Deer are what biologists call “even-toed ungulates.” That means that they’re hoofed animals that bear weight equally between their third and fourth toes. Even-toed ungulates include deer, elk, and moose, as well as some more unusual creatures. Goats, cows, camels, giraffes, and pigs, are all even-toed ungulates too. Whales are also technically part of this group, since whales descended from hoofed creatures that lived on land.
Other hoofed animals are less closely related to deer. These animals are “odd-toed ungulates,” and they descend from animals that put their weight on their third toe. Horses, peccaries, and rhinoceroses are all examples of odd-toed ungulates. Who’d have thought that whales are more closely related to deer than horses are?
Photo by Bureau of Land Management
The Navajo Zoo in Window Rock, Arizona, is the country’s only Native American-owned-and-operated zoo. They’re home to over fifty species of animals native to the Navajo Nation, a reservation area covering over 17,500,000 acres in Arizona, New Mexico, and Utah. The largest deer species found at the Navajo Zoo is the elk. Elk can grow up to 700 pounds and are found within forested areas. On the Navajo Zoo’s website, you can learn more about elk and about the relationship between different animals and Navajo culture.
Photo by MONGO
In 2017, scientists discovered a new species of great ape: the Tapanuli orangutan. Previously believed to be a kind of Sumatran orangutan, genetic testing revealed DNA different enough to make the Tapanuli orangutan its own species. These apes are only found in the southern part of Sumatra, an island in Indonesia. They live in trees to avoid Sumatran tigers, and their diet includes caterpillars and pine cones.
Tapanuli orangutans aren’t just the newest species of great ape—they’re also the rarest. Hunting and destruction of their forest homes have left them critically endangered. There are only 800 left in the world. One way we can help Tapanuli orangutans is avoiding products made with palm oil, since palm oil plantations are a major cause of deforestation in Indonesia. When you buy peanut butter, look for products without palm oil—it could help an orangutan!
Photo by Tim Laman
Triceratops and Eotriceratops were some of the biggest ceratopsians, or horned dinosaurs. They could reach lengths close to 30 feet and weighed up to 20,000 pounds– more than two hippos. But while the ceratopsian family included big dinosaurs, some of their earlier relatives were tiny. Aquilops americanus was less than two feet long and weighed about three pounds. It probably walked on two legs like another early ceratopsian family, the Psittacosaurids. Some fossils of Psittacosaurids have been found with preserved bristles on their tails, a little like a porcupine.
While the word “ceratopsian” means “horned face,” not all of these dinosaurs had big horns like Triceratops. Many of the smaller earlier members of the family lacked horns, but just about all of them thick beaks that helped them snip plants to eat.
Illustration by Nobu Tamaru
Baby harp seals get a lot of attention– with their big eyes and fluffy white coats, we humans find them pretty adorable. But they don’t get all that much attention from their parents. Newborn harp seals weigh about 24 pounds, and in the twelve days after their birth, they drink their mothers’ milk, reaching a weight of 80 pounds in just a couple weeks. But after two weeks of nursing, mother harp seals leave their babies to fend for themselves, and the mothers move on to have more young. Their white fur provides camouflage against the ice, and the blubber the baby seals developed drinking their mothers’ milk keep them warm and provides them with nutrients until they’re old enough to hunt for themselves, when they’re about a month old. It’s a tough childhood, but the seals that make it go on to live thirty years or more!
Photo by Lysogeny
Humans’ closest cousins are chimpanzees and bonobos. These smaller members of the Great Apes are intelligent, social animals. They’ve been spotted using tools to hunt, and they are emotionally complex. Chimpanzees and bonobos have been observed to mourn their dead, play make-believe, and take care of other animals—for instance, sometimes they feed turtles. All these activities are signs of great emotional intelligence.
There are some key differences between chimpanzees and bonobos, though. Chimps are more aggressive and live in male-run societies, whereas in bonobo groups, the females are in charge, and there’s generally less in-fighting.
Photo by Psych USD
Sea lions might share part of their name with a big cat, but they’re actually more closely related to dogs! Sea lions are part of the big group of meat-eating animals called Carnivora– the carnivores. Carnivores are split into two sub-groups: the ones that are more closely related to cats, called feliforms, and the ones that are more closely related to dogs, called caniforms. Sea lions, along with seals and walruses, are caniforms. Like dogs, wolves, and bears, they tend to have long snouts and claws that don’t retract.
Sea lions do have some things in common with lions, though. They’re good hunters, and they’re very social animals that live in large groups. When they’re in a group together on land, they’re called a colony, and in the water, they’re called a raft. Breeding groups of sea lions are called rookeries.
Photo by Reywas92
Scientists need to be able to tell the individual animals they’re studying apart, and the zookeepers at the Seneca Park Zoo have a new idea about how to do that. Scientists often tell animals apart by tagging them, but that can be stressful for animals. So, zookeepers are finding new ways. They’ve been analyzing the whisker patterns of sea lions to see if they can tell the animals apart by looking at their whiskers instead of by tagging them. You can read more about their efforts here!
Photo by Kelli O’Brien
When we think of dolphins, we often picture sleek gray animals that are about ten feet long. However, the biggest dolphins in the world are more than twice that size– and they might look different that you’d expect. The world’s largest dolphins are actually orcas, also known as killer whales.
Orcas reach lengths of up to 26 feet and can weigh up to six thousand pounds– more than a rhinoceros. Orcas are apex predators, meaning that they are hunters that live at the top of the food chain. They eat fish, seals, and even other dolphins!
Photo by Christopher Michel
The biggest dinosaurs in the world belong to the sauropod group– the giant, four-legged, long-necked plant-eaters. It’s hard to tell exactly which species was the biggest, since it’s rare to find complete dinosaur skeletons. Scientists have to use the pieces they do find and use them to estimate what the entire body size would be.
A recently-discovered dinosaur just might be the biggest known to science– a titanosaur called Patagotitan mayorum. This dinosaur reached lengths of over 120 feet long and likely weighed 76 tons, making it quite possibly the largest animal ever to walk on land. However, there are even bigger animals in the ocean– the blue whales alive today weigh 300,000 pounds!
Illustration by Levi Bernardo
Scientists at zoos work to protect all kinds of animals, from ones found on the other side of the world to ones right in our backyards. At the Lincoln Park Zoo in Chicago, scientists study wild Eastern massasauga rattlesnakes to help conserve the species. These snakes live in wetlands and grasslands around the central United States, and every spring, Lincoln Park Zoo scientists head a few hours out of the city to count the rattlesnakes. The scientists place harmless tracking devices in the snakes, similar to microchips for dogs and cats, and measure the snakes to get a better sense of what makes for a healthy snake habitat. In a recent trip, they found fifty snakes in just a single day!