The sloth is an animal that uses its claws to hang from branches.
Credit: © Michael Fogden, Bruce Coleman, Inc.

Slow down and wait a minute! Today is International Sloth Day, a day to slow our speed and appreciate the world’s slowest mammal. While many species evolve to eat more, sloths have done the opposite! They evolved in a way that allows them to eat less and survive just by slowing down.

A sloth is a mammal that has a slow and peculiar way of moving. Sloths spend nearly all of their time in rain forest trees in Central and South America, where they travel upside down, hanging from branches with their hooklike claws. Hanging upside down requires almost no energy for a sloth. They can fall asleep in this position and may even stay suspended in the trees for some time after they die. There are two main groups of sloths. One is two-toed and the other is three-toed.

All sloths have small heads, and their noses are blunt. They have peglike teeth. Two-toed sloths also have large sharp teeth at the front of the mouth. Both measure 15 to 30 inches (38 to 76 centimeters) long and weigh 5 to 23 pounds (2.3 to 10.5 kilograms). Their long, coarse fur grows in the opposite direction as that of other mammals, from the stomach towards the back. This allows rain water to easily drain off the body as the sloth hangs. The fur ranges from grayish to brownish in color, which makes them hard to see among the branches.

Sloths turn green in the rainy season from algae that grows in their fur. This helps the sloth blend into the rain forest and protects it from large birds of prey, such as the harpy eagle, and big cats. Sloth fur also provides a home to a variety of invertebrates (animals without backbones) — some of which are found nowhere else on earth. A single sloth can host more than 100 moths and other insects within its fur.

Sloths get little energy from their diet, feeding mostly on leaves. Two-toed sloths may also eat fruits and flowers. They need relatively little food and have a lower rate of metabolism than do other mammals of similar size. Metabolism is the process by which living things turn food into energy. In order to save energy, sloths do not regulate their body temperature like other mammals. They have a lower body temperature than most mammals, which varies with the environmental conditions.

A sloth can take up to 30 days to digest a single leaf. As a result, they have a constantly full stomach. Sloths climb down to the forest floor to defecate (eliminate wastes) about once a week. They can lose up to a third of their body weight in one sitting. Sloths are surprisingly good swimmers. During the rainy season they can swim about three times faster than they can move on the ground.

Although commonly grouped together, the two types of sloths are actually very different animals with very different lifestyles. Two-toed sloths are slightly larger, more active, have a broader diet, and are generally faster-moving than the three-toed sloth. They have brown hair with a long, pinkish, piglike snout. Three-toed sloths have gray hair, a white face and a dark mask around the eyes. Two-toed sloths are primarily active at night, while three-toed sloths are active throughout the day and night. Although almost all mammals possess seven cervical (neck) vertebrae as standard, sloths are one of the few mammals that do not. Two-toed sloths retain only five to seven cervical vertebrae, while three-toed sloths have eight or nine. This unusual trait enables three-toed sloths to turn their head through 270 degrees. This allows them to look for predators and to see the world right side up, while hanging upside down. Sloths can live up to about 30 years.

August 14, 2019

Tomorrow, August 15, is the 500th anniversary of the founding of Panama City, the capital and largest city of the Central American country of Panama. The city, which lies at the Pacific Ocean end of the Panama Canal, is the oldest European settlement on the Pacific coast of the Americas. Panama City has been a crossroads of world trade and travel since its founding in 1519, and it has grown into a modern international banking, cultural, and tourist center.

Panama City was founded 500 years ago, on Aug. 15, 1519. The city overlooks the Bay of Panama, part of the Pacific Ocean. Credit: © AFP/Getty Images

Panama City’s 500th birthday celebrations, titled Panamá 500, began in May with an urban art project known as the Panama Mural Fest. The project decorated the walls of each of the city’s 26 districts with paintings depicting the area’s diverse culture and history. In July and August, retrospectives on Panamanian cinema and photography took place, along with a variety of academic, cultural, dance, gastronomic, and musical activities. Tomorrow, August 15, the birthday party peaks with a boisterous parade and an elaborate fireworks show.

People stroll the Avenida Central in Panama City. The city is celebrating its 500th birthday in 2019. Credit: © JJM Stock Photography/Panama/Alamy Images

Pedrarías Dávila, a Spanish adventurer also called Pedro Arias de Ávila, founded Panama City in 1519, just six years after Vasco Núñez de Balboa became the first European to see the Pacific coast of the New World in 1513. At the time, Pedrarías was governor of an area that included parts of present day Panama. (A feud between Balboa and Pedrarías resulted in Balboa’s execution in 1519.) The newly constructed port, which became Panama’s capital in 1524, served ships that were exploring and exploiting the Pacific coasts of present day Ecuador, Peru, and Chile.

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Panama City is home to a number of cultural attractions, including the Museum of Religious Art and the Museum of Contemporary Art. Credit: WORLD BOOK map

In 1671, the English pirate Henry Morgan led a force of 1,400 men against Panama City, and much of it was destroyed. (The ruins of the original city, known as Panamá Viejo [Old Panama], are a popular tourist attraction.) In 1673, Panama City was rebuilt about 5 miles (8 kilometers) away, and buildings from this time remain in the city’s Casco Viejo (Old Quarter). Casco Viejo was named a World Heritage Site in 1997, and Panamá Viejo was added in 2003. Such sites are places of unique cultural or natural importance, as designated by the United Nations Educational, Scientific and Cultural Organization (UNESCO).

Panama City prospered as Panama was increasingly used as a shortcut between the Atlantic and Pacific oceans (an alternative to traveling by ship around the tip of South America). In the mid-1800′s, a railroad was built across Panama to carry the many people traveling west during the California gold rush. Construction of the Panama Canal, which followed the railway route and opened in 1914, gave Panama City increased importance and made it a center for world trade.

Today, treelined boulevards cross downtown Panama City. This area contains a broad promenade along the seafront. Interesting downtown buildings include the Palace of Justice, the Presidential Palace, and the historic Museo del Canal (Canal Museum). The nearby ATLAPA (Atlantic and Pacific) Convention Center, which can hold more than 10,000 people, overlooks the ocean. The Panama Metro, Central America’s first urban rail system, opened in Panama City in 2014. The Biomuseo, designed by the American architect Frank Gehry, has exhibits about the history of the Isthmus of Panama and the region’s influence on world biodiversity. Outside the city, national parks protect the tropical rain forests, which are home to a wide variety of plants and animals.