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    Ocean Hall

Ocean Hall

The Hall of Human Origins ends at the back of Ocean Hall, a major exhibition space dedicated to marine animals. Because of the way the exhibits are organized, it’s better to start your tour at the front of the hall, near the archway to the rotunda. Work your way to the back of Ocean Hall from there, then turn right into African Voices.

Ocean Hall is a rectangle divided into three parts along its length. The middle part is the main hall, containing most of the large animal specimens and displays showing where they live. The smaller left side contains marine fossils dating back billions of years, illustrating how life evolved in the seas. The right side is broken into small, separate rooms with multimedia presentations about various ocean topics, such as how the oceans affect earth’s climate.

We’ll cover the main floor of Ocean Hall first. The front of the hall, just off the rotunda, contains presentations on the ocean’s biodiversity. Three large glass cases contain dozens of ocean animals, photos, and informative posters; in one case, a 20-foot tall, pink and white jellyfish extends out from its case, its head near the ceiling and tentacles flowing back inside the glass.

The goal of these biodiversity displays is to illustrate the questions scientists ask themselves when trying to organize and make sense of all these animals:

  • Who is it related to?
  • Where does it live?
  • How big (or small) is it?

Each display case has a section devoted to each question. In one of the Who is it related to? examples, there’s a nice set of around 3 dozen cone snail shells. These snails are small mollusks that live in shells that look like ice cream cone. What the display shows is that while the size, shape, and patterns of the cone vary quite a bit, all cone snails are closely related species.

Unofficial tip: What kid doesn’t want to know more about gelatinous zooplankton?

One of the Where does it live? sections holds the giant jellyfish, and uses the jellyfish to explain why where an ocean animal lives greatly affects its body shape. Jellyfish live near the ocean’s surface and in its water column, so its stinging tentacles hang down to capture fish below it. In contrast, anemones live on the ocean floor, and their stinging appendages float upward to catch their prey. That’s an indication that while they both use tentacles to catch food, jellyfish and anemones aren’t closely related.

Finally, the How big (or small) is it? sections are a bit unclear to us. There’s a section on how big sharks can get, for example, and one that compares the size of underwater kelp forests to tiny phytoplankton invisible to the human eye, but neither of them really explains how size factors in to a classification scheme. If there’s a rationale here that we’re missing, send us an email to let us know.

Above and around each of the biodiversity cases is a beautiful collection of animals, including sharks, leatherback turtles, lobsters, and giant crabs. The end of the biodiversity section has a nice poster on the ocean’s tree of life, showing how all living things in the oceans are related.

Following the biodiversity lesson is a presentation on sharks and humans. Before we get in to that, we must disclose, dear reader, your author has an irrational fear of sharks; he cannot snorkel in the open ocean without hyperventilating, and he considers the Sharknado films a documentary. That said, the Smithsonian notes that tens of millions of sharks are killed each year, often just for their fins (to use in soup). Sharks are a natural predator of rays, which each clams as part of their diet. So when there are fewer sharks to eat the rays, there are more rays and fewer clams for your dinner.

The center of Ocean Hall is dedicated to a 43-foot long North Atlantic Right Whale named Phoenix. Researchers have studied Phoenix from her birth in 1987 (she’s still alive as of this writing), and the displays in this part of the gallery show her growing up, her migration patterns, diet, and more. There’s also quite a bit on the whaling industry, from how it got started supplying whale oil for homes and industry, to the destructive impact on global whale populations. There’s also a section on the indigenous peoples who still practice small-scale whale hunts as part of their culture and diet.

The back of the Ocean Hall is dedicated to the open ocean. Separating this section from the rest of the hall is a long, thin, display case holding a giant squid, 36 feet long and weighing over 300 pounds. Once mistaken for a sea monster, people have claimed the existence of giant squid for thousands of year. But because they live in the deep ocean, very few specimens have been caught, and those that have were usually badly damaged or decomposed by the time scientists got to them. In fact, no photograph or video had ever been taken of a live giant squid prior to 2004 – unusual for something of this size. The one you see here comes from off the coast of Spain, in case you’re wondering where not to swim.

Beyond the giant squid, the hall is organized into three areas, depicting life in different ocean zones. In the shallow Surface Zone, sunlight is abundant and makes photosynthesis possible. That means plankton can live, and they provide food for a wide variety of other animals.

Sunlight has its downside, too, namely that you’re easily seen by the things that want to eat you. (It’s a similar situation to the African savanna and North American prairie.) To deal with this, animals have developed three strategies: sardines stay together in large schools, providing safety in numbers similar to how gazelles and zebra congregate; blend in with their surroundings, as do the transparent jellyfish and camouflaged sharks; and use speed to escape, like the Sargassum flying fish and Humboldt squid.

The next-deepest layer is the Twilight Zone, where there’s much less sunlight and food. Animals that live here have developed huge eyes to see better in the dark, and larger mouths (compared to their body size) for eating anything they can catch. Also, many animals found at these depths have developed some kind of bioluminescence: the anglerfish uses a glowing, antenna-like piece of skin in front of its mouth to attract prey; other creatures use bioluminescence to attract mates or scare off predators.

The bottom of the sea is known as the Deep Ocean, and is described by the museum as essentially a river of mud. There’s very little food here, and enormous pressure due to the volume of water above. Those mean that most bottom-dwelling animals are either stationary or slow-moving, with large mouths and watery bodies that float easily.

Another interesting thing found in the deep ocean, near hydrothermal vents, is chemosynthesis, the process by which tiny microbes make energy not from light (the way plants do with photosynthesis), but with chemicals from the earth’s core, exposed as vents when the earth’s crust moves. The idea that this was even possible was so revolutionary that it was only confirmed in the last 50 years, when deep-water submersible robots were able to reach the ocean floor.

Special Exhibits Gallery 4, at the back of Ocean Hall, is usually dedicated to photos, multimedia, and art related to ocean exploration. Past exhibits have covered the depths of the North Atlantic, coral reefs, and x-rays of fishes. The most recent exhibit was titled Portraits of Planet Ocean, and featured large-format color photos of tuna, sharks, whales, and more.

When you’re at the back of Ocean Hall, look to the right for a small room titled The Polar Oceans. This pathway, which goes through another series of ocean exhibits that lead you back toward the rotunda for the last part of the Ocean Hall tour.

Just before the Polar Oceans is a display of a coelacanth – a huge, lobe-finned fish thought to be extinct for 65 million years, until one was found off the coast of Africa in 1938. There are only two species of these fish alive, and they’re thought to have evolved into their present form around 400 million years ago. These fish have evolved a couple of interesting features, such as a hinged skull that allows the back of the head to move up, so the fish can eat larger prey; and lobed fins that move more like the legs of a trotting horse.

The Polar Oceans documents how fish, animals, and people have evolved to live with ice, constant cold, and darkness six months out of the year. How do animals survive in these temperatures? Many mammals, like polar bears and penguins, have developed an insulating layer of blubber fat that acts as insulation from the cold, especially when they’re in the water. (On land, the penguin stays warm with its feathers and by huddling together in groups.)

Fish, on the other hand, aren’t mammals – they’re cold-blooded – so they don’t have blubber. They still have to worry about not freezing, however, especially in icy waters. To do that, the bodies of many fish create their own antifreeze, in the form of a protein that binds to ice crystals and prevents them from expanding and causing cell death inside the fish. It only works for temperatures a couple of degrees below freezing, though, so you can’t squeeze a herring into your car’s radiator every winter.

The Shores and Shallows section of the hall contains some of the gallery’s best models. First up is a huge model of a Chesapeake Bay estuary, with real water, plants, and blue crabs. Illuminated panels next to the estuary show the lifecycle of the blue crab, which sees it travel throughout the bay to hatch, live, and mate. Besides the crab’s lifecycle, the estuary describes how animals in the estuary deal with varying levels of salt in the bay’s water, either by leaving temporarily, adapting their bodies to the higher salt content or flushing it out through specialized processes.

The other good model in this section shows beach erosion in action, in a clear, plastic-walled model filled with sand and water. The display notes that while some beach erosion happens naturally, it often happens where people have built homes and businesses. In those cases, some anti-erosion efforts can harm wildlife by pushing the effects off to other beaches where those animals build nests or mate.

The third display in this section is a coral reef packed with colorful fish and plants. It’s a mesmerizing collection of yellow angelfish, pajama cardinalfish, bicolor blenny, shrimp, anemone, and more, modeled after reefs found in the Indo-Pacific ocean. Kids love it, and there’s often a group of people standing wide-eyed in front of it. The thing to notice is how many different species share this relatively tiny space. They’ve evolved behaviors to share the space, by, for example, being active at different times of the day, or by staying within a relatively confined area of the reef.

If you’re touring the museum for half a day or less, take a break for lunch and then begin your tour of the second floor with our coverage below. If you’ve got more time, however, continue walking the rest of Ocean Hall.

The last two small parts of this side of Ocean Hall: Global Ocean Systems, showing how the oceans interact with earth’s atmosphere and soil; and Ocean Today, with the latest news on marine research.

Once you’re back at the front of Ocean Hall near the rotunda, bear left to the Journey Through Time area. The first display, on the evolution of predator fish, is based on the idea that you may not be having enough nightmares. We say that because all of these fish look terrifying, from the 25-foot long placoderms with spear-like jaws, the helicoprionid sharks whose mouth are described as “a buzz saw with fins”; the mosasaurids, 50-foot, air-breating, marine lizards; ammonites, the size of a grown man and the looks of a giant, angry snail with tentacles; and, of course, the giant great white shark.

Next up is a section titled The Explosion of Early Life, starting with 3.5-billion year old microbes, which gave off oxygen as part of their photosynthetic respiration cycle. These microbes were apparently the main form of life on the planet for a couple of billion years, up until around 600 million years ago, when many more diverse forms of life, including multi-celled algae, and hard-shelled animals started to appear.

Why did different forms of life appear, and how do we know it was 600 million years ago? Both answers may be “oxygen.” Billions of years ago, the earth’s atmosphere contained far less oxygen than it does today – as little as 1%. As these ocean-dwelling microbes gave off oxygen, the oxygen attached itself to iron and other organic elements in the water, keeping the oxygen in the seas. Eventually, the microbes produced more oxygen than the oceans could store, and the oxygen made its way into the atmosphere. Once in the air, free oxygen binds with iron on land to form iron oxide, and scientists have dated rocks with iron oxide to around 2.2 billion years ago. Based on those rock samples, there seems to have been a large jump in the amount of atmospheric oxygen around 600 million years ago.

Animals produce hard shells and skeletons in a process called biomineralization. All living things do this to some extent, and it may have evolved as a way for simple sea animals to excrete extra calcium carbonate from the ocean’s water. The evolution of hard shells was a big evolutionary advantage because it allowed for larger body sizes and the ability to move around in search of food and mates.

The basic body plans of all modern animals were set during the Cambrian period, 542 million years ago. There are some good displays in this section, showing the relatively fast growth in species around this time. What caused this rapid explosion in animal shapes? The two theories outlined are the changes in the earth’s climate and ocean oxygen levels we’ve mentioned, and competition and predation among the animals that had started getting more complex.

One of the hard-shelled organisms that flourished around this time was the trilobite. We’re being charitable when we describe these fossils as giant ocean cockroaches, and they are indeed distant relatives of both insects and lobsters. Like insects, trilobites were very good at finding food and reproducing – they were the dominant form of life on earth for millions of years. Then a mass extinction wiped them out. The last set of displays in Ocean Hall explains how this happened.

There have been 5 mass extinctions in the earth’s history, and scientists are debating whether we’re in the sixth right now. Extinction events can be caused by many things. In the case of the trilobites, evidence suggests that a volcanic eruption did them in, along with 95% of everything else alive - in the Permian-Triassic extinction of 250 million years ago. They can also come from space, as in the huge meteor that slammed into Mexico 65 million years ago, wiped out the dinosaurs, and marked the end of the Cretaceous period.

Your tour of Ocean Hall is finished after the displays on mass extinction events. If you’re doing a comprehensive tour of the museum, continue to the back of Ocean Hall and turn right and walk through the Mud Masons of Mali photography exhibit, and African Voices. If you’re touring the museum for half a day or less, head to the second floor’s exhibits now.

Other Lands at Smithsonian National Museum of Natural History

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