Carnivora: The Incredible Cousins of Cats and Dogs, Part 2

A Newfoundland Pine Marten (Martes americana atrata). Photo by Bailey Parsons. Licensed by CC BY-SA 3.0.

A Newfoundland Pine Marten (Martes americana atrata). Photo by Bailey Parsons. Licensed by CC BY-SA 3.0.

Studying the branches of the animal family tree, each with numerous unique and related species, is nothing short of wondrous. In this four-part series, we’ll take a quick survey of the families in the Carnivora branch, which are the incredible cousins of cats and dogs!

The carnivans, as members of this branch are called, are some of the greatest predators on Earth, known for their sharp teeth, long whiskers, dense fur and hunting prowess. They’re essential players at the top of the food chain who stabilize populations of animals in local ecosystems. Thinning populations of weaker and less well-adapted animals through predation is one of the drivers of natural selection, which is a major factor in the process of evolution. The health of a species and its surrounding ecosystem is dependent in no small part on the vital role of predators.

In Part 1, we began our exploration with dog’s closest cousins, the Canidae family, and then learned more about the bear and red panda families. In Part 2 we’ll look at four more families on the dog-like Caniformia branch.

Carnivora Family Tree, Part 2. Illustration by Jeannette Chiappone.

Carnivora Family Tree, Part 2. Illustration by Jeannette Chiappone.

Let’s begin with a dogs’ cousins of the deep blue sea. When we think of mammals in the ocean, we may not immediately come up with any related to dogs. But think of barking, long whiskers and big brown eyes and I bet you guess some!

Semi-Aquatic Carnivans: Seals, sea lions and walruses!

Some of our dogs’ cousins are true seals, sea lions and walruses. These animals are from different families, but because their similarities are more apparent than their differences, we’ll study them together. As a group, true seals, sea lions and walruses are members of the Pinniped suborder. The Latin word “pinna” means wing, and if you think about it, fins and flippers are rather like wings of the sea. “Ped,” of course, is Latin for “foot.” While distantly related to dogs, Pinnipeds are more closely related to bears and Musteloids (who we will meet shortly). There are 33 Pinniped species in existence today.

Pinnipeds have four flippered limbs. Their substantial blubber layer makes their bodies wide and round but they narrow at the hips. Though Pinnipeds are not as sleek and fast as some sea mammals like dolphins, they have more flexible spines, giving them greater agility in the water. The smallest of the Pinnipeds, the freshwater Baikal seal, measures about 3 feet long and weighs around 100 pounds. The largest is the Southern elephant seal. This enormous seal can measure up to 16 feet long and weigh over 6,500 pounds, making it more than twice the size of a polar bear! The Southern elephant seal is the largest of all the animals in the Carnivora order.

Most Pinnipeds prefer colder waters where food is more plentiful. Only a few live in the subtropics and tropics. While considered semi-aquatic, because they come ashore to mate, give birth and escape becoming dinner for other predators, they spend the majority of their lives in the water. Their diet consists of fish and marine invertebrates, like crabs, clams and squid. Elephant and leopard seals also hunt larger prey, like penguins and other seals. Pinnipeds have specially adapted hemoglobin and myoglobin to store oxygen so they can hold their breath underwater for extended periods of time when hunting. Elephant seals have been timed to dive underwater for up to two hours!

Like all predators, seals’ and sea lions’ eyes are positioned at the front of their heads, giving them depth perception to better hunt their prey. In one of the rare exceptions, walruses’ eyes are on the sides of their heads. But walruses have no upper bone in their eye sockets and have specialized muscles around their eyes. This allows their eyes to protrude slightly and rotate forward to see frontally when needed. All the pinnipeds have sharp eyesight and hearing underwater but don’t see very well on land.

A pinniped’s whiskers are tremendously important for hunting. These long, sensitive vibrissae, as whiskers are called, detect subtle vibrations of other sea life swimming nearby in dark or murky waters. A walrus’s whiskers are so sensitive, they can even tell the shape of swimming objects from its vibrations. It’s almost as if they can see with their whiskers!

Harbor seal (Phoca vitulina). Notice her ear hole and the length of her flipper. Photo by Marcel Burkhard.

Harbor seal (Phoca vitulina). Notice her ear hole and the short length of her flipper. Photo by Marcel Burkhard. Licensed under CC BY-SA 2.0 DE

When it comes to telling these animals apart, walruses are easy. Those long tusks give them away! The differences between true seals and sea lions are easy to spot, too, once you know what to look for. True seals are much smaller than sea lions. Because their flippers are smaller, too, true seals swim by undulating their bodies to propel themselves forward. On land, they wiggle and shimmy on their bellies to move rather than using their flippers to push them along. One of the seals’ most distinguishing features is the lack of an outer ear, so they have only small holes on the sides of their heads where sound come in.

Some species of seals are highly social, gathering on beaches not to just mate and raise their young, but to keep each other company. Others species of seals are more solitary. They all, however, hunt alone. When it comes to communicating, true seals tend to be quiet but can make soft grunting noises if need be. You could say seals are a bit more introverted than other Pinnipeds.

Sea lions are a whole different kettle of fish, so to speak. Sea lions, unlike seals, are noisy and extroverted! When they bark, they really belt it out. They often gather on land for humongous get-togethers of as many of 1,500 to mate or just to hang out! When there are that many sea lions together, you can hear them from a great distance. They’re not particularly fazed by humans, either.

Sea lions are generally much larger in than true seals. Their flippers are longer and well-developed. To move around on land, they use their back flippers to rotate their hips and push, and their front flippers pull themselves forward. Unlike the earless true seals, sea lions have visible outer ear flaps.

In this video, you’ll be able watch and listen to a colony of sea lions who gather regularly at Pier 39 in San Francisco, exhibiting all manner of behaviors. They seem rather dog-like in many ways. Notice how long their flippers are, how they move about, and see if you can spot their little outer ear flaps and their long whiskers.

(Video by of Stig Nygaard. Licensed under CC BY 2.0.)

Let’s explore the walrus a bit, shall we? The walrus is the lone survivor of its family. It prefers to live in the coldest reaches of the Arctic circles along the Continental Shelves, rather than far offshore. Here, they hunt in the shallows of the sea floor by piercing sheets of ice with their tusks to make ports of entry into the water below.

Atlantic walrus (Odobenus rosmarus rosmarus), Foxe Basin, Canada. Photo by Ansgar Walk.

Atlantic walrus (Odobenus rosmarus rosmarus), Foxe Basin, Canada. Photo by Ansgar Walk. Licensed under CC BY-SA 3.0.

Because walruses live so close to shore, they’re easy for indigenous peoples to hunt. Their meat and blubber are essential for nutrition and fuel. Tusks and bones are fashioned into tools and adornments. The walrus hide is incredibly heavy, sturdy and warm. In fact, a walrus’s hide accounts for fully 20% of its weight. Walrus hide is so sturdy, it’s used by indigenous people to make boats and is used for walls and roofing of buildings.

While humans have hunted Pinnipeds throughout history, commercial hunting boomed in 18th and 19th centuries. Their meat, blubber and hides were in great demand. Walruses were hunted for the ivory of their tusks, as well. During that period, many species, including the Caribbean monk seal and the Japanese sea lion, were hunted to extinction. Others survived only in small pockets of their former expansive territories.

In the United States, the Marine Mammal Protection Act of 1972, made it illegal to hunt or even harass Pinnipeds, whales, dolphins and porpoises. These protections have helped to stabilize or increase some marine mammal populations, but not all. Even with these protections in place for over 40 years, all marine mammal populations have been depleted and many are still threatened or endangered.

If you ever come across a stranded marine mammal, remember it is illegal to bother it in any way. Stay far away! Instead, follow these steps to get it the help it needs.

There is yet another group of dog cousins who are denizens not only of the oceans, but the world’s rivers, and underground, too! Much like the Pinnipeds, some have been hunted to near extinction and are, thankfully, making a comeback.

Otters, weasels, badgers, mink and wolverines: the Mustelidae family

The largest and most diverse family of the Carnivora order is the Mustelidae, 57 species of otters, weasels, badgers, and wolverines. The first of these animals distinguished themselves in the fossil record 33 million years ago, making them one of the oldest branches the Carnivora order. Mustelidae members are characterized by long, slender, muscular bodies. They have short legs, round ears, and often have long tails. Sharp claws and teeth are their weapons for catching prey. While most of them hunt on land, some are exclusively marine predators.

North American River Otter (Lontra canadensis), The Scottish Sea Life Sanctuary. Photo by Allen Watkin.

North American River Otter (Lontra canadensis), at The Scottish Sea Life Sanctuary. Notice the webbing between his fingers. Photo by Allen Watkin. Licensed under CC BY 2.0.

Semi-aquatic otters, like Pinnipeds, do their hunting underwater. Their webbed fingers, flat tails and sleek bodies make them strong and efficient swimmers. Otters hunt underwater for fish and shell fish and some can hold their breath for nearly eight minutes!

Sea otters are the only ocean-going otter. Found along the coasts of the Pacific Ocean, from northern Japan, across the Bering Strait and down the coast to southern California, they prefer colder ocean water. Because they have no blubber layer, sea otters have the densest, warmest, and most water-repellant fur in the entire animal kingdom! Sadly, sea otters were hunted to near extinction in the last century because of the unique characteristics of their coats. The Marine Mammal Act and other international protections are helping them make a comeback.

River otters live along banks of fresh waters all over the world, except for Antarctica and Australia. The 12 species of river otters are each specialized to the region where they live, from tropics to tundra. The largest animal of this group is the giant river otter of the Amazon River region. They can measure up to 5 ½ feet long from head to tail and weigh up to 70 pounds. It’s a ferocious killer known locally as the “river wolf.” Because of poaching, toxic run-off into rivers and habitat loss, the giant otter and many other otters are endangered species.

Least Weasel (Mustela nivalis), British Wildlife Centre, Surrey, England. Photo by Kevin Law.

Least Weasel (Mustela nivalis) is the world’s smallest carnivore. The male is about 8 inches long and weighs around 3 ounces. British Wildlife Centre, Surrey, England. Photo by Kevin Law. Licensed under CC BY 2.0.

The terrestrial members of the Mustelidae family are significantly smaller than otters, while their diversity is much greater. This enormous group includes (from smallest to largest): weasels, stoats, polecats, ferrets, minks, martens, badgers and wolverines.  These animals closely resemble each other with the exception of badgers and wolverines, who are broader and heftier than the others. Because of their size, badgers and wolverines don’t scamper about like the rest of the family but lumber along more slowly.

Mink, ermine and sable, like sea otters, are known for their beautiful, luxurious coats. When a stoat’s fur turns white, as it does in the winter, it’s called an ermine. Sables are a species of marten, a tree dwelling member of the family. Needless to say, all of these species have been hunted for their coats for centuries. The sea mink is now extinct and the European mink is endangered. Fortunately, the American mink and ermine populations are doing well. In the 1940s, Russians began commercially raising sables, thus ensuring their survival.

The smaller members of this family have a particularly high metabolic rate because the large surface area of their long bodies gives off lots of heat and they don’t store much fat. The result is, these little guys eat about half their weight in prey every day to just to survive! They even hunt when they’re not hungry, just to stash snacks in a holes for later. That’s a whole lot of mice and rats. The upside to their long, slender bodies is that it allows them to shimmy down the narrowest of burrows to find a meal.

Surprisingly, it’s the smaller species of this group, though lithe and elegant, who are its most ferocious hunters. Some kill prey as much as ten times larger than themselves. A tiny weasel can easily subdue a big rabbit. Springing suddenly to bite into the larger animal’s neck, they hang on tightly during the ensuing struggle, biting deeper and deeper until its prey dies. These little predators hunt mice, rats, voles, snakes, frogs and rabbits.

The hefty and much slower badger uses its long claws to dig for insects to eat but will hunt small mammals, too. The largest of this family, the wolverine, which resembles a small bear, subsists largely on carrion left over from the catch of wolves and other big predators. In a pinch, they’ll hunt anything from a gopher to a moose! But they prefer to let others do the hard work.

The smelliest fellows: Skunks and stink badgers

Dogs, as many of you dogs lovers know, identify each other through the scent of their anal glands. Anal scent glands are common in nearly all animals of the Carnivora order and many other mammals, too. To one degree or another, these glands are a powerful means of communication among animals. Skunks and stink badgers, however, have taken these anal scent glands to a whole other level!

Patagonian hog-nosed skunk (Conepatus humboldtii), Eastern Patagonia. Photo by Payayita.

Patagonian hog-nosed skunk (Conepatus humboldtii), Eastern Patagonia. Photo by Payayita. Licensed under CC BY 2.0.

Though relatively small, skunks and stink badgers can leave a big impression! Their highly developed anal scent glands produce simple sulfur and hydrogen compounds called thiols, which are horrifically nasty smelling! Using the muscles surrounding their scent glands, skunks can spray a stream of thiols as far as 20 feet with alarming accuracy! The scent is so horrible it can ward off nearly any animal who threatens it, including bears. But their scent glands only hold 5 or 6 squirts of thiols. Once they run out of smelly spray, it can take up to 10 days to replenish the supply. So skunks and stink badgers only spray in the most dire of situations when they’re really scared. It’s used only as a defense, never on offense, though it’s offensive enough.

Skunks and stink badgers are quite considerate when letting others know they’re about to launch a stink bomb. First, they’ll stomp the ground a bit, squealing and hissing. They may even lunge at their perceived threat to try to scare them off. If you ever see any of these behaviors, step away from that skunk! Avoid any sudden movements! Walk backwards slowly. If they turn and raise their tail, it’s too late! The blast is on its way!

There are 12 species of these stinky dog-cousins. Up until recently, skunks were believed to be a type of weasel, and skink badgers another kind of badger. DNA analysis has found, however, that these smelly fellows are in a family all of their own, the Mephitidae. Luckily for most of the world, skunks only live in the Western Hemisphere, and stink badgers only in Indonesia and the Philippines. Their distinctive black and white stripes make them easy to spot.

Because skunks and stink badgers are slow and plodding, their prey largely on insects they can dig out of the ground, or small snakes and mice, and ground-dwelling bird’s eggs. They’re don’t object to nibbling on a bit of vegetation, either.

On another branch of the Carnivora family tree are animals also known for their distinctive markings. These bandit-masked cousins of dogs are among the most adaptable and successful in the order.

Masked marauders with banded tails: Raccoons

Raccoons originally lived only on the North American continent until they were introduced to Europe and Japan by humans. These mischievous masked bandits of the Carnivora order thrive just about wherever they go. One of the reasons for their success is that they enjoy so many different types of food.

Three raccoons in a tree, Toronto, Canada. Photo by Gary J. Wood. Licenced by CC BY-SA 2.0.

Three raccoons in a tree, Toronto, Canada. Photo by Gary J. Wood. Licensed under CC BY-SA 2.0.

Unlike their closest relatives, the red pandas of the Ailuridae family who eat mostly bamboo shoots and leaves, raccoons’ diet is fully omnivorous. A bit surprisingly, they only hunt small mammals like mice in a pinch. Instead, raccoons feast on insects, nuts, berries, bird’s eggs, small amphibians and fish. In fact, their fishing skills could be related to one of their unique behaviors.

Raccoons are known for their unusual “food washing” habit. They’ll hold bits of food in their dextrous little hands, dip the morsels in water and seem to rub it clean. But what they’re actually doing is exploring their food with their fingers. You see, the raccoon’s most finely-tuned sense is their sense of touch. Two-thirds of their cerebral cortex is devoted to tactile sensory information, more than any other animal. Because they have a thick outer layer of skin on their fingers and toes, that sensitivity is diminished. But when wet, the thick layer softens and raccoons regains their tactile sensitivity. Dipping food in water and then feeling it is how raccoons know what they’re eating. And because of this, raccoons in the wild live near water and seem to prefer fishing to other means of finding food. Nevertheless, they’re not too fussy about this. Raccoons manage to make the best of things wherever they are, and they find urban environments to be especially appealing.

As many of us know, raccoons are successful urban dwellers. Raccoons have high tolerance to disturbance, are natural explorers, and don’t mind trying new things. Traffic noise, pavement, humans chasing them off picnic tables, and having to find new homes when a dog discovers where they live are no problem to raccoons. Their unflappability, along with being happy omnivores, are the characteristics most important for wildlife to adapt to city life. As pesky as they may be at times, remember, they’re keeping insect and reptile populations under control, even if they do raid your garbage bin from time to time. Raccoon populations, unlike so many other families of the Caniformia suborder, are healthy and thriving because they’re so adaptable.

Have you noticed something about the fur markings of members of the Caniformia suborder? With the exceptions of raccoons, red and giant pandas, skunks and badgers, few species of this suborder have distinguishing markings. Now consider the members of the cat-like Feliformia suborder. Stripes, spots and swirls are practically guaranteed with the cats! But that difference between the dog-like and cat-like families is just skimming the surface.

Let’s explore the cousins of cats in depth in Part 3 of this series.





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