Ocean Secrets: What Science Hasn’t Figured Out About the Sea

In the vast and immense bodies of water covering our planet, where light is only close to the surface and darkness and mystery are found in the deep, many creatures rely on size, speed and strength to survive. But some have evolved another trait, perhaps the most powerful of them all. Family. Somewhere in the North Atlantic Ocean, these giants are sleeping. Female sperm whales are highly social. They live in family groups called pods and work together to raise their young, while adult males travel alone or move from pod to pod. Like all mammals, whales need to breathe air, so they sleep just below the surface and come up for air in between short naps. Sperm whales spend just 7% of their time asleep, less than any other mammal on Earth. So it's rare to witness a family slowly waking up after a deep sleep. The females in this close-knit family group will stay together for 10 or more years. They share knowledge, sounds and hunting skills with one another. Learning from each other helps them develop a deep bond and sense of belonging, critical for the survival of their family and their species. Sperm whales live in an environment totally different from ours. They see the world through sound. And though it may sound quiet to us, the ocean is a noisy place. And sperm whales are the loudest animals found anywhere on Earth. They use a system of clicking sounds to communicate and strengthen the bonds between females. Their clicks are so powerful, they can transmit messages over hundreds of miles, even across vast oceans. Usually, though, the clicks are used like a kind of sonar to find food. A sperm whale spends most of its life at the depths of over 3,000 feet, hunting for squid in total darkness. About 60 million years ago, a hoofed, wolf-like mammal traded its terrestrial lifestyle for an aquatic one. Over time, it evolved into many different forms, including all 80 species of whales, dolphins and porpoises we know today. In the warm waters around the Bahamas, a pod of spotted dolphins is playing and bonding. Calves don't have spots like their parents, so it's easy to mistake them for small bottlenose dolphins. Their spotted patterns begin to develop after their first birthday. Spotted dolphins are extremely social animals. To communicate with each other, they blow bubbles through their blowholes and use whistles, clicking and other sounds. Dolphin calves are born with very few survival skills, so they rely on their mothers to teach them almost everything. The bond they share is the strongest relationship these dolphins will have in their lifetimes. Pregnant females begin teaching their calves even before they're born. In the weeks before and after they give birth, they repeat their own signature sounds over and over. This teaches the newborn calf how to recognize its mother's voice so it can bond and imprint to her. The pod is highly protective over pregnant females, and during this time, they help by quieting down. Once a calf is born, the real education begins. Moms teach their calves how to breathe, swim, and of course, have fun. With so much to do, new moms get little sleep in the first few months. They nurse their young three times longer than any other large whale, and with help from the rest of the pod, mothers take care of their calves for up to five years. With so much maternal care and support from the group, spotted calves are given everything they need to succeed in life. Unlike the spotted dolphins that live in large pods, there are others characterized by having a smaller family nucleus. In the coastal zone of the South Pacific, where the waves crash against the cliff, another family unit is going about their day. At just ten pounds and three feet long, when full grown, marine otters are the smallest marine mammals in the world. These marine otter pups aren't old enough to hunt for themselves yet, so they spend their days doing what otter pups do best, playing, waiting for mom, and being cute. Soon, these pups will have to go off on their own, but for now, there's nothing more important to them than their mother, and nothing she wants more than to spoil her pups. Otters are intelligent and social animals, so there's always time to bond and play. With a very fast metabolism, otters need a near constant supply of calories to keep warm. With little body fat, they must hunt several times a day to stay alive in these cold South Pacific waters. To be a good otter mom, you must be an excellent hunter so you can provide for your pups. To hunt in this environment requires skill, experience, and patience. Fortunately, this otter mom knows exactly where to look to find tasty prey like shrimp and fish. Otters need to consume 30% of their body weight every day, and with two pups at home, waiting for dinner, she can't go home empty handed. After their afternoon playtime, the pups are hungry. They're in luck. Mom has brought back a delicious crab. These young otters eat just as much as an adult, so she must continue to provide food almost around the clock. She knows this will not be enough and heads out for the second course. Mom must eat too. And while the pups are off playing on the rocks, she catches a shrimp and enjoys a little peace and quiet. Winding along the Pacific coast of South America, the humble current emerges from the deep. It brings with it nutrients that form the base of the entire food web. But animals depend on more than just food for survival. Like us, they need shelter to protect themselves and raise their young. A colony of South American sea lions has gathered on this rocky shelf, like they do every year for a very special occasion. They're about to bring new life into the world. During pupping, a female will call to her pup, and the pup should instinctively reply. But something is wrong. Pups are usually born head first, and the protective membrane didn't break. If she can't remove it in time, her pup could suffocate. She calls to it and waits. Her pup is alive and well, but coming into this world is only the first of many dangers it will face. Newborns are especially vulnerable. Some mothers will stop eating for seven days to nurse and watch over them around the clock. The bond between a sea lion mother and her pup is remarkably strong. Over the next 12 months, she will do everything she can to feed and protect her young. The presence of a newborn pup in the colony has attracted a hungry visitor. Turkey vultures have an acute sense of smell, which they use to find food. Their noses lead them straight to the sea lion's discarded placenta. Kelp gulls are quick to join the feeding frenzy. As in most mammals, the placenta nourishes and protects the sea lion pup as it grows inside its mother. Evolving around 120 million years ago, this important organ enabled mammals to achieve tremendous evolutionary success. Placenta allows for newborns to be more fully developed at birth, giving them a greater chance of survival. After pupping is over, placenta is useless to the pup, yet it provides a rich source of protein, iron, and other nutrients for a variety of animals. Taking advantage of resources like food and shelter is key to surviving in the ocean. What's left of the placenta will eventually dissolve, returning its nutrients to the humble current and giving life to an entire ecosystem. Just below the tide pools and boulders that protect the sea lion colony, an underwater forest provides shelter for creatures large and small. Fish use kelp forests as spawning grounds or as nurseries for their young, while seabirds, sea lions, and other marine animals seek out refuge here from predators and storms. But pelagic species, those that live in the open ocean, must find other ways to protect themselves. Bait balls are a double-edged sword. While they provide protection to small fish like sardines, silversides, and anchovies, they're also an easy target not only for predators below, but also from above. Peruvian boobies, with their excellent binocular-style vision, are always on the lookout for their next meal. They can scan the surface for any kind of disturbance. Once a bait ball is spotted by one, the others quickly join in. In the cold, nutrient-rich waters of the southern Pacific Ocean, the humble current provides a steady stream of food for many species. Close by, on a small, uninhabited island off the coast of Chile, a Peruvian booby colony finds protection on the steep cliff sides. The chicks have yet to grow their adult feathers, so they're completely dependent on their parents. Chicks require an almost constant supply of food, so parents work together to make sure they never go hungry. While one parent stays with the chick, the other goes in search of food. And there's nothing better than working the bait ball shift. With power, speed, and precision, the booby chooses a target from 100 feet in the air, tucks its wings back, and plunges headfirst into the bait ball. Air sacks in its skull, cushion the impact, and a strong, pointed beak pierces the water at breakneck speeds. There's not a moment to waste, as the bait ball can vanish just as fast as it appeared. The chicks are hungry, and the shift change must happen quickly. As one parent returns to the nest, the chicks eagerly anticipate their next meal, and the other parent prepares to take flight. The mom has just arrived with a stomach full of food for her chicks, and dad is ready to feed on what's left of the bait ball. For boobies, family is everything. Booby pairs mate for life, and will work together like this until their chicks are old enough to leave the nest and feed on their own. Some birds never forget the place that they were born. On the North Atlantic coast, year after year, these common terns come back to the same colony where they hatched. They migrate south from the Arctic to breed and raise their young. The males reach the colony first to choose their nesting territories, with their mates arriving shortly after. But if a female is more than five days late, the male will find another mate. After an elaborate aerial courtship, the female accepts her mate and allows him to breed with her. She chooses the father of her chicks by the quality of his wing feathers. After mating, the female lays one to three eggs. Since their nests are out in the open, their eggs are speckled, camouflaged to look like petals. Both parents take turns incubating the eggs. But when unwelcome visitors get too close, fathers go on the defense. Males aggressively protect their nests until all their chicks have fledged, and the colony works together to drive off would-be predators. Common terns tend to nest with other coastal species, like Arctic terns. These birds make the longest migration known in the animal kingdom. After spending the southern summer on the Antarctic coast, they migrate some 25,000 miles north to reach their breeding grounds. They experience two summers each year, and more daylight than any other creature on Earth. But for these world travelers, the long voyage to start a family is well worth the effort. Parents returning to the nest with fish lure their chicks out of hiding with a special call, almost like a dinner bell. By about two weeks old, siblings can also recognize each other's calls, which helps form important family bonds. Both parents work around the clock to feed and protect their chicks for about a month. After chicks fledge from the nest, the whole family takes to the sky. The parents help their young make the long journey back to Antarctica. After migrating, most young terns stay in the southern hemisphere until they are two years old. Then, they make the trip back to their birthplace on their own, without help from their parents. How the terns find their way home, no one knows for sure, but life always finds a way. They are driven, like other species, to find a mate, start a family, and give their young everything they can. But it's not always the same. Nature continually challenges. Back on the South Pacific coast, male sea lions, called bulls, actively patrol their territories. They'll go to extreme lengths to protect their harem of females, waging violent battles against any who dare to trespass. They can grow to over nine feet and weigh up to 800 pounds. Pushed to the edge of the colony, this intruder takes a submissive stance. But to the dominant bull, it's not enough. As long as he's on the rocks, he poses a threat. Males have huge heads with well-developed manes and are three times the size of females. Fights most often break out between bulls at the beginning of breeding season. Males who arrive early get access to more females and will have more pups. The more females that are in heat, the more fights there will be between bulls. Males that can't win their own territories and harems will band together and stage group raids to steal females. These young males are practicing for when they will have to fight to have a family of their own. As these young sea lions playfully spar, a decisive battle begins. A younger male has tried to steal an older bull's harem. But the old bull is not as strong as he used to be. With a bloodied mane and a bruised ego, he concedes defeat and retreats. Breeding season is a stressful time for everyone, especially the bulls. Whether they're defending a harem or stealing one, eventually older bulls can't compete and they simply fade away. What was once his safe haven is now no more. He must find another place to live, and a life alone can be very dangerous. Far from the sea lion's colony, there's a place which also provides shelter for many species. The warm, sunlit waters around the equator hold one of the most diverse ecosystems on the planet. Covering less than 1% of the Earth's surface, but home to one quarter of all marine species, coral reefs are the rainforests of the sea. Reefs are made up of colonies of coral polyps, tiny animals that secrete hard exoskeletons to support and protect themselves. The beautifully intricate structures they create provide food and shelter to over a million different plants and animals. And millions of people also depend on coral reefs for food, income, medicines, and protection from storms. But everywhere, coral reefs are under attack. Overfishing, pollution, invasive species, and climate change are wreaking havoc on these important places. Working to keep them healthy are the very creatures that live here, each of which plays a unique and vital role on the reef. The more species in an ecosystem, the more resilient it will be to change, and the greater chance it has to survive. Plant-eating fish, like blue tangs, have one of the most important jobs on the reef. They travel in schools and graze on algae, which compete with corals for access to sunlight. Some corals even send out emergency help signals when threatened by toxic algae. In response, fish come to the rescue. By trimming back algae, these fish save coral from being suffocated or poisoned by their deadly competitors. To keep blue tangs and other herbivorous animals in check, the reef relies on predatory fish like jacks, barracudas, and sharks. Borsight jacks prey on small fish, shrimp, and other invertebrates living amongst the coral. They often school around Caribbean reef sharks, one of the most formidable predators on the reef. But the jacks are unfazed. Even though a reef shark could easily swallow them whole, they know that reef sharks hunt mostly at night and pose little threat during the day. As apex predators, sharks keep the reef healthy by weeding out animals that are weak and sick. As many more sharks begin to arrive, the smaller fish are getting skittish. Whatever they're here for, it can't be good. With danger around every corner, growing old on the reef isn't easy, especially for animals on their own. Sea turtles have been around for 100 million years since dinosaurs roamed the Earth. Yet today, hawksbills are critically endangered. Entanglement in fishing nets, plastic pollution, and poaching have caused their numbers to plummet. Found in the tropical waters of the Atlantic, Pacific, and Indian Oceans, these graceful marine reptiles thrive on coral reefs where there are abundant sponges, jellyfish, and sea anemones. They are even able to consume prey that would kill other animals, like Portuguese man o' wars and toxic sponges. Their narrow heads and hawk-like beaks help them extract food from the crevices along the reef. Because of their tough shells, their only predators are sharks, crocodiles, and very large octopuses. When you don't have a shell, you must have another way to protect yourself. A group of reef squid is going about their day. At night, they'll leave the group to feed on their own. They have the largest eyes of any animal on Earth relative to body size, which they rely on to find prey in the dark. Caribbean reef squid are voracious hunters, devouring 60% of their body weight in fish, crab, and shrimp every night. Within the group, each squid has a specific role. Some are constantly on the lookout for predators and warn the others of approaching danger, while other larger squid are responsible for defending the shoal. By controlling the pigment in their skin, they can change their color and pattern to confuse prey and communicate with each other. Using a language of visual signals, they can send one message to a squid on their right while sending a different message to a squid on their left. And when a predator gets too close, they can change to a pale color and jet away. In the deeper waters just beyond the coral reef, a group of sharks is circling. Most sharks live a solitary existence, but some are more social. These lemon sharks have gathered here together to take a break from swimming and rest. It was once believed that sharks must keep moving in order to breathe. Now we know they can rest along the bottom as long as the current flows through their gills. Other species find time to relax at cleaning stations. Places on the reef where tiny fish and shrimp feast on bacteria and parasites living on other fish. Another cleaner by trade, the parrotfish, is constantly tidying up the reef. Its teeth are fused together, so its mouth looks like a parrot's beak. A parrotfish uses this beak to scrape algae off rocks and get to the even smaller algae living inside coral polyps. In its throat is another set of teeth that grind up the coral's skeletons. It excretes fine sand that carpets the ocean floor and builds beautiful white sand beaches. A parrotfish will graze constantly throughout the day, producing 700 pounds of sand per year. What otherwise would be a rocky seafloor now provides places for other creatures to hide. Just off the coast of Mexico, a bull shark scans the ocean floor, hoping to detect tiny electrical signals that could indicate its prey. Bull sharks are aggressive predators and very sloppy eaters. For other smaller fish, staying close by means an easy meal. But if they get too close, they risk becoming the meal. A tiny blue runner has taken up a daring position, caught up in the shark's momentum and only inches from its jaw. If it's lucky, the little fish will fall to the side, taking a more humble position. Making a quick escape, the blue runner joins the remoras, which know better than to try to outrun a bull shark. For those looking to take the slower, more scenic route, a whale shark is the perfect mode of transport. Growing up to 60 feet long, the whale shark is the largest shark and largest fish in the world. Despite their massive size, they feed on some of the smallest animals in the sea, so it takes a while to get their fill. Whale sharks eat plankton mostly, but today they timed their trip here to coincide with a mass spawning of fish. As the eggs float to the surface, the sharks open their mouths up to five feet wide. They force huge amounts of seawater through their humongous gills, which separate food from water. Their slow and gentle nature makes them easy targets for predators. And with so much time spent on the surface, they're often hit by passing ships. Blue sharks will prey on juvenile whale sharks, but only orcas dare to take on an adult. The pattern of the spots on their backs is unique to each individual. This cryptic camouflage is also their first line of defense. But their most protective adaptation is their tough skin and thick layer of cartilage. This amazing armor can be further stiffened when muscles just below are tightened. But their underbellies are still soft and vulnerable. This legendary creature most often lives in the open sea, although it can sometimes be seen near tropical islands where other armored animals live. On several islands in Indonesia, mangrove forests conceal the most legendary creatures of all. Dragons. Growing up to 10 feet long and weighing up to 150 pounds, Komodo dragons are the largest living lizards on Earth. As the top predators on these islands, they eat everything from deer and pigs to carrion and even large water buffalo. Komodo dragons hunt by ambushing their prey as it passes by. Using their powerful limbs, sharp claws and serrated teeth to create huge, gaping wounds. The dragon's venom glands are packed with toxins and anticoagulants, which increase blood loss and quicken death. Komodo dragons routinely gorge themselves, eating up to 80% of their body weight at one time. Mating season begins with males wrestling each other for females and territory. Females aggressively fight back during courtship, so males have to restrain them while mating to prevent injuring themselves. Sometimes Komodo dragons form monogamous pair bonds, a very uncommon behavior for lizards. In addition to sexual reproduction, females are able to reproduce by themselves, a process called parthenogenesis. Although they are only able to produce male offspring in this manner, this ability likely evolved to enable a lone female to colonize a new area. First by producing male offspring on her own, and then by mating with them to produce both male and female offspring. When they are young, Komodo dragons live in the trees to stay away from predators and cannibalistic adults. As much as 10% of an adult dragon's diet consists of juvenile dragons. They take around 9 years to reach maturity, and can live for up to 30 years. In some places, the dragons live alongside villagers, a relationship that is rooted in local legend. As the story goes, a princess on Komodo Island once gave birth to twins, a human boy and a dragon girl, but decided to raise them separately. Years later, while hunting, the boy saw a dragon in the woods and aimed to kill it. But the spirit of his deceased mother appeared and told him it was his sister. Humans and dragons are said to have coexisted peacefully ever since. Perhaps the most ubiquitous creature in human mythology is the whale. Nearly every coastal society throughout history has passed down stories about whales. Some believe they are gods or heavenly spirits that bring fortune and peace. Blue whales were not well understood. Along with other large whales, they were considered to be sea monsters. In old Icelandic sagas, different whale species were imagined as being either good or evil. While evil whales would swallow entire boats full of fishermen, the blue whale was the protector of the fishing boats. It would circle a boat three times to warn the crew of danger before scaring away the evil whales. And if there were more than three, the blue whale would explode, killing all the evil whales with it. Reaching up to 100 feet and 380,000 pounds, the blue whale is the largest animal to have ever lived on Earth. Its tongue alone weighs 6,000 pounds, and its mouth can hold up to 200,000 pounds of food and water. At birth, newborn calves weigh nearly 6,000 pounds. They drink 100 gallons of milk each day for seven months, gaining as much as 200 pounds a day. An adult blue whale's heart weighs 400 pounds and can beat as few as two beats per minute when diving. This helps to conserve oxygen so they can stay underwater for longer periods. Like other baleen whales, the blue whale's diet comprises of tiny crustaceans called krill. To meet their daily energy requirements, they consume up to 8,000 pounds of krill per day. Blue whales gorge themselves in Antarctic waters before heading north to warmer waters near the equator to breed. The massive size of baleen whales evolved only 4.5 million years ago, when a change in Earth's climate caused krill and zooplankton populations to explode. Baleen whales were able to eat more than ever before, but they also had to work harder for it. Because these explosions of food happened seasonally, the whales had to migrate thousands of miles between food sources. Bigger baleen whales were better able to survive the long migrations, while smaller whales died out. These blue whales, and many other magnificent sea creatures, have come to mean different things to different people. For some, blue whales are a symbol of the ocean itself. Powerful and peaceful, beautiful and mysterious. Many cultures throughout the world share a deep sense of stewardship and a profound spiritual connection to the sea and its animals. The myths and legends they have passed down reflect a complex and sometimes contradictory relationship with the sea. Yet the simple truth is that life itself arose from the ocean. And though often overlooked, every living thing today depends on the ocean to sustain life on Earth. Regardless of language or latitude, tales of the sea must endure, for although the stories will change over time, our respect and awe for this world of oceans, and its creatures, should never fade.