The lady spa turtle in Blue Planet II is our new spirit animal ?

And you know what isn't? The Bobbit worm

If you had any illusion that filming Blue Planet II wasn't a massive, exhausting, money and time-burning exercise you only had to watch the last fifteen minutes of Sunday night's episode, 'Coral Reefs.'

A BBC crew had schlepped all the way to a remote atoll in French Polynesia to catch the once-a-year, full moon mating ritual of thousands of grouper fish, bringing with them a fish-mating expert and equipment that could pay the salaries of seven Eastenders cast members.

For days they waited carefully for the groupers to do their thing... only to jump in one morning and find they'd missed the whole spectacle. The only solution? To come back and do it all again next year.

But who cares when it's this good? Horror movie worms, grouper-shark pile-ons and dolphins playing catch? Shut up and take our money, BBC!

Coral Reefs was a bittersweet third episode that showed us just how extraordinary the colourful underwater habitats we seem intent on annihilating really are. We opened with a cuttlefish that's mastered the art of hypnotising crabs and closed with a bone-chillingly huge number of reef sharks.

It's hard to pick a highlight (every clip is a masterpiece) but special mention to the lady sea turtle in the first half of the programme who we watched up-and-about in the early hours of the morning in the coral reefs of Borneo.

What was her reason for the early rise? Was she out looking for food? Or maybe a nice spot to catch a guy-turtle for some business time?

Neither actually - she was off for a treatment. On a nearby rock where, as Attenborough pointed out, 'decades of visiting turtles have worn a hollow in the top', was a special patch where the lady turtle could take a load off as teams of tiny blennies and surgeonfish picked off algae, parasites and dead skin from her body and shell.

New research suggests the turtles find this process a great stress-buster as well as a practical way to keep themselves parasite-free, and as she closed her eyes in bliss we could well believe it. Though her peace was quickly shattered by two male turtles who muscled in on her patch for their own treatments. She had a booking, guys.

Less relaxing was our introduction to something called a Bobbit worm, a creature better suited to last week's episode, 'The Deep'.

The Bobbit waits until dark to snatch little fish from its underground hiding place in the sand, gulping them down as sand appears to rise eerily like smoke from its hole. Horrifyingly, the Bobbit is a metre long.

But then, when the sun comes up the bream that the Bobbit hunts at night appear to get their own back on the worm by indignantly blowing sand away from its hiding place.

Light and shade - what this show does best.

Roll on next Sunday...