Bug-eyed colossus

With satellite imaging, GPS and internet available in even the remotest corners of the globe, it sometimes feels like there is little left to explore in this world. But drop just the length of a football field below the surface of the ocean and you'll be humbled by how little we still know about what's out - or rather down - there.

Take the colossal squid for example. It's one of those deep-sea dwellers bound to give small children nightmares. The alien-looking creature has tentacles equipped with sharp hooks, a massive beak and can grow as long as 10 meters and weigh as much as half a metric ton 500kg (1100lbs) - as far as we know. So few of these creatures have been captured or found (around 10) that much about the way they live - or how big they can actually get - is still unknown.

As one researcher put it aptly at a conference: "Trying to observe one in the ocean is like jumping out of a plane with a parachute somewhere above North America at night, armed with a flashlight, hoping to find a grizzly bear."

Part of the problem is also that the deep sea dwellers don't fare well once they get dragged to the surface and raising young ones in captivity hasn't been successful so far.

Aside from being massive, the biggest colossal squid ever found has set another record: It has the biggest eyes of any known animal. Almost 30 centimeters in diameter, they are bigger than a professional men's basketball.

Why they are so big and why they are much bigger than the eyes of its similarly-sized relative, the giant squid, is yet another mystery waiting to be solved.