Blue Planet II

Spinner dolphins gather together in super pods of 5,000 individuals to increase their chances of finding food in the vast open ocean. These dolphins rely on their echo-sounding calls to locate prey, such as the lanternfish off the Pacific Coast of Costa Rica. Once they happen upon the lanternfish congregations, the dolphins swim beneath the shoal, trapping the prey at the surface and forcing them to cluster together, making it easier for the dolphins to feast on this fleeting food source.

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Lanternfish are a small but abundant species in the ocean, and play a crucial role in the marine ecosystem. These fish typically surface at night to feed on plankton, but occasionally rise during the day to spawn. One such rare event, occuring off the Pacific coast of Costa Rica, attracts a multitude of predators, such as spinner dolphins, yellowfin tuna, Chilean devil rays, and sailfish. As the dolphins herd the shoal towards the surface, a feeding frenzy ensues and the sea begins to boil and froth with thousands of small fish attempting to evade their predators.

Yellowfin tuna have detected the immense shoal of lanternfish off the Pacific coast of Costa Rica. They must take advantage of this valuable feeding opportunity even as other predators, such as dolphins, rays and sailfish are attracted to the same bounty. Speeding through the water at over 40 miles an hour, the tuna charge into the shoal, taking advantage of the dolphins' efforts to pin the lanternfish to the surface.

The Chilean devil ray joins predators such as spinner dolphin, yellowfin tuna and sailfish in hunting a massive shoal of lanternfish off the Pacific coast of Costa Rica. Although slower swimmers compared to the other predators, the rays make up for it with their immense mouths. When they finally reach the shoal, they open their mouths wide and scoop up hundreds of lanternfish at once.

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The sailfish, one of the fastest fish in the sea, is a skilled predator that joins the hunt for the immense shoal of lanternfish off the Pacific Coast of Costa Rica. Arriving after dolphins, tuna, and rays, the sailfish expertly pick off the survivors of the shoal, now dispersed by the feeding frenzy.

A pod of sperm whales hangs vertically and motionless, resting between feeding sessions. During this time, even their young calves must patiently wait for their mothers to awaken to receive nourishment. These calves are often covered in suckerfish, but doesn't yet possess the strength to remove them on its own. Once the family is rejuvenated, they continue their journey through the vast ocean.

Suckerfish attach themselves to larger marine animals, such as whales, sharks, and in this case, a sperm whale calf. While the young calf may be irritated by their presence, it cannot yet rid itself of them.

Sperm whales are remarkable deep-diving hunters, diving up to 800 meters in search of squid. They use a series of heavy breaths to saturate their blood with oxygen before diving, and employ sonar through a series of clicks to locate their prey. Sperm whale calves, however, struggle to keep up with their mothers and may take up to six years to master the art of deep diving. In the meantime, they rely on their mother's rich milk for sustenance, consuming a bathful of it each day.

A green sea turtle hatchling embarks on a journey from the crowded coastal waters to the vast open ocean in search of safety and sustenance. Initially feeding on plankton, the baby turtle will soon require a more substantial diet. It may join communities of other young marine castaways, often centered around floating objects, such as logs or debris.

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A young Pacific hawksbill sea turtle in the open ocean has found refuge floating community centred around a log. Here, it can feed on plankton, seaweed, and barnacles that have attached themselves to the log. Even here, the turtle has to avoid predators such as a juvenile silky shark. Young turtles can remain in these communities for several years until they reach adulthood.

Goose barnacles that have attached themselves to logs and other debris floating in the open ocean. They are a food source for other young marine castaways, such as sea turtles.

A shoal of young pufferfish congregates at a floating log. Objects like these provide a refuge for communities of marine castaways on the open ocean.

A juvenile ocean-going silky shark comes across a floating log that a young hawksbill turtle is using as a refuge in the open ocean. The shark is still learning what types of prey are suitable and nips at the turtle before deciding against pursuing it further.

Blue sharks rely on ocean currents and their broad wing-shaped fins to travel over 5,000 miles a year in the open ocean searching for food. These sharks can go without food for up to two months and use their keen sense of smell to find a meal. A sperm whale carcass in the Azores leaks fatty oils into the surrounding waters, drawing in multiple blue sharks.

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A great white shark happens across a floating whale carcass off the coast of South Africa. The energy-rich whale blubber is a crucial part of the great white's diet. Only once the highly territorial great white has had its fill, can smaller sharks feed on the remains.

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Some jellyfish reach exceptionally large sizes, including the lion's mane jellyfish which can grow up to two metres in diameter.

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The ability of jellyfish, such as the moon jelly, to reproduce rapidly in areas abundant with plankton has made them one of the most common lifeforms on Earth.

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The ability of jellyfish, such as the sea nettles, to reproduce rapidly in areas abundant with plankton has made them one of the most common lifeforms on Earth.

Though the Portuguese man o' war resembles a jellyfish, it is in fact a siphonophore. It floats using a gas-filled bladder with a vertical membrane, which serves as a sail to navigate through the waves. Its long tentacles, reaching up to 30 meters, are armed with thousands of stinging cells capable of killing fish and, in rare cases, humans. Using its specialised tentacles it is able to capture and digest over a hundred small fish in a day.

Some fish, such as this species, exhibit a remarkable resistance to the stings of the Portuguese man o' war.

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Only recently have we started to uncover where female whale sharks go to give birth. A pregnant female can carry up to 500 babies in her belly. When one female arrives at Darwin Island in the Galapagos, she is greeted by several silky sharks, which bounce against her rough skin to remove parasites. To protect her young from potential predators, she dives to depths of around 600 meters, where it is believed she releases her offspring in relative safety. The nutrient-rich waters around the island make this area a likely nursery for these gentle giants.

Scalloped hammerhead sharks gather in massive numbers around the nutrient-rich waters of Darwin Island in the Galapagos. These gatherings predominantly consist of females, suggesting that they assemble to breed.

In a fascinating interaction between two shark species in the waters of Darwin Island in the Galapagos, we see several silky sharks rub up against a massive female whale shark. It's possible that the whale shark's rough skin helps the silky sharks rid themselves of any parasites they may have acquired.

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Wandering albatross spend as much as a year at sea searching for foos, gliding effortless on their wings, spanning three and a half metre across. These birds do return to land to breed, however. On South Georgia, we see a pair of albatross reuniting at the same nest site they have used throughout their lifelong partnership. To give their young the best possible start in life, both parents tirelessly search thousands of square miles for food, even during the harsh Antarctic winter. After nine months of nurturing, the chick has shed its downy coat for flight feathers and is finally ready to leave the nest. For these elderly albatross parents, it marks the end of their journey; they will never recover from their exertions.

A short-finned pilot whale mother carries the body of its new-born calf, days after it has died. Plastic pollution is a significant threat to marine life. It can introduce toxic chemicals into the food chain, which accumulate to lethal levels in predators at the top, such as pilot whales. It's possible that this calf was poisoned by its mother's contaminated milk. A tragic loss like this affects the entire pod; cetaceans possess large brains and are able to experience emotions and form strong bonds with their pod members.