Blue Planet II – ‘Coral Reefs’

As you might have guessed, this episode was about coral reefs, such as the Great Barrier Reef in Australia and the Coral Triangle in South East Asia. David Attenborough’s narration pointed out that “coral reefs cover less than a tenth of 1% of the ocean floor, but are a home to a quarter of all known marine species.” The coral reefs can grow for a long time, hundreds sometimes millions of years.

They used the metaphor of cities, describing coral reefs as “undersea cities”,”a metropolis”. A large, varied population, full of bright and interesting sights, an area that never sleeps and there’s always something going on. A similar metaphor of cities was used to describe jungles in Planet Earth II, so you could also say that coral reefs are the jungles of the sea.

Sheltered areas of the reef were compared to suburbs. Away from the crowds of the city, they are much more peaceful and there is more space. The problem is that there is nowhere to hide.

An early sight in the episode were glimpses of a clownfish and a blue tang fish, sure to remind people of Finding Nemo/Finding Dory. Clownfish make a bigger appearance later on in ‘Coral Reefs’. They live in anemone, as they are immune from its poison. That poison is extremely deadly to other species, which makes the anemone an ideal place for clownfish to live in as they and their young are protected.

Clownfish families are run by a matriarch, a big female. The smaller male tries to find something for the female to lay her eggs in. He finds a shell, but it’s too heavy, and it already has a hermit crab living in there. He then tries an old plastic bottle, but it’s too light, and floats away. A coconut shell he finds is “just right”. It’s still a bit heavy for him to move all the way, but the female helps him. Clownfish, like kobudai, sometimes change sex too, but with clownfish it is males becoming females.

Cuttlefish prey on crabs, and have a trick where they change colour to a shimmering white, which seems to hypnotise the crab. But they aren’t always on top of the food chain, the hunter can become the hunted after all, as cuttlefish are preyed on by sharks. We see a cuttlefish hunting a crab. Then a shark passes, so the cuttlefish hides away. When the shark has gone, the cuttlefish finds a different crab, and catches and eats it. I suppose this shows just how much of survival is down to luck and random chance as much as anything else.

A grouper looks for fish among corals, but it is much too big to fit into the cracks its prey hides in. Octopus can reach into the narrow cracks with their tentacles, but finding the prey can be tricky. The two creatures combine their skills and work together! The grouper changes white to signal where the prey is hiding, the octopus reaches in, and the fish leave the rocks. Sometimes the octopus will get the meal, sometimes the grouper, but the point is they work together, and are seen swimming alongside each other!

Green turtles go for a sort of spa treatment! Fish like blennies and surgeonfish clean off all the algae, parasites and dead skin off the turtle. The fish get food, the turtle gets cleaned. This “spa treatment” can be a hard-to-get luxury though, as competition for it can lead to physical fights. We see a small female forced out of her spot by two big males. However, the two males then fight each other, so she sneaks back in!

The Red Sea is in a desert in the Middle East, and in contrast to the desert on land, the sea is full of life. We see dolphins appearing to play a game with the coral. They just picking them up, then drop them down. Dolphins evolved from a dog-like land creature, so I wonder if its similar to how dogs like to play fetch?

Sailors in past times thought many natural marine phenomenon were caused by sea monsters. Whirlpools were thought to be this, in Greek Mythology for example a sea
monster called Charybdis, basically a large tooth filled monster mouth at the bottom of the sea, was thought to cause a whirlpool.

I did think at times in this episode the sea resembled a sky, some grey reef sharks looked like fighter aeroplanes, the tide looked like a snowstorm and the whirlpool looked like a cyclone. Speaking of cyclones, there is the rather graceful Manta Ray cyclone, where they swim together in circles, as a way of filtering out the plankton.

There are real animals that look like sea monsters, such as the bobbit worm, it’s a metre long with sharp pincers, it is a very creepy looking creature. As a species, they have been around for a while too, their ancestry stretches back 400 million years! At nightfall, it comes out from underneath the sand to catch its prey.  The first victim we see is a lionfish, a pretty fish with fancy fan-like fins. During the day, the bobbit worm can be seen. Bream fish get together and blow sand away covering the worm, taking away its “element of surprise” mode of attack. It is still dangerous though, as one bream discovers far too late as it gets too close and is eaten by the worm.

Groupers make another appearance later in the programme. The grouper fish lie on the seabed, waiting for the exact right time, when the tide turns. At that point, they all swim up, the females go first, releasing their eggs, then the males follow, releasing their sperm, which fertilises the eggs. The adult grouper fish are what the grey reef sharks are waiting for, and they swim down and eat them. The fertilised eggs though are swept away to safety by the tide. That said, most of those fertilised eggs will never hatch, they will be eaten by other creatures, and not all of the ones who hatch will make it to adulthood. But there are billions of them, so even though only a few survive, it is still enough.

The coral reefs and the fish seen in this episode were very bright and colourful, often unexpected colours like neon green and purple. Parts of this episode were fun, but it ended on a sad note, and once again it’s because of us humans.

Global warming is having a dreadful effect on coral reefs. The rise in temperature causes the coral to eject their plant-like cells. This makes them lose their colour, and that means they lose their main source of food, so they die. With the coral dead, that leaves the creatures which inhabit coral reefs homeless.

The coral become bleached white. Seeing their colour gone and them looking like a white, dead forest is heartbreaking really. Some scientists think that by the end of this century coral reefs will no longer exist. The only thing coral reefs have in their favour to escape this fate is the fact that they are able to reproduce quite well. At a full moon no less, they can spawn, which will be swept away by the ocean to possibly create a brand new coral reef miles away. But it’s looking bleak at the moment, sadly. I mentioned Greek myths before, and it reminded me of Pandora’s Box. The horror is out there and the damage is done, leaving only hope. Though we can do something about it in this case, as we know the cause is global warming.

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