Emerging through the gloom they advance like an army across the floor of the ocean - all 250,000 of them.
These are giant spider crabs who spend most of their lives in deep water but once a year, off the coast of southern Australia, they edge along the shallows to moult and to mate.
Having shed their old shells, they are soft-bodied for a while before their new shell hardens. This is their opportunity to procreate but it is also a time when they are vulnerable to attack from stingrays.
Life is the latest wildlife epic from the BBC?s award-winning Natural History Unit. It has the revelation, cinematic style, sense of place and emotionally involving individual sequences that that were the hallmark of The Blue Planet and Planet Earth, with all the scope, detail and content of an Attenborough epic, and the addition of close-up, intensely dramatic new behaviour ? all captured by the world?s top wildlife photographers with the aid of the most cutting-edge and sophisticated filming techniques
We should be happy not because of what we have, but what we are.