Wellington (AFP) - Scientists said Tuesday a female colossal squid weighing an estimated 350 kilograms (770 lbs) and thought to be only the second intact specimen ever found was carrying eggs when discovered in the Antarctic.

The squid had been kept in optimum freezing conditions at the Te Papa museum in Wellington ever since it was brought back to New Zealand from the seas off the frozen continent during the southern hemisphere's summer.

The colossal squid is thought to extend up to 4-5 metres (13-16 feet) from tip to tentacle and weigh up to 500 kilograms. Its relation, the giant squid, can grow a lot longer but is much more spindly.

This specimen, like other octopus and squid species, has three hearts -- one to pump blood around the body and two for its gills (lungs) -- and is estimated to be about 3.5 metres in length.

"This one had two perfect eyes," scientist Kat Bolstad from Auckland University of Technology who led the examination told AFP.

"They have very large and very delicate eyes because they live in the deep sea. It's very rare to see an eye in good condition at all."

Measurements revealed the animal's eye was 35 centimetres (14 inches) in diameter, and confirmed that the specimen was a female.

"We were excited to find that out... as it turns out this one is a female, and it has got some eggs," Bolstad told reporters.

"This was by far the most perfect colossal squid that I have seen."

The only other time scientists anywhere have had the chance to examine an intact colossal squid was in 2008, also at Te Papa, the museum said. That specimen was also female.

Bolstad said the latest specimen was so well preserved the scientists were able to examine it with an unusual level of detail, including the lens on the eyes.

"The fact that we have a specimen in good shape, but that we can get so much information from and still have in good shape, is a win-win," Bolstad said

The squid was found by a fishing vessel in Antarctica last southern hemisphere summer when the boat's captain, recognising what had come to the surface, carefully netted it and brought it onboard.

The number of colossal squid in the ocean is unknown but Bolstad said sperm whales in the Antarctic ate a lot of the animals.

After samples were taken from the squid examined on Tuesday, it would be preserved for further research and display, she added.