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!
Most snakes are relatively small, but there are a few species out there that are enormous. The biggest snake in the world is the reticulated python. Reticulated pythons, which are found in Asia, can reach lengths of close to thirty feet, and can weigh up to 350 pounds. Even newly hatched reticulated pythons are two feet long. These snakes are not venomous, but instead kill their prey by squeezing it to death, a process known as constriction.
It is very rare for these reticulated pythons to pose a danger to humans, though. Meanwhile, the most venomous snake in the world, the inland taipan, is far smaller—around 6 feet—but has enough venom in one bite to kill a hundred people. Inland taipans are shy, though, and rarely come into contact with people.
Photo by Bernard Dupont
Dolphins are some of the world’s most beloved animals– these intelligent, social sea mammals are popular in zoos and aquariums. Most of the dolphins in zoos are sleek, gray bottlenose dolphins, the most common members of the dolphin family. But there are dozens of species of dolphins– they come in all shapes and sizes. The world’s smallest dolphins are Maui dolphins, also known as popoto, which only reach five and half feet long and a 120 pounds. The world’s biggest dolphins are killer whales, which can reach over thirty feet in length. (Fun fact: all dolphins are technically whales.)
Dolphins don’t just come in gray, too. Dolphins can have a wide range of black and white markings, and some dolphins, like the ones in the Amazon River, are pink!
Photo by Jorge Andrade
If asked to explain what a snake is, a lot of people would probably say, “a reptile with no legs.” But that’s not quite right—while all snakes are legless reptiles, not all legless reptiles are snakes. Meet the legless lizards.
Legless lizards look a lot like snakes—many of them have scaly, snakelike skin, and they don’t have legs, so they move by slithering or burrowing in the earth. But there are some key differences that have shown scientists that legless lizards aren’t snakes—they’re part of the reptile family that includes four-legged lizards like geckos, but over time, they “lost” their legs to better suit their lifestyles. Their skeletons still show traces of these lost limbs—it’s a little like how human ancestors lost their tails, but we still have tailbones at the bottom of our spines. Some legless lizards have tiny little nubs where their ancestors had legs.
Some of the strangest legless lizards don’t even look that much like snakes—they look more like worms! Their scales are small and smooth, and they live underground, where they eat insects and larvae. But despite their appearance, these animals are still lizards!
Photo by Richard Avery
King cobras are some of the most well-known snakes in the world. They’re the longest venomous snakes in the world– adults are often up to 13 feet long, and the largest one on record was over 19 feet! Their venom is strong, but they are afraid of people and hunt rodents, lizards, and other snakes.
In addition to their venomous bite, king cobras are known for the beautiful appearance– they have “hoods” on their heads and sometimes have bright yellow chevron stripes. You can see one here at the Philadelphia Zoo— a female born in the wild in Indonesia in 2003. See how she’s flicking out her tongue? Snakes do that to “taste” tiny scent particles in the air to get a better sense of the world around them!