Carnivore

The term carnivore is thought by many to refer to any meat-eating organism, but in the life sciences it is applied to a certain family of mammals (Carnivora) that have specially shaped teeth and live by hunting. Carnivores are animals that obtain most of their nutrition from eating other animals, and their name comes from a combination of Latin words that literally mean "flesh devourers." Carnivores are always at the top levels of every food chain.

CHARACTERISTICS OF CARNIVORES

There are eight families of terrestrial (land-dwelling) carnivores and three families of aquatic (water-based) carnivores. A family is a classification term that includes one or more genera (singular, genus), and a genus contains one or more species. What best defines a carnivore are its teeth, although most have powerful jaws and a keen sense of smell as well. Since it lives primarily by hunting, catching, killing, and eating its prey, a carnivore has teeth that are specially shaped for all of those demanding tasks, especially for gripping and cutting. These specialized teeth come in sets that have particular functions. The canine teeth are the longest. It is with these curved weapons that a carnivore both grabs and punctures its prey. The canine teeth are best used for holding prey since they can pierce it deeply. The chisel-shaped incisors are next to the canines and are at the center of the jaw. With these, the carnivore bites into food and slices it up. Carnivores also have a unique set of teeth called carnassials that form the first set of molars. These sharp teeth have a pointed edge, and the top slides along the bottom like scissors. Carnassials are used to slice through tough flesh and gristle (cartilage especially present in meat) and to crack open bones. Since they are near the hinge of the jaw, they can close with great force. After a carnivore has caught, killed, and eaten its prey, its specialized digestive system takes over. Since its main diet of meat is easier to digest than the tough material of plants (plant cells are surrounded by a tough wall of cellulose), a carnivore's intestines are much shorter than those of a herbivore (plant-eating organisms) like a horse or cow. A carnivore also a much simpler stomach.

As a predatory animal or one that lives by killing and eating other animals, a carnivore has other distinguishing characteristics that enable it to capture and subdue its prey. One of these is its brain, which is often fairly large and complex. Such a brain means that a carnivore's behavior can be somewhat flexible and that it can rear its young. Some carnivores are particularly social creatures and hunt in packs. This allows them to overwhelm creatures that an individual could not catch on its own. Most carnivores are either speedy runners or very quick and nimble. For example, the cheetah is the fastest land animal on Earth, able to reach 75 miles-per-hour (120.68 kilometers-per-hour) in short bursts. Others have endurance like wild African dogs that can run for 3 miles (4.83 kilometers) at a speed of 35 miles-per-hour (56.32 kilometers-per-hour). Because carnivores must find and catch their food, they are often very active and aggressive animals. However, since they do not have to eat continuously the way herbivores do, they are able to spend more time relaxing in between meals.

LAND-DWELLING AND SEA-DWELLING CARNIVORES

There are about 240 species of carnivore belonging to two suborders or major groups: Fissipedia, or land-dwelling carnivores, and Pinnipedia, or sea-dwelling carnivores. Some biologists, however, consider Pinnipedia to be a separate order like Carnivora. There are three families that make up Pinnipedia and eight families in Fissipedia, each of which has its own specialties and characteristics.

Mustelidae Family. One of the largest members of the Fissipedia group is the Mustelidae family consisting of small carnivores like skunks, badgers, weasels, and ferrets. These sleek animals can burrow into hard-to-reach places and catch their prey. Some of these carnivores depend on foul-smelling spray for defense. They are aggressive and often take on animals that are larger than they are.

Procyonidae Family. The Procyonidae family includes raccoons and the tropical coati, which are less carnivorous and more omnivorous creatures (eating both plants and animals). Tropical coati have teeth that reflect their diet since their carnassials are more like grinding teeth. They are usually slow runners but excellent climbers and often live in groups.

Canidae Family. The Canidae family is especially diverse, consisting of wolves, foxes, and dogs. Very adaptable animals with a keen sense of smell, they are good at running and often hunt in packs. The dog was probably the first animal to be domesticated (tamed) by humans. They live in groups, take care of their young, and are very territorial (defending where they live).

Felidae Family. The Felidae family is made up of some of the most efficient carnivores: the cats. Divided into two main groups called simply big cats and small cats, they can range in size from a tiny 2-pound (.91-kilograms) animal to one more than 750 pounds (340.50 kilograms). The big cats include lions, tigers, jaguars, leopards, and cheetahs. Among the small cats are bobcats, lynxes, pumas, and domestic cats. An interesting difference between the two groups is that big cats can roar but not purr, while small cats can purr but not roar. Despite this oddity, all cats are especially good hunters, possessing retractable claws that are kept razorsharp and allow them to pad silently while stalking prey. They have large, pointed canine teeth and forepaws used to swipe at and claw their prey. Finally, most cats are solitary hunters.

Hyaenidae Family. One of the more unusual groups are the members of the Hyaenidae family. Hyenas are skilled hunters who work together in packs and are one of the few carnivores that will regularly eat carrion (an already-dead animal). Hyenas are fiercely wild-looking, with heavy bodies and front legs that are longer than the rear ones, giving them a crouching or lurching-forward look. Their skulls are strong and their powerful teeth can easily crush bone, their favorite food.

Viverridae Family. The Viverridae family is represented by civets and genets which live in tropical areas. They resemble weasels and have long

noses and short legs. Besides meat, they will also eat insects as well as fruit and eggs, and possess scent glands that produce musk, long-sought for its use in perfumes and lotions.

Herpestidae Family. The Herpestidae family is made of many species of mongoose and is an offshoot from the Viverridae family. Some species are solitary while others are very social and live in groups. Viverridae eat insects as well as meat.

Ursidae Family. Probably the most awe-inspiring and terrifying of the carnivores are the members of the Ursidae family, better known as bears. Including the polar bear, black bear, brown bear, or grizzly bear, all have large bodies and short, powerful limbs. While their sense of smell is much better than their hearing or sight, bears can walk or run upright on the soles of their feet. They are fiercely aggressive when provoked and have few natural enemies. Despite their appearance, bears are mostly omnivorous, and spend more time foraging for insects and berries than catching and eating prey. The exception are polar bears, which are mainly flesh-eaters and are such strong swimmers they have been known to pursue they favorite food (seals) as far as 40 miles (64.36 kilometers) from land.

Phocidae, Otariidae, and Odobenidae Families. The three families of the aquatic Pinnipedia suborder are made up of the Phocidae family (sea lions, fur seals, and earless seals), Otariidae family (eared seals), and the Odobenidae family (walrus). Called pinnipeds, all of these marine animals reproduce on land despite the fact that they spend most of their time in the water. All hunt underwater and have adapted to this environment, having nostrils that can close, limbs that are modified fins, and an insulating layer of fur or blubber to reduce the loss of body heat in cold water. Their hearing is especially keen and they can dive to great depths.

All meat eaters do not belong to the Carnivora order, as there are birds (eagles and hawks), reptiles (snakes and alligators), fish (sharks and barracuda), and even plants (Venus's flytrap) that regularly live on a diet of meat. Although many humans regularly eat meat, they are instead classified as omnivores because of their varied diet.

Carnivora (cohort Ferungulata, superorder Ferae) An order that comprises the modern carnivorous placental mammals and their immediate ancestors. It used to be divided into two suborders, the Fissipedia (mainly land-dwelling) and Pinnipedia (seals, sea lions, walrus), but a more modern classification is into Caniformia (dog-like) and Feliformia (cat-like), with the ‘pinnipeds’ belonging to the former. The carnivores are descended from a single stock of the probably insectivorous, placental mammals of the early Cretaceous, the change being reflected in their dentition. Strong incisors for biting, and canines for piercing, were retained from the insectivorous forms, but in general carnivores acquired modified cheek teeth (carnassials) specialized for shearing. These subsequently became reduced in those carnivores which adopted a herbivorous diet. Hoofs have rarely developed, as claws are used for seizing prey, and digits are never greatly elongated (and, apart from the pollex and hallux, they are not reduced). The first true carnivores were the weasel-like Miacidae of the Palaeocene, which had diverged by the end of the Eocene to give the Canidae (dogs) and Mustelidae (weasels and their allies) as one branch and the Viverridae (Old World civets) and Felidae (cats) as another. According to some authors, the Mustelidae later branched again to give the Phocidae (seals); and the Canidae diversified widely to produce such forms as the Amphicyonidae (‘dog-bears’), Otariidae (sea lions), Procyonidae (raccoons and pandas), and, ultimately, Ursidae (bears); but molecular studies seem to indicate that the Phocidae and Otariidae are descended from a single ancestor which was related to the mustelid-ursid-procyonid stem. Finally, the Hyaenidae (hyenas) emerged in the late Miocene from viverrid stock; this is the youngest of the carnivore families.

Carnivore

In the literal sense, a carnivore is any flesh-eating organism . However, in the ecological usage of the word, carnivores kill animals before eating them (that is, they are predators), as opposed to feeding on animals that are already dead (the latter are called scavengers or detritivores).

Trophic ecology deals with the feeding and nutritional relationships within ecosystems, and this field has developed some specialized terminology. Carnivores, for example, are heterotrophs, which means that they must ingest other organisms to obtain energy and nutrition . (In contrast, autotrophs such as green plants can fix their own energy and synthesize biochemicals utilizing diffuse sources such as sunlight and simple inorganic molecules.) Animals that feed on plants are herbivores (or primary consumers), while animals that eat herbivores are known as primary carnivores (or secondary consumers), and carnivores that feed upon other

carnivores are tertiary consumers. It is rare for an ecosystem to sustain carnivores of an order higher than tertiary. This is due to the pyramid-shaped structure of productivity in ecological food webs, which itself is caused by thermodynamic inefficiencies of energy transfer between levels. Therefore, the productivity of green plants is always much larger than that of herbivores, while carnivores sustain even less productivity. As a result of their trophic structure, ecosystems cannot sustain predators that feed upon, for example, lions, wolves, or killer whales.

Another consequence of the pyramidal structure of ecological webs is the tendency of top carnivores to bioconcentrate especially large residues of fat-soluble, persistent chemicals such as the chlorinated hydrocarbons , DDT, PCBs, and dioxins. This happens because organisms in successive levels of the trophic web absorb most of the chlorinated hydrocarbons that they ingest, storing these chemicals in fatty tissues. Consequently, top carnivores further concentrate the pre-concentrated residues of organisms lower in the ecological web. Therefore, the largest residues of these chemicals occur in peregrine falcons , polar bears , and seals , and these top predators have a disproportionate risk of being poisoned.

Almost all carnivores are animals. However, a few carnivores are specialized species of plants that trap, kill, and digest small animals, and then absorb some of their nutrients . Examples of these so-called carnivorous plants include Venus flytrap, sundews, and pitcher plants.

See also Food chain/web; Herbivore; Heterotroph; Omnivore; Predator; Scavenger; Trophic levels.

Carnivore

A carnivore is an organism that eats animals. Two ecological groups of carnivores are predators that hunt their prey in order to eat it and scavengers that feed on dead animals.

Carnivores are heterotrophs, which means that they obtain energy and nutrients from other organisms. (In contrast, autotrophs such as green plants can fix their own energy and synthesize biochemicals utilizing inorganic sources such as sunlight and simple inorganic molecules.)

In a simple ecological food chain, animals that feed on plants are herbivores or primary consumers. Animals that eat herbivores are primary carnivores or secondary consumers. Carnivores that feed on other carnivores are tertiary consumers. Because energy is lost at each level of the food chain, most ecosystems have few large carnivores. In addition, some toxins found in the environment are not easily metabolized and tend to become concentrated in top carnivores as they are passed along a food chain. This process, called biomagnification is especially significant in large residues of fat-soluble, persistent chemicals such as the chlorinated hydrocarbons, DDT, PCBs, and dioxins. Extremely high concentrations these chemicals have been found in peregrine falcons, polar bears, and seals.

Almost all carnivores are animals. However, a few carnivores are specialized species of plants that trap, kill, and ingest small animals, and then absorb some of their nutrients. Examples of carnivorous plants include Venus flytrap, sundews, and pitcher plants.

See also Food chain/web; Herbivore; Heterotroph; Omnivore; Predator; Scavenger; Trophic levels.

Carnivora (cohort Ferungulata, super-order Ferae) An order that comprises the modern carnivorous placental mammals and their immediate ancestors. It used to be divided into two suborders, the Fissipedia (mainly land-dwelling) and Pinnipedia (seals, sea lions, walrus), but a more modern classification is into Caniformia (dog-like) and Feliformia (cat-like), with the ‘pinnipeds’ belonging to the former. The carnivores are descended from a single stock of the probably insectivorous, placental mammals of the early Cretaceous, the change being reflected in their dentition. Strong incisors for biting, and canines for piercing, were retained from the insectivorous forms, but in general carnivores acquired modified cheek teeth (carnassials) specialized for shearing. These subsequently became reduced in those carnivores which adopted a herbivorous diet. Hoofs have rarely developed, as claws are used for seizing prey, and digits are never greatly elongated (and, apart from the pollex and hallux, they are not reduced). The first true carnivores were the weasel-like Miacidae of the Palaeocene, which had diverged by the end of the Eocene to give the Canidae (dogs) and Mustelidae (weasels and their allies) as one branch and the Viverridae (Old World civets) and Felidae (cats) as another. According to some authors, the Mustelidae later branched again to give the Phocidae (seals); and the Canidae diversified widely to produce such forms as the Amphicyonidae (‘dog-bears’), Otariidae (sea lions), Procyonidae (raccoons and pandas), and, ultimately, Ursidae (bears); but molecular studies seem to indicate that the Phocidae and Otariidae are descended from a single ancestor which was related to the mustelid-ursid-procyonid stem. Finally, the Hyaenidae (hyenas) emerged in the late Miocene from viverrid stock; this is the youngest of the carnivore families.