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7 Oddball Aquatic Mammals We Love

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Everyone knows all about dolphins and whales, and even dolphins that pretend to be whales (the orca! coughcough). But there are over 100 species of marine mammals in the world, and most of them have as much cool stuff going for them as any old Moby Dick.

1. Leopard seal (Hydrurga leptonyx)

You’ve probably heard of the leopard seal, well-known for being one of the world’s fiercest undersea predators; its name comes from its spotted coat, and from its huge mouth full of extremely sharp, terrifying teeth. Unlike other seals, which eat mostly fish, leopard seals feed on warm-blooded animals like seabirds, penguins and, yes, even other seals. Their diverse and surface-dwelling diet allows them to find plenty of food without needing to dive very deep.

2. Amazon River dolphin (Inia geoffrensis)

Known as the boto in Portuguese, the Amazon River dolphin is one of only five species of freshwater dolphin, four of which are severely endangered, and the last of which has gone extinct. The Amazon River Dolphin sometimes called the “pink dolphin,” though it is naturally white, taking on a pink, blue, or brownish hue depending on its diet and environment. The boto’s shape is different from sea-dwelling dolphins: it’s rostrum (snout) is extra long and thin, and instead of a pronounced dorsal fin, it has a long ridge along its back. Due to the low visibility in cloudy river waters, the boto also has tiny, poorly functioning eyes, and therefore relies almost entirely on echolocation to hunt its prey.

3. Dugong (Dugong dugon)

Along with its close relative the manatee, the dugong belongs to an animal order called Sirenia, derived from the belief that these arguably human-shaped creatures inspired tales of mermaids, who sang their siren song to ill-fated sailors. Less glamorously, the manatee and the dugong are informally known as “sea cows,” and use their large, rough lips to graze on sea grasses. In actuality, their closest relative among land animals is the elephant. The dugong is in a separate family than the better-known manatee, however; while the manatee has a completely round tail, the dugong’s tail is fluked, like that of a whale or a dolphin. And while manatees can live in freshwater, dugongs are strictly ocean-dwellers, making them the only marine mammals that subsist entirely on vegetation.

4. Cuvier’s beaked whale (Ziphius cavirostris)

For decades, scientists credited the sperm whale and elephant seal as performing the deepest and longest dives among air-breathing sea creatures. But recently, studies using digital tags have proven that the unassuming beaked whale leaves all other marine mammals in the proverbial dust. Cuvier’s beaked whale can dive up to 6,230 feet (1,900 meters) and for up to 85 minutes—about 2,00 more feet and 24 minutes beyond the sperm whale. It may not be the most beautiful or graceful of all cetaceans, but its thick, dense body is better suited to withstanding deep-sea pressure than to flitting about upon the waves.

5. Vaquita (Phocoena sinus)

People often use the terms “dolphin” and “porpoise” interchangeably, but the smaller, snub-nosed porpoises differ greatly from their more popular cousins in the Delphinidae family. Also known as the “Gulf of California porpoise,” the vaquita’s name means “little cow” in Spanish. It is endemic to the relatively shallow waters of the Gulf of California, inside Mexico’s Baja peninsula, where commercial fishing and changes in habitat make it one of the most endangered cetaceans on the planet. It’s also the smallest of all cetaceans, at about 4-5 ft. in length.

6. Long-finned pilot whale (Globicephala melas)

After the killer whale (orca) and the short-finned pilot whale, the long-finned pilot whale is the third-largest member of the dolphin family, Delphinidae (characterized primarily by their cone-shaped teeth). It also looks somewhat similar to the arctic’s beluga whale; both have bulbous “melon” heads, which help them echolocate. But unlike the long-finned pilot whale, the beluga is a true whale, most closely related to the narwhal (the one with the unicorn-looking horn).

In terms of social structure, however, the long-finned pilot whale is without rival. Known for being a gregarious species, with strong, maternally based social structures, they engage in a number of showy social behaviors like breaching, fluking, even swimming in formation, and are one of the species of cetacean most likely engage in mysterious mass strandings.

7. Polar bear (Ursus maritimus)

You read that right: Polar bears are scientifically categorized as marine mammals because they spend a large proportion of their time in the water, and rely on the ocean for survival. Other marine mammals in its order (Carnivora) are otters: the sea otter (Enhydra lutris) and the marine otter (Lontra feline). Which of these would you prefer to meet on a scuba dive?

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science
What Pop Culture Gets Wrong About Dissociative Identity Disorder
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From the characters in Fight Club to Dr. Jekyll and Mr. Hyde, popular culture is filled with "split" personalities. These dramatic figures might be entertaining, but they're rarely (if ever) scientifically accurate, SciShow Psych's Hank Green explains in the channel's latest video. Most representations contribute to a collective misunderstanding of dissociative identity disorder, or DID, which was once known as multiple personality disorder.

Experts often disagree about DID's diagnostic criteria, what causes it, and in some cases, whether it exists at all. Many, however, agree that people with DID don't have multiple figures living inside their heads, all clamoring to take over their body at a moment's notice. Those with DID do have fragmented personalities, which can cause lapses of memory, psychological distress, and impaired daily function, among other side effects.

Learn more about DID (and what the media gets wrong about mental illness) by watching the video below.

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History
Scientists Reveal Long-Hidden Text in Alexander Hamilton Letter
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Age, deterioration, and water damage are just a few of the reasons historians can be short on information that was once readily available on paper. Sometimes, it’s simply a case of missing pages. Other times, researchers can see “lost” text right under their noses.

One example: a letter written by Alexander Hamilton to his future wife, Elizabeth Schuyler, on September 6, 1780. On the surface, it looked very much like a rant about a Revolutionary War skirmish in Camden, South Carolina. But Hamilton scholars were excited by the 14 lines of writing in the first paragraph that had been crossed out. If they could be read, they might reveal some new dimension to one of the better-known Founding Fathers.

Using the practice of multispectral imaging—sometimes called hyperspectral imaging—conservationists at the Library of Congress were recently able to shine a new light on what someone had attempted to scrub out. In multispectral imaging, different wavelengths of light are “bounced” off the paper to reveal (or hide) different ink pigments. By examining a document through these different wavelengths, investigators can tune in to faded or obscured handwriting and make it visible to the naked eye.

A hyperspectral image of Alexander Hamilton's handwriting
Hyperspectral imaging of Hamilton's handwriting, from being obscured (top) to isolated and revealed (bottom).
Library of Congress

The text revealed a more emotional and romantic side to Hamilton, who had used the lines to woo Elizabeth. Technicians uncovered most of what he had written, with words in brackets still obscured and inferred:

Do you know my sensations when I see the
sweet characters from your hand? Yes you do,
by comparing [them] with your [own]
for my Betsey [loves] me and is [acquainted]
with all the joys of fondness. [Would] you
[exchange] them my dear for any other worthy
blessings? Is there any thing you would put
in competition[,] with one glowing [kiss] of
[unreadable], anticipate the delights we [unreadable]
in the unrestrained intercourses of wedded love,
and bet your heart joins mine in [fervent]
[wishes] to heaven that [all obstacles] and [interruptions]
May [be] speedily [removed].

Hamilton and Elizabeth Schuyler married on December 14, 1780. So why did Hamilton try and hide such romantic words during or after their courtship? He probably didn’t. Historians believe that his son, John Church Hamilton, crossed them out before publishing the letter as a part of a book of his father’s correspondence. He may have considered the passage a little too sexy for mass consumption.

[h/t Library of Congress]

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