One Ocean takes us on a journey from the intense heat of the tropics to our planet's frozen poles. Life has spread to almost every part of the oceans, but there are many different worlds here, and each presents unique challenges.
In the tropics, a baby Dolphin learns how to rub against a particular coral which may have medicinal properties. A Tuskfish uses an anvil to open Clams. And Giant Trevally fish leap clear out of the water to snatch birds on the wing.
In temperate seas, Mobula Rays create an enchanting display at night, as tiny organisms light up when disturbed by their wingbeats. Two separate species - False Killer Whales and Bottlenose Dolphins, gather together to make a formidable army. And a female Kobudai Wrasse changes sex to challenge an older male for his harem.
But our ocean system is changing. In the Polar north, the summer sea ice has retreated by 40% in the last 30 years, with profound consequences for its wildlife, including a Walrus mother and pup. Ocean currents help maintain a climate favourable for life... But for how much longer?
Key story - Giant Trevally
Written by Miles Barton, Sequence Director
Giant Trevally are a big, 40kg bulldog-like fish, solid and aggressive. A rumour had come to us in Bristol from some South African fishermen that they’d seen Giant Trevally jumping out of the water and catching sea birds in mid-air. There wasn’t a single picture or video clip of this happening. I haven't been out on a shoot in 20 years where I haven’t had at least a still picture of the behaviour to go on. So I was sceptical, to say the least.
But our researcher Sophie [Morgan] talked to these fishermen, and they convinced us, so we decided to do the shoot. Four of us went all the way to the Seychelles, including an underwater cameraman, a topside cameraman and a Cineflex gyro-stabilised camera to go on the boat. You only take on one or two of these types of risky shoots on a show. This was our biggest gamble.
We arrived and got very excited because yes, there were splashes everywhere: the fish were leaping out of the water and they did seem to be grabbing birds. But it happened randomly and very fast so we didn’t know how we were ever going to get a camera on the action!
We started out using the stabilised camera fixed to the boat. Our local boatman Peter King, was able to predict an area where the fish would attack but it was still very difficult to frame up on.
After a week of intense frustration with just a few shots filmed Peter suggested we go to the beach and where at certain stages of the tide, the Giant Trevallies came close to the beach. The beauty of this high point was that you could see the fish stalking below. Peter would tell us to ignore one, and aim for another one. Somehow he knew which one was hunting, too.
So we ended up going from a very high tech approach, to the simple use of a camera on a tripod with the best local advice and we got it - they’re amazing shots! The Giant Trevallies leap out of the water and they really do take the bird out of the sky. A genuine bird-eating fish.
We will be showing the footage to bird researchers on the island so they can study the behaviour in detail for the first time, as it has never been filmed before.
1. Indo-Pacific Bottlenose Dolphin (pictured below) - South Africa, East Cape
2. Bottlenose Dolphin - Egypt 3. Orange-dotted Tuskfish - Great Barrier Reef, Australia 4. Giant Trevally, Sooty Tern, Lesser Noddy Tern - Indian Ocean 5. Mobula Rays - Sea of Cortez, Mexico 6. False Killer whales, Bottlenose Dolphin - New Zealand 7. Kobudai - Asian Sheepshead Wrasse - Japan 8. Killer Whale, Humpback Whale - Vengsoya & Andfjord, Norway 9. Atlantic Walrus (pictured below), Polar bear - Svalbard
Location: Lizard Island, Australia Species: Orange-dotted Tuskfish
Using a rock as an anvil to break open clams is an example of tool use in fish
The Tuskfish filmed would repeatedly swim back to the same coral and use the hard growth to crack open bivalves
This behaviour has been filmed professionally for the first time for Blue Planet II
The Tuskfish almost always uses the same anvil as a tool, which is perfectly suited to the job
The bowl shape of the Tuskfish’s anvil helps the shells not fly too far when it loses hold of them after a vigorous strike
The Tuskfish filmed could hit some tough shells well over fifty times to get them open
The Tuskfish’s snaggly teeth protruding from its mouth to help it grip the shells
Giant Trevally and Terns
Location: Indian Ocean Species: Giant Trevally, Sooty Tern and Noddy Tern
Over 500,000 Terns gather on the atoll every year
Giant Trevally are formidable hunters and top predators in the ecosystem. They’re able to utilise an array of senses to home in on their prey - including sight, sound and even sensing pressure changes in the water using their lateral lines
Giant Trevally can switch between schooling hunters and individual hunters: One study in Hawaii showed higher predatory success when juvenile Giant Trevally schooled to catch schooled herring. On the flip side, they found that lone juvenile Giant Trevallys had higher feeding success rate when targeting lone (non-schooling) Herring. So, schooling isn’t always beneficial even for the same prey species!
This sequence was filmed in detail for Blue Planet II for the first time, and is a new example of a little-known behavioural interaction between species
Mobula Rays and bioluminescence
Location: Sea of Cortez Species: Mobula Rays
Using the latest in low light filming technology, the team were able to film this event underwater for the first time
Mobula Rays are thought to jump in order to communicate with other members of their species. It could be to indicate the discovery of a good feeding area, or to bring more mobulas into a mating event, but no-one knows for sure!
Bioluminescence is used by many marine organisms as a means of frightening potential predators, attracting mates, or enticing prey
Location: Pacific Ocean, Japan Species: Asian Sheepshead Wrasse
When female Kobudai reach a certain age and body size, they can undergo a transformation, changing from a female to a male
This sex change has selective benefits as by mating with a wide variety of females, males will pass on more genes than an individual female would
Male Kobudai can be very large - weighing 15 kilograms and being a metre in length
This is the only known non-antagonistic interaction between Orca and Humpbacks in the world
Around 1,000 Orca have now been identified in the area of northern Norway
This is a new event, first documented in 2011
The North Atlantic holds around 20 billion Herring
Humpback Whales can weigh between 25-40 tonnes and reach 18 metres in length
A three to four metre Humpback calf can nurse for up to a year - growing four and a half metres per month. That amount of growth requires a lot of milk - up to 200 litres a day
Tuskfish using tools
The team spent over 100 hours in the water with this little fish and got to know his daily commute
Lizard Island, Australia
The Great Barrier Reef contains so many species that it’s a ferociously competitive environment. Animals do what they have to in order to get ahead. We’d been looking for stories that illustrated this point and our researcher Yoland Bosiger had read a paper that described Tuskfish getting ahead of the competition by using tools!
However, we didn’t know how many fish were capable of this extraordinary behaviour and where or how we could film it. Yoland contacted Dr Alexander Vail who lives on Lizard Island on the Great Barrier Reef and asked him to seek out these Tuskfish and see if the behaviour was occurring there. Sure enough, after many dives he eventually found some Tuskfish using anvils to crack open shells. There was one fish in particular that kept going back to a certain boulder coral.
He picks up the clam in his mouth and swims it back to this coral and starts whacking it. This coral actually acts as an anvil for him and he’s using it as a tool to break open the clams to get to the inside. He would hit it on one specific spot on the reef each time.
Over the next month the team spent over 100 hours in the water with this little fish and got to know his daily commute. We became quite fond of him and named him Percy. Sometimes he’d blow in to the sand to find a clam, sometimes he’d steal them off other fish. But he’d always swim them directly back to what we called his ‘castle’.
The behaviour seemed fairly obvious to us once we got our eye in and yet tool use has rarely been seen on the Great Barrier Reef before filming for Blue Planet II. There has been only one scientifically documented observation of the behaviour in 2011 and even Dr Alexander Vail who spends a lot of time at Lizard Island had not seen it. On a coral reef, with so many species of fish all going about their daily business it’s maybe not so surprising that even the most charismatic behaviours can go unnoticed. It makes me wonder what might be out there left to discover.
Rachel Butler Assistant Producer, One Ocean
False Killer whales and Bottlenose Dolphins
New Zealand waters
False Killer whales or Pseudorca are actually dolphins. They’re black, up to 6 metres long and they look like Pilot whales, so they’ve always been called whales. While we were in development a scientist in New Zealand called Jochen Zaeschmar, who has been studying them for 15 years, published a paper about the interaction between the False Killer whale and the oceanic Bottle Nose Dolphin. The False Killer whales visit New Zealand for only a few months year, and when they do he always sees them with the Bottlenose Dolphins. During his observations he noticed that they were interacting on hunts in a way that didn’t appear to be coincidental. It was almost as if they were working together and they even appeared to have best friends within the group. The same individuals were being seen with each other for the duration of their time off New Zealand, year after year, since they were calves. We wanted to see what was happening. John [Ruthven - Producer] worked on the original Blue Planet and he always encouraged us to try and film things that had never been filmed before. But obviously that’s the hardest challenge.
It seemed as if these two species were communicating with each other somehow and John was really excited by the idea. It sounded so fantastical. We thought, ‘That can’t be true, can it?’ And more importantly, ‘Can we get anything that would show that?’
The main problem, of course, was finding them. The open ocean is just massive, and you have to be in the right place at the right time. I went out to join a New Zealand cameraman Steve Hathaway and seasoned cameraman Tom Fitz at the time of year the False Killer whales historically have been seen. We were searching an area the size of Belgium for something the size, at best, of a football pitch. You’re faced with decisions like, ‘Now we’ve got the full crew here, we’re out at sea, helicopters on stand by but… the dolphins have… gone, not even a whale watching boat is seeing them, anywhere of North Island. So we either go back home and we get nothing, or, we put another spotter plane up tomorrow and contact every whale watching or sport fishing boat we can.’ That’s what happened and after serious perseverance I think it was the right call.
Eventually we got the unique aerial shots we were after, we could see several hundred bottle nose dolphins (at times close to 1,000) around the outside of 150 false killer whales in the middle. We filmed the two groups of what are in fact both dolphins, coming together. We could see social bonding and then a mass hunting-party where as they hunt in slightly different ways, and that increases their chance of finding prey. This was the first time Jochen had seen their formations from the air and their full numbers in one go, as being up high gives a full view of the all the animals compared to a limited view from a boat. This also allowed Jochen for the first time off New Zealand to get a full count and make ID references for all the False Killer whales so he can monitor how these rare animals are doing year after year to see if their numbers change.
As well as the aerial filming we had Steve and Tom, our underwater cameraman to get the feeding action when they stopped moving long enough and a tow-cam behind a boat to capture them hunting from underwater because they go phenomenally fast - when you see the footage it feels like you’re out there swimming with them, this was also the first fully successful use of the new ultra-high definition towcam on Blue Planet II.
What’s most amazing is that in other parts of the world False Killer whales will harass or even eat dolphin. Off New Zealand there’s a truce, and with a level of friendship and cooperation Jochen is still learning more about every time he encounters them.