the water temperature by even a degree it has a tremendous snowballing effect of rapidly increasing their growth rate and their ultimate body size.

"They get much bigger and they can mature earlier and it just accelerates everything.''

The Food and Agricultural Organisation of the UN supports the theory claiming squid landings have been increasing over the past 25 years at greater rates than fish.