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Episodes
- S1 E1 - Water: The Source of LifeFebruary 1, 201835minSo much of what we take for granted about our world (from our body's access to and use of nutrients, to our planet's liquid oceans, to the ice floating in your glass of soda) is a direct cause of the structure and polarity of H2O. Learn how those specific properties make water the essential ingredient for life as we know it. #Science & MathematicsFree trial of The Great Courses Signature Collection or buy
- S1 E2 - Ocean Currents and Why They MatterFebruary 1, 201833minNo matter where you live, your climate, weather, and even available foods are determined to a great extent by ocean circulation. The uneven heating of the Earth by the Sun and the Coriolis effect result in vast circulation cells of air above the Earth, the movement of huge water masses in the oceans, and resultant "hot spots" of marine life.Free trial of The Great Courses Signature Collection or buy
- S1 E3 - The Origin and Diversity of Ocean LifeFebruary 1, 201837minHow and where did life begin on Earth? The existence of both photosynthetic and chemosynthetic food chains points to the possibility that life could have originated through two different paths. While many questions remain unanswered, two things seem certain: Life began in the oceans, and bacteria are the most successful organisms on the planet.Free trial of The Great Courses Signature Collection or buy
- S1 E4 - Beaches, Estuaries, and Coral ReefsFebruary 1, 201830minBeach organisms exist with the constantly changing winds, waves, and tides (sometimes underwater, sometimes fully exposed to the air). Life in estuaries, where rivers meet the oceans, face constant fluctuations in environmental salinity. And hard corals are continually pummeled by wave action. Yet each of these physically challenging environments can be diverse and fecund ecosystems.Free trial of The Great Courses Signature Collection or buy
- S1 E5 - Life in Polar and Deepwater EnvironmentsFebruary 1, 201829minPhytoplankton form the base of almost all marine food chains, including that of the blue whale, the largest animal known to have ever existed. But far below the penetration of sunlight, a very different and only recently discovered food web relies solely on the chemosynthetic ability of bacteria.Free trial of The Great Courses Signature Collection or buy
- S1 E6 - Phytoplankton and Other AutotrophsFebruary 1, 201829minWhen we think of healthy marine ecosystems, we should be thinking about phytoplankton. In many ways, we owe our existence to these diatoms, dinoflagellates, green algae, cyanobacteria, and others. Not only do scientists believe they are the ancestors of terrestrial plants, but phytoplankton continues to produce about half of all the oxygen available in our atmosphere today.Free trial of The Great Courses Signature Collection or buy
- S1 E7 - Invertebrate Life in the OceanFebruary 1, 201833minThe vast majority of animals on our planet are the gloriously diverse invertebrates. From microscopic organisms to the crab with a three-meter leg span, marine invertebrates exhibit enormous variety in form and function. They include sessile and mobile organisms, free-living and parasitic. They live at the surface and within the ocean floor sediments.Free trial of The Great Courses Signature Collection or buy
- S1 E8 - An Overview of Marine VertebratesFebruary 1, 201833minMammals are certainly represented in ocean life, but which species should be identified as "marine" when considering ocean productivity? The extremely complex marine food webs maintain long-term stability, even as they undergo natural perturbations over time. But when Homo sapiens enters as an apex predator, productivity can deteriorate, and systems can even collapse.Free trial of The Great Courses Signature Collection or buy
- S1 E9 - Fish: The First VertebratesFebruary 1, 201832minThrough 550 million years of evolution, fish have developed a wide variety of adaptations to the unique demands of living in a watery and mostly dark world. Learn how gills, swim bladders, bioluminescence, chemosensory glands, echolocation, and electrolocation have allowed fish to succeed in almost every type of ocean environment. Which fish are our ancestors? You might be surprised.Free trial of The Great Courses Signature Collection or buy
- S1 E10 - Marine Megavertebrates and Their FisheriesFebruary 1, 201833minWhile humans have been fishing for hundreds of centuries, we have only recently had a significant impact on marine food webs. Industrialization has led to problems with by-catch and overexploitation of resources. Today, we are creating trophic cascades with long-term impacts we do not yet understand.Free trial of The Great Courses Signature Collection or buy
- S1 E11 - Sharks and RaysFebruary 1, 201834minFish certainly have good reason to fear these top-of-their-game predators, with their multiple rows of teeth and ability to detect electrical current better than any other animal. But while four species have been known to assault humans with no provocation, almost 99 percent of the many hundred shark species would rather swim away from us than attack.Free trial of The Great Courses Signature Collection or buy
- S1 E12 - Marine Reptiles and BirdsFebruary 1, 201831minWhile the reptilian evolution of the amniotic egg allowed animals to move completely from the sea onto land, some reptiles retained strong marine ties. These include sea turtles and sea birds whose wide variety of adaptations allow for drinking saltwater, remaining underwater for long periods, and flying great distances using very little energy.Free trial of The Great Courses Signature Collection or buy
- S1 E13 - The Evolutionary History of WhalesFebruary 1, 201830minMarine mammals did not evolve from marine species. Rather, they evolved from land mammals who found a plethora of "suddenly" open ecological niches when the dinosaurs became extinct. Today's marine mammals might resemble each other because convergent evolution has led to similar adaptation. But best as scientists can tell, they have five separate lineages and no single common ancestor.Free trial of The Great Courses Signature Collection or buy
- S1 E14 - The Taxonomy of Marine MammalsFebruary 1, 201831minThrough tens of millions of years, evolution has resulted in a fascinating array of marine mammal adaptations. With the ability to process thousands of gallons of water each day or dive to a depth of almost three kilometers, and with numerous methods of locomotion or extraordinary social behaviors, these whales, porpoises, phocids, and more can thrive in varied environments around the globe.Free trial of The Great Courses Signature Collection or buy
- S1 E15 - How Animals Adapt to Ocean TemperaturesFebruary 1, 201831minIf you've ever jumped into frigid water, you quickly realize humans are definitely not adapted to life in the sea. What are we missing? In a word, it's blubber. In fact, blubber is such a successful insulator that marine mammals have evolved internal and external means for getting rid of all that heat, possibly even including planetary migrations.Free trial of The Great Courses Signature Collection or buy
- S1 E16 - Mammalian Swimming and BuoyancyFebruary 1, 201828minFor all practical purposes, terrestrial mammals live on a plane. Marine mammals, on the other hand, navigate a more viscous, three-dimensional environment with all its opportunities and challenges. We understand their propulsion mechanisms fairly well. But how do they control their buoyancy to position themselves in the water column? We don't yet have the answers.Free trial of The Great Courses Signature Collection or buy
- S1 E17 - Adaptations for Diving Deep in the OceanFebruary 1, 201832minNot surprisingly, deep-diving marine mammals have evolved a physiology very different than our own. Adaptations including those related to blood chemistry, the location of stored oxygen, a variable heart rate, and articulated rib cages support the ability to go deep and stay long. But what about rising back up to the surface? How do they avoid getting "the bends"?Free trial of The Great Courses Signature Collection or buy
- S1 E18 - The Importance of Sound to Ocean LifeFebruary 1, 201834minSound travels much better in water than in air. In fact, low-frequency waves, such as those produced by certain whales, can travel through water uninterrupted for hundreds or even thousands of kilometers, allowing the animals to be "in touch" with their group over vast distances. But what happens when human-generated sound gets in the way?Free trial of The Great Courses Signature Collection or buy
- S1 E19 - Food and Foraging among Marine MammalsFebruary 1, 201830minTwo things are clear: Almost all marine food webs are based on microscopic photosynthesizers, and only a small fraction of the energy available at any trophic level becomes available to the next level. Adaptations such as baleen, ventral pleats, and unique tooth morphology allows these large animals to meet their energy needs.Free trial of The Great Courses Signature Collection or buy
- S1 E20 - Marine Mammal Interactions with FisheriesFebruary 1, 201831minWith plastic and nylon lines and nets becoming common in the last century, by-catch became an even greater problem for the marine mammals. When the media picked up the story in the mid-1960s, the public became engaged, and the Marine Mammal Protection Act was passed in 1972. But whale entanglement remains a problem, and some argue that even whaling was far less cruel.Free trial of The Great Courses Signature Collection or buy
- S1 E21 - Breeding and Reproduction in a Large OceanFebruary 1, 201833minSemi-aquatic marine mammals exhibit behaviors quite different than those who live fully in the water. In the former, an entire female community in one geographic area can come into estrus simultaneously and needs relatively few males to reproduce. In the latter, reproduction appears to be one of the driving forces of whale songs that can be heard over thousands of kilometers.Free trial of The Great Courses Signature Collection or buy
- S1 E22 - Behavior and Sociality in Marine MammalsFebruary 1, 201831minFrom individual whales that corral their confused prey to highly coordinated bubble-net feeding and aunts who "babysit," marine mammals have developed an extraordinary variety of social and hunting behaviors developed over millions of years. If the energy expenditure does not support the goal of passing on genetic material, natural selection will eventually drop the adaptation.Free trial of The Great Courses Signature Collection or buy
- S1 E23 - Marine Mammal Distribution around the GlobeFebruary 1, 201833minWith 60 million years of evolution on their side, marine mammals have adapted to the widest possible variety of marine ecological niches. Some live only in rivers or lakes, others only in waters over the continental shelves, and some in the open ocean. A few are even adapted to live at the poles.Free trial of The Great Courses Signature Collection or buy
- S1 E24 - Intelligence in Marine MammalsFebruary 1, 201835minWithin their own species, marine mammals have developed sophisticated communication. In captivity, we know they can be trained to learn rules, which indicates higher cognitive function. And even in the wild, we have documented some extraordinary instances of learning and cultural transmission of information. But is their intelligence comparable to our own?Free trial of The Great Courses Signature Collection or buy
- S1 E25 - The Charismatic MegavertebratesFebruary 1, 201832minAre marine mammals to be exploited as a resource? Or are they intelligent creatures to be revered with an almost religious admiration? Your answer might depend to some extent on your country and culture of origin. Our relationship with these impressive animals continues to evolve as we increase our understanding of their biology, cognition, and sociality.Free trial of The Great Courses Signature Collection or buy
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