Category: Evolution

Who Eats the Largest Jellyfish in the World -- and Enjoys It?

2/13/2023

Stephen R. Swinburne

Lifelong Naturalist

Lion’s mane jellyfish can grow seven feet wide with tentacles reaching a length of 100 feet. That’s the same length as a blue whale! Their bodies are 98 percent seawater. They live in the cold, boreal waters of the Arctic, northern Atlantic and northern Pacific Oceans. Slowly pulsating ocean currents carry the big jellies great distances. The long trailing, stinging tentacles capture and tear apart their prey. Swimmers beware when currents sweep lion’s manes close to shore. Their stings cause red swollen welts, and severe body contact with a lion’s mane jellyfish may be deadly.

What animal can happily and safely slurp down a lion’s mane jellyfish as if it were a big bowl of Jello™? The leatherback sea turtle!

Adult leatherbacks are the largest reptiles on earth today, averaging seven feet long. As the planet’s biggest turtle, they range from the Arctic Circle south to Antarctica, and they swim, on average, more than 6,000 miles each year. And they love lion’s mane jellyfish. As a matter of fact, lion’s mane jellyfish make up almost their entire diet. How can a seven-foot long sea turtle consume a creature armored with a hundred feet of stinging tentacles?

Often referred to as Earth’s last dinosaur, leatherback sea turtles have lived on the planet for millions of years, surviving ice ages and major extinctions. For an animal to live that long on a diet of giant blobs of gelatinous saltwater, it better be very very good at tackling and consuming its delicious but dangerous meals of giant stinging jellyfish. And, it better have developed some cool adaptations over the ages. Here’s how they do it

First off, a sharp pointed lip acts like a hook so the turtle can snag the jellyfish and hang onto it.

Second, the turtle’s mouthful of backward-pointing spines prevents the jellyfish from escaping. A scientist once said to me, while looking into the mouth of a leatherback, “It’s the last thing a jellyfish will ever see!”

Once the leatherback has consumed dozens and dozens of jellyfish, there’s the problem of all that salt in its diet. Eating too much salt will cause dehydration. No problem for the leatherback! The turtle is perfectly adapted to rid its body of all that excess salt. Salt or lacrimal glands, located near their eyes, allow leatherbacks to secret saline tears—and then they cry them away.

So the largest marine reptile on earth evolved by getting better and better at eating the most unlikely diet, the largest jellyfish on earth.

Lion's mane jellyfish. Wikimedia Commons. Photo by Dan Hershman

A leatherback turtle excreting salt from its eyes. From Arkive.org, photo © Olivier Grunewald

Leatherback turtle.

This photo of Dr. Kimberly Stewart photographing a nesting leatherback gives you an idea of the size of the turtle. Photo by Claudia Lombard, U.S. Fish and Wildlife Service, Sandy Point National Wildlife Refuge, US Virgin Islands

Steve Swinburne has written a book on sea turtles. To see information about the book as well as a study guide and video and picture gallery, click here.

Steve Swinburne is a member of iNK's Authors on Call and is available for classroom programs through Field Trip Zoom, a terrific technology that requires only a computer, wifi, and a webcam. Click here to find out more.

MLA 8 Citation
Swinburne, Stephen R. "Who Eats the Largest Jellyfish in the World -- and Enjoys It?" Nonfiction, iNK Think Tank, 12 Oct. 2017, www.nonfictionminute.org/the-nonfiction-minute/who-eats-the-largest-jellyfish-in-the-world-and-enjoys-it.

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Amazing Maize

11/23/2022

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Dorothy Hinshaw Patent

Nature's Animal Ambassador

If I asked you what grain is the most harvested in the world, you’d probably answer either wheat or rice. But the answer is actually corn, more accurately called ‘maize.’ This nutritious crop that originated in Mexico feeds not only people but also animals around the world. We’re used to the wonderfully tender sweet corn harvested in late summer and early autumn, but most maize is actually field corn, more starchy than sweet and used as animal feed or to make cornmeal and flour.

For a long time, biologists puzzled about the origins of this important crop. There is no wild plant that looks anything like modern corn, which is actually a giant grass. The closest relative is a scrawny branching plant with hard dark seeds called teosinte. It seems a huge jump from teosinte to corn, yet geneticist George Beadle found in the 1930s that corn and teosinte have the same number of chromosomes and could be crossbred to produce hybrids. With the limited tools available at that time, Beadle deduced that only about five genes were involved in creating the differences between teosinte and corn.

Fast forward to modern times, when scientists can look directly at DNA and analyze every detail of its structure. We now know that Beadle came very close to the truth—about five regions in the DNA seem to control the major differences between teosinte and corn. For example, these two plants look so very different, yet just one single gene turns a branched plant into a single stalk, like a stalk of corn. Another single gene controls one of the most dramatic and certainly most important traits for farmers—the nature of the seeds and their stalk. In teosinte, each seed has a hard covering. Just one gene eliminates the hard covering and produces a stalk bearing exposed seeds, like an ear of corn.

Scientists now use maize as a perfect example of two major ways evolution happens. One way is through major sudden jumps, like the change from a branching plant to a single stalk. The other is the more gradual kind of change that has led to the thousands of different kinds of maize grown by farmers today. There are probably hundreds of varieties of sweet corn and thousands of varieties of field corn. Think about that the next time you bite into a nice crunchy taco made from a corn tortilla.

Here you can see the major differences between a teosinte plant and a corn plant. Credit:TeosinteCornUOR

Corn was a very important crop for homesteaders in the American West, used both to feed themselves as well as their animals. Read about it in Homesteading: Settling America's Heartland, revised and expanded edition, Mountain Press, 2013.

Dorothy Hinshaw Patent is a member of iNK's Authors on Call and is available for classroom programs through Field Trip Zoom, a terrific technology that requires only a computer, wifi, and a webcam. Click here to find out more.

MLA 8 Citation
Patent, Dorothy Hinshaw. "Amazing Maize." Nonfiction Minute, iNK Think Tank, 8
June 2018, www.nonfictionminute.org/the-nonfiction-minute/Amazing-Maize.

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Lonesome George: The Face of Extinction

1/4/2022

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Dorothy Hinshaw Patent
Nature’s Animal Ambassador

“Whatever happens to this single animal, let him always remind us that
the fate of all living things on Earth is in human hands.”

These words, inscribed on a panel by the enclosure where the last of his race, the Pinta Island tortoise called Lonesome George, are no longer needed. George died on June 24, 2012, at an undetermined age, but likely more than 100 years. Even so, his actual death is merely a symbol of extinction, since he was the only one of his kind left. Without a mate for George, this species was doomed.

Perhaps George’s death, however, will impress people with the power of our own species to doom or to save others. The thoughtless short-term thinking so common among humans ignores the long-term effects of our actions. During the 1800s, whalers, fur sealers, and other seafaring folks raided the Galapagos Islands for food. The giant land tortoises that populated the islands were perfect for long-term storage, as they could survive for a year or more on a ship without eating or drinking. Their diluted urine provided drinking water as well. The Pinta tortoise population was hit the hardest by this exploitation because Pinta is the farthest north of the islands and thus the last one visited when the sailors left for the open sea.

By 1959 the tortoises had just about disappeared from Pinta. Some fishermen released three goats there, knowing they would reproduce to make island meat once more available to ships. The goat population exploded, devastating the island vegetation and dooming any animals that depended on it for survival.

In 1979, a scientist studying snails came across George, who was soon brought to the Tortoise Center on nearby Santa Cruz Island for protection. But hopes of finding a mate for George and thus saving his species faded with the years, and Lonesome George became what he remains after his death, a symbol of careless exploitation by humans.

Now, after careful restoration of his remains, Lonesome George was on exhibit at the American Museum of Natural History in 2015, after which he was returned to Ecuador. The plaque overlooking his old corral now reads, “We promise to tell your story and to share your conservation message.”

In the early stages of the taxidermy process, multiple casts of Lonesome George’s extremities were taken for future reference. © AMNH/R. Mickens

This map shows the distribution of the various races of the Galapagos tortoise. The islands, collectively known as the Galapagos, are located along the Equator and are part of the nation of Ecuador. Image by Fallschirmjäger from Wikimedia

It is said that George’s head was used as an inspiration for the design of the movie character ET. Photo by Dorothy Patent

Lonesome George was recently on view in New York City's Museum’ of Natural History's 4th floor Astor Turret. © AMNH/R. Mickens

Some good news! Unlike the Pinta subspecies, conservationists have managed to help bring back the tortoises on the Galapagos island of Espanola from a low of only 16 to a population of more than 1,000 now living on their home island. Here, scientists are recording information about the tortoises in their native environment. Photo : Flickr: Sebastian Keynes via Christian Zeigler

Read how one endangered species got returned to its natural home and thrived in Dorothy's book, When the Wolves Returned: Restoring Nature's Balance in Yellowstone. She says " I loved writing this book, which describes the positive changes in the ecology of the park that are happening since the wolves came back--healthier willows, more beavers and small predators, more song birds, and more. Wolves have also returned to several western states around Yellowstone, including Montana, and their presence there is also helping restore the natural environment."
Dorothy Patent is a member of Authors on Call. You can bring her to your school via our Zoom Room. Here's a link to her program on wolves.

MLA 8 Citation
Patent, Dorothy Hinshaw. "Lonesome George: The Face of Extinction." Nonfiction Minute, iNK Think Tank, 27 Nov. 2017, www.nonfictionminute.org/ Lonesome-George-the-face-of-extinction.

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Dickens' A Christmas Carol: How a Short Story with a Big Message Helped the Poor

12/22/2021

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Andrea Warren
Giving Voice to Children in History

In 1843, thirty-one-year-old Charles Dickens had money problems. His wife was expecting their sixth child, he was in debt, and he supported a slew of needy relatives. He was known for long novels that were published in weekly installments, but because time was of the essence, he decided to write a short story (actually a long story by our standards, but short by his) that he could publish quickly.

          The British were enamored with the paranormal, so he decided it would be a ghost story. To increase interest, he included THREE ghosts. And to seal the deal, he added a bonus apparition that appeared at the stroke of midnight, dragging its chains from hell. That would get readers’ attention.

          He didn’t intend to simply entertain them. He was Charles Dickens, after all, and his writing was also meant to inspire. His family had once been poor, and his quest, as always, was to help the less fortunate. The tale he crafted happened at Christmas, a holiday that in England included charitable giving—the perfect setting for his message that charity must come from the heart, and that it’s never too late for redemption.

From his fertile imagination he conjured up Ebenezer Scrooge, “a squeezing, wrenching, grasping, clutching, covetous, old sinner!” whose refrain to anything distasteful was “Bah, Humbug!” Scrooge represented the self-serving upper classes, while his poorly paid clerk, Bob Cratchit, and his family, including sickly Tiny Tim, represent the deserving poor.

          Dickens sent Scrooge on a wild night’s journey, led by the ghosts of Christmases past, present, and future. Scrooge visited his childhood and learned why he’d become such a miserable miser, and he saw a grim future awaiting him if he didn’t change his ways. By sunrise Christmas morning he was a new man: his hard heart had melted and he became a good friend to the poor, beginning with the Cratchit family. He resolved to “honor Christmas in my heart, and try to keep it all the year.”

          To Dickens’ delight, his readers did the same. In example after example, A Christmas Carol inspired the upper classes to be more charitable to the lower classes. And because the book became a bestseller, it eased Dickens’ financial worries.

Dickens’ ghost story remains popular today, reminding us all that it’s never too late to do the right thing, and allowing us to proclaim with Tiny Tim, “God Bless Us, Every One!”

The title page of the original 1843 edition of "A Christmas Carol. In Prose. Being a Ghost Story of Christmas."

Scrooge and Marley -- a John Leech etching from the original edition of "A Christmas Carol:

The last of the spirits, a John Leech etching from the original edition of "The Christmas Carol"

Scrooge's third visitor -- a John Leech etching from the original edition of "A Christmas Carol

Scrooge and Bob Cratchit, a John Leech etching from the original edition of "The Christmas Carol"

Ignorance and want of the miser -- a particularly moving etching of children suffering. Drawn by John Leech for the original edition of "A Christmas Carol."

You can learn more about Charles Dickens and his stories in Andrea Warren’s book Charles Dickens and the Street Children of London and on her website.

Andrea Warren is a member of iNK's Authors on Call and is available for classroom programs through Field Trip Zoom, a terrific technology that requires only a computer, wifi, and a webcam. Click here to find out more.

MLA 8 Citation
Warren, Andrea. "Dickens' A Christmas Carol: How a Short Story with a Big Message Helped the Poor." Nonfiction Minute, iNK Think Tank, 12 Dec. 2017, www.nonfictionminute.org/Dickens-a-christmas-carol.

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Who Eats the Largest Jellyfish in the World -- and Enjoys It?

Amazing Maize

Lonesome George: The Face of Extinction

Dickens' A Christmas Carol: How a Short Story with a Big Message Helped the Poor

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