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Oceans

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“ Deep beneath the water’s surface, the world’s largest predator — the Mosasaurus — lies in wait to ambush unsuspecting prey. ”

― The official Apple TV+ episode synopsis for Oceans

Oceans is the fourth episode of the second season of Prehistoric Planet, and the ninth episode of the series overall.

Segment I: Phosphorosaurus[]

“ The ocean. The largest habitat on the Prehistoric Planet, and home to one of the biggest predators that has ever lived, a giant mosasaur. But not all mosasaurs are ferocious, 50 foot-long monsters... ”

― David Attenborough, Oceans

The first segment of the episode, taking place somewhere in Hokkaido, Japan,[PhP 1] starts with a massive Mosasaurus swimming close to a reef, prompting several of the area's inhabitants to scamper and hide. Even so, the point of the segment was to prove that not all mosasaurs are alike.

“ Taking refuge in the reef is Phosphorosaurus. She too is a mosasaur, one of the smallest, at less than ten feet long. ”

― David Attenborough, Oceans

In the maze of rocks and corals, a female Phosphorosaurus makes her way through as her bigger relative patrols the waters just outside her hideout, cautiously avoiding danger as she occassionally rises to the surface to breathe.

“ She spends the daylight hours hiding from danger. But once or twice an hour, she has to dart to the surface to grab a breath. Like all of her kind, she is air-breathing. She's dwarfed by the biggest mosasaurs. But she too is a deadly predator. And she doesn't always hide in the shadows. When the time is right, she becomes a hunter. And that time is when the sun sets. ”

― David Attenborough, Oceans

As night falls, Phosphorosaurus emerges from her sanctuary, seeking a particular type of food. With her eyes dilated greatly like an owl's, she sets out to meet her targets. In almost-total darkness, a massive shoals of lanternfish migrate, flashing their lights to confuse and disorient any predators that want to feast on them. But with her large eyes, Phosphorosaurus can visualize the dazzling display before her very well, charging several times through the shoals of fish to grab as many as she can.

“ Their faint, eerie light is produced by a chemical reaction inside their bodies. A flash of this bioluminescence can be used to confuse predators. And when seen from below, the glow enables them to blend with - and hide against - the ocean's moonlit surface. But they can't hide from Phosphorosaurus. For her size, her eyes are the largest of any mosasaur, allowing her to see through the illusion and pick out her prey. ”

― David Attenborough, Oceans

By dawn, as the lanternfish shoals descend back to the depths and the massive mosasaurs come out, once again prowling the reef, Phosphorosaurus returns to hiding in her sanctuary amongst the coral-encrusted rocks, waiting for nightfall to hunt once more.

Segment II: Hesperornis and Xiphactinus[]

“ By day, the prehistoric ocean provides opportunities for a very different type of hunter. In the warm, shallow seas of North America, fish numbers can almost match the nocturnal lantern fish shoal. And they are a magnet for 6 foot-long Hesperornis. ”

― David Attenborough, Oceans

The second segment of the episode, by the warm, shallow seas of North America, a massive shoal of fish attracts many Hesperornis, with the flightless seabirds catching several fish with their beaks full of needle-sharp teeth.

“ Xiphactinus, known as 'X-fish'. A feeding opportunity soon attracts them in large numbers. At over 17 feet long, they are one of the largest and fastest fish in the ocean. With its huge mouth, Xiphactinus can scoop up several fish at once, and has even been known to swallow prey half its size whole. At first, there is plenty for everyone. But as fish numbers dwindle, the X-fish turn their attention elsewhere. Predator is about to become prey. ”

― David Attenborough, Oceans

The presence of the shoal soon attracts even larger predators. Several Xiphactinus arrive to take their share. But as the shoals of fish diminish, the X-fish, still hungry, seek out even larger prey to satiate their appetites.

“ The Hesperornis have only one option; to swim for their lives. Xiphactinus is faster; Hesperornis is more agile. ”

― David Attenborough, Oceans

Suddenly, several Hesperornis are attacked by Xiphactinus, with some even being swallowed whole. The surviving Hesperornis frantically attempt to escape the predators with evasive maneuvers. While Xiphactinus is faster, Hesperornis is more agile, allowing some of the birds to repeatedly dodge their pursuers just a second before getting grabbed and devoured.

“ But in the eyes of an X-fish, anything is on the menu... even their own kind. Within minutes, the banquet is all but gone, and the predators move on. ”

― David Attenborough, Oceans

Following this, one Xiphactinus is shown chewing on the body of a smaller X-fish, for their voracious appetites meant that any other living thing is nothing more but potential prey. With the shoal of fish reduced to nothing, the hunters leave the area.

Segment III: Baby Ammonites[]

TBA

Segment IV: Tuarangisaurus and Mosasaurus[]

“ ... the very heart of the Pacific Ocean. These enormous atolls and the lagoons at their center provide the only shelter for thousands of miles. In this rare place, Tuarangisaurus, a kind of elasmosaur, finds safety. ”

― David Attenborough, Oceans

The fourth segment of Oceans takes place in the Darwin Rise, a continent-sized region in the very heart of the Pacific Ocean, known for many atolls that have formed due to millions of years of geological activity throughout the Cretaceous Period. Some of the seamounts can cover about 1,200 square kilometers (463 square miles), roughly matching the size of the city of Los Angeles in California, USA, with steep, earthquake-formed flanks redirecting currents and drawing in animals of all sizes to the oasis within, the lagoons within atolls like these serving as the only sanctuary for thousands of miles.[DN 1] In one seamount of such size, several Tuarangisaurus take refuge.

“ But outside these shallows is a different story. Each day, the elasmosaurs must venture into deeper water. Canyons in the atoll walls lead from the atolls to fresh feeding grounds. This deep water attracts not just the hungry elasmosaurs, but the predators that hunt them. The biggest in the ocean. Fifty foot-long Mosasaurus. ”

― David Attenborough, Oceans

However, every day, the elasmosaurs need to hunt, and to do so, they must leave their shallow shelter and venture into the deeper waters of the open ocean. There, where nutrients rise from the ocean floor, thousands of fish gather, ensuring a plentiful supply of food for the elasmosaurs. In turn, however, they themselves become part of the menu of the rich feeding grounds. A 50-foot (15-meter) Mosasaurus, the biggest predator in the Late Cretaceous oceans.

Mosasaurus accelerates upwards with the C-start technique
Mosasaurus accelerates upwards with the C-start technique
“ Streamlined bodies and four powerful flippers give elasmosaurs great maneuverability. But their daily feeding forays make their movements predictable for an intelligent and patient hunter. Mosasaurus is an ambush predator. This enormous animal uses its huge tail to accelerate with astonishing speed. ”

― David Attenborough, Oceans

As the elasmosaurs continue to feed, the Mosasaurus stalks them from the ocean floor, having predicted their movements due to their daily feeding forays. In one sudden movement, the mosasaur rushes upward and almost catches an elasmosaur, which manages to escape along with the rest of its pod. Unlucky in catching prey, the Mosasaurus retreats back to the ocean floor.

“ This time, unlucky. In fact, most hunts fail. But with so many elasmosaurs living here, it’s not long before there is another opportunity. Camouflaged against the dark canyon floor, the Mosasaur can approach unseen, waiting for a young, inexperienced individual, the ideal victim. ”

― David Attenborough, Oceans

With many elasmosaurs around, it didn't take long before another opportunity presented itself. Camouflaged against the ocean floor, the Mosasaurus awaits for an easy target, and rushes at it from below, emerging out of the water with the elasmosaur in its massive jaws.

“ Mosasaurus can strike their prey with such force that the impact alone can kill. It's an attack so swift, the elasmosaur almost certainly never saw it coming. ”

― David Attenborough, Oceans

The Mosasaurus circles around the Tuarangisaurus, which was instantly killed by its assault, floating just beneath the surface of the water. With the hunt over, the mosasaur grabs its prey and drags it to the bottom for it to feed on.

Segment V: World of Ammonites[]

“ They are one of the most successful groups of animals to have ever lived, flourishing in the warm, temperate seas, and even the coldest waters at the poles... ”

― David Attenborough, Oceans


Of the ammonites that escaped the rock pools, less than 1 in 100 have survived several months at sea. These have found a sea grass bed off the coast of Europe, where shoals of ammonites appear in a variety of sizes and shapes. Ammonites found here include the six foot long Baculites, which feeds near the sea floor, and the similarly-sized Diplomoceras, which is shaped like a paper clip. They eat plankton, crustaceans, and some even eat fish; all of which are found in abundance here. Adult nostoceras favor the sea floor in deeper water.

Ammonites have been thriving in these prehistoric oceans for almost 400 million years and there are thousands of species- one of the most successful species to have ever lived.

Segment VI: Morturneria[]

The sixth and final segment of Oceans takes place in the frozen seas surrounding Antarctica.

“ ... like here in the frozen sea around the Antarctic. After a winter of near-total darkness, the low sun is beginning to melt the ice, making it accessible once more for a giant seasonal visitor. ”

― David Attenborough, Oceans

After a long, cold winter of almost-total darkness, the low sun shines down for the first time in months, melting and opening up some gaps in the ice.

“ Morturneria, a strange type of elasmosaur. They are warm-blooded, with a thick layer of blubber which conserves the heat in their body. They're one of the world's most secretive and elusive animals. This pod has migrated nearly two thousand miles from South America to arrive here in time for spring. ”

― David Attenborough, Oceans

Emerging from one of these gaps is a Morturneria followed by its calf, which snuggles up to its parent. These Morturneria are part of a pod that traveled 2000 miles from South America to feast in the Antarctic during spring. Within another ice gap, a small group of four Morturneria, are shown resting up for the moment.

“ It's the first time this year's calves will have encountered sea ice. It can be dangerous for an air-breathing reptile. They can only grab a breath of air where there are gaps in the ice. Adults must navigate carefully to find them, and the youngsters must stay close. ”

― David Attenborough, Oceans

One calf dives down under the ice to emerge out of another ice gap just a short distance nearby, where four adult Morturneria are waiting.

“ These cold waters are an excellent habitat for this giant's favorite food. Polar mud, full of small creatures. There can be hundreds of tiny animals in every square foot of seafloor. Separating what's edible from the sticky mud is a challenge. But they have a neat solution. Scooping up a mouthful, they partially close their jaws, creating a giant sieve to filter out the food. These are the only animals to have evolved teeth to feed in this way. ”

― David Attenborough, Oceans

Deciding it is now time to feed, the pod of elasmosaurs descend to the depths, scraping their half-closed jaws against the the sea floor (with some sweeping their mouths horizontally across the seabed, and others rushing forward to shovel in a mouthful of it), scooping up the mud and filtering out the hundreds of tiny animals with their sieve-like combs of needle-like teeth. A Morturneria calf returns to the surface to briefly take a breath of air, then dives back down to rub against its mother before surfacing with her to breach the surface.

“ The Morturneria will feed here all summer until the water ices over again in the polar winter. In warmer waters, they will face other challenges, but the most resourceful animals will always find opportunities in the vast oceans of the Prehistoric Planet. ”

― David Attenborough, Oceans

The segment ends with the calf swimming around in the ice gap under the watch of its mother as the view zooms out to show the extent of the frozen seas of Antarctica under the light of the low sun.

Uncovered Segment I: How Fast Was A Mosasaur?[]

This Uncovered segment is dedicated to discussing how fast a mosasaur could be.

“ Mosasaurs were seagoing lizards. Think of a giant, swimming, whale-sized Komodo Dragon. Tapered snout, rough skin, four fins instead of normal limbs, and a long tail that would look a lot like a shark tail, but upside down. That's basically a mosasaur. ”

― Dr. Michael Habib, University of California

Presented as the main focus is the largest mosasaur, Mosasaurus hoffmannii. The secret to the success of this ambush hunter is that it can move with incredible speed while it was only stationary moments before. Today, this is demonstrated by crocodiles, which have muscles that can deliver short bursts of tremendous power. Dr. Michael Habib, one of the show's consultants, brings up how mosasaurs may have bent themselves in a C-shape, then, in one sudden movement, push off of the water on the side of their bodies. As seen in modern-day fish, this "C-start" technique allows them to accelerate from a standstill to full speed in an instant. The suggestion is that mosasaurs use this same technique on a much greater scale. Using a 42-foot, 12-ton mosasaur for reference, the Prehistoric Planet research team ran a unique test four times to finally figure out exactly how fast can Mosasaurus hoffmannii actually swim.

“ This mosasaur could probably clear 75% of its body length in one single second. That means if that mosasaur is 17 meters away from you, in one second, it will be 75% closer, and in the 2nd second, it would have surpassed you and probably eaten you along the way. ”

― Kiersten Formoso, University of Southern California

The force generated by a mosasaur traveling at full speed is compared to the impact of a full-sized semi-truck, which, along with the mosasaur's powerful bite force, can prove immediately fatal.

“ Mosasaurs could reach 30 miles an hour in as little as one second. This is what makes them arguably the ultimate marine predator of all time. ”

― David Attenborough, How Fast Was A Mosasaur?

With this, based off of these calculations, a mosasaur 13 meters (42 feet) in length like the one in the diagram displayed in this segment could travel 9.75 meters (32 feet) per second, and a mosasaur that is 15 meters (50 feet) long like the one on the show could travel 11.4 meters (37 feet) per second.

Uncovered Segment II: What Do We Really Know About Ammonites?[]

TBA

Fauna[]

Main[]

Scrapped[]

Trivia[]

Filming Locations[]

Filming locations for the episode were confirmed on "I Know Dino: The Big Dinosaur Podcast", Episode 446: Dinosaur-era Oceans and Darren Naish from Prehistoric Planet 2.

Miscellaneous[]

  • While the second segment of this episode is confirmed to take place in the Western Interior Seaway during the early Maastrichtian stage of the Late Cretaceous Period (around 72 million years ago), its exact setting remains unknown. Based on the presence of the scrapped animals, the segment could be, at least during the planning stages, either within or near the Moreno Formation in San Joaquin County, California, USA (where Hydrotherosaurus is known from) or the Pierre Shale, a formation in the Great Plains, east of the Rocky Mountains, stretching from Pembina Valley in Canada to New Mexico (where the last and largest species of Dolichorhynchops, D. bonneri, is known from).
  • After its equivalent in the previous season, Coasts (which has only its first segment featuring dinosaurs, specifically T. rex, not counting extant avians like the ostrich and the emu in the accompanying Uncovered segment), this episode features the fewest number of dinosaur species, as it only has Hesperornis in the second segment, and juvenile Pyroraptors in the third segment.
  • This is the second episode in the series that does not feature pterosaurs (though some seem to have been planned to appear initially), following Ice Worlds of the previous season. Coincidentally, both episodes are the fourth in their respective seasons.
  • This episode was "voted the unluckiest episode to shoot" by the staff, given the turbulence of the waters and various weather disturbances.[PhP 1]
    • On the 27th of August, 2021, Hurricane Ida struck the Grand Cayman Island (used as the shooting location for the first and fourth segments), leaving the filming crew stuck in the ground floor of their accommodation with no food or running water for several days.[PhP 1]
    • A Mediterranean cyclone struck the Balearic Islands, the shooting location for the fifth segment of the episode.[PhP 1]
    • While shooting for the sixth segment (which is set in the López de Bertodano Formation in Antarctica) in Sweden, the temperatures were originally around -27 to -28 degrees Celsius (-16.6 to -18.4 degrees Fahrenheit), leaving a lot of ice without holes (which the staff needs to show the Morturneria poking their heads out of the water). Overnight, the temperature went up to 3 degrees Celsius (37.4 degrees Fahrenheit), causing all the ice in the area to have holes, making it hard to find ice sheets without gaps, which the episode needed to present as a danger that may prevent the Morturneria from rising to the surface to breathe. Eventually, as the wind picked up, the temperatures rose up to 12 degrees Celsius (53.6 degrees Fahrenheit) in under a week, causing all the ice meant for the scene to break up and melt.[1][PhP 1]

References[]

General[]

  1. ↑ Blending CG Creatures & Wildlife Photography to bring Lost Giants to Life

Dr. Darren Naish[]

  1. ↑ 1.0 1.1 The fourth segment of Oceans takes place in the Darwin Rise.
  2. ↑ In Oceans, parts of a seamount closest to the surface of the water was supposed to feature rudist reefs. Producer Paul Stewart started the idea, and even brought in his rudist fossils, but they were unable to fit these bivalves into the story of Coasts. Rudists are small, unusual bivalves that came in different shapes and sizes. They formed unusual reefs that would have been hostile to other organisms. There were even physical models made for them, but they were unfortunately never featured in the series.

Prehistoric Planet[]

  1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 I Know Dino: The Big Dinosaur Podcast, Episode 446: Dinosaur-era Oceans and Darren Naish from Prehistoric Planet 2
  2. ↑ Hesperornis concept art for Prehistoric Planet featuring Dolichorhynchops
  3. ↑ 3.0 3.1 Prehistoric Planet: Bait ball

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