Dogs Cats Bears and other Mammals an Overview of Carnivora

Not all Carnivores are meat eaters and not all meat eaters are classified as Carnivora.  Kingdom Animalia, Phylum Chordata, Subphylum Vertebrata, Class Mammalia, Order Carnivora consists of a group of animals that share a common history and ancestors.  Early in the evolution of the Mammalia, some ancestral species developed teeth and claws suitable for a meat-eating lifestyle.  Over time this species evolved outwards into the many living species that we recognise today as carnivores. 

The Order can be further divided into two suborders.  The Fissipedia, which means claw-footed, contains the families  Felidae (cats), Canidae (dogs and wolves), Ursidae (bears) and Mustelidae (weasels, stoats and ferrets),  Procyonidae (racoons), Viverridae (mongooses) and Hyaenidae (hyenas).  The Pinnipedia or flipper-footed suborder contains the eared seals, the true seals and the walruses.  Some people put the Pinnipedia in their own order so we will concentrate here on the Fissiped families and save the specialised pinnipeds for a separate article.

Members of the order Carnivora share important characteristics, even if they have secondarily left the meat-eating mode behind, such as the pandas.  They are placental mammals so they have fur, nurse their young and incubate their young via a placenta in the safety of a womb.  There is an equivalent family of carnivorous marsupials, the Dasyuridae.  These meat-eaters are examples of carnivores that are not Carnivora because they have pouches and the similarities with the placental Carnivores are due to convergent evolution.

The Fissipeds can be subdivided into the  cat-like carnivores (Feliformia) and the dog-like carnivores (Caniformia) which evolved their separate ways in the Eocene era some 50 million years ago.  From the Caniform ancestors came the various dogs, wolves and foxes plus the pinnipeds.  We will look at these caniform families first.   The family Canidae is diverse, containing some 35 species in ten genera.  They have a world-wide distribution with the exception of isolated islands such as New Zealand and Madagascar where the   domestic dog has been introduced.  Canids include wolves, coyotes, jackals, foes, african wild dogs, the dhole, the maned wolf, the domestic dog and three other doggy types: the bush dog of South America, dingos in Australia and the raccoon dog of Eastern Asia. 

Canids are adapted for hunting in open country so they tend to be lithe with bushy tails and long legs for running.  They have digitigrade four-toed feet and the claws are not retractable.  The smallest is the Fennec fox which weighs less than a kilogram and the largest is the Grey Wolf which can reach weights of 80 kilos.  Although they evolved in grasslands they have radiated out to inhabit many different ecosystems.

The bear family, Ursidae, is much smaller, with seven species in five genera.  They are found mostly in the northern hemisphere but range from the Arctic tundra to tropical rainforests.  The smallest is the asiatic sun bear while the largest bears are the Grizzly or brown bear and the polar bear.  The American and Asiatic Black bears are smaller than the brown bear but live similar life styles.  The other bears are the sloth bear and the spectacled bear.

The raccoon family, Procyonidae, is restricted to North and South America, except for the two panda species in central Asia.  There are 17 species in 8 genera.  Besides the pandas, there are six species of raccoons, three species of coatis, two species of South American Olingos, two other unusual South American species, the ringtail and the cacomistle, and lastly the kinkajou.  They are usually subdivided into the herbivorous pandas and all the rest, which are omnivorous.  Most procyonids are small with long bodies and  tails, and have five toes on each foot, with non-retractable claws.  The pandas also have a sixth digit that acts as an opposable thumb,D which further separates them from their omnivorous cousins.  Most procyonids are nocturnal and all are forest dwellers although the common raccoon has also adapted to farms and suburbs.

The weasel family, Mustelidae, is quite large and diverse with almost 70 species recognbised in 26 genera.  They are smaller in general than the canids, have long bodies and tails like the raccoons and also have five toes with non-retractable claws.  As well as weasels, stoats, ferrets, mink and ermine, the family contains the skunks, polecats, wolverine, otters, badgers and the honey badger. distribution is world-wide except for Australia and they shouldn’t be in New Zealand either except for a well intentioned but disastrous introduction policy by early settlers.  Weasels and the like are seldom seen but fairly common.  They are nervous animals, always on the move and deadly hunters.  Otters have taken up an aquatic lifestyle, with the sea otter being the most adapted for life in the water.

The Mongooses, or Viverridae, are restricted to Southern Europe, sub-saharan Africa and Southern Asia but within that region are quite diverse, with 66 known species in 37 genera.  They are found in forests, savannahs and deserts.  Viverrids differ a lot in body form and diet but most are omnivorous.  They can have four or five toes on each foot but all have non-retractable claws.  Like the weasels and raccoons, they are lively, intelligent little predators. 

The last family of carnivores with unretractable claws is the Hyaenidae,or hyenas, with four species in three genera. They are pack hunters and scavengers found through much of Africa except the Sahara, and the Middle East.

This leaves the other major group of Carnivores, the Felidae or cat family.  All cats have retractible claws.  They are divided into 35 species in four genera and are found world-wide except for Australia and New Zealand, until the unfortunate introduction of the domestic cat.  Cats are the ultimate carnivores and the most specialised, feeding almost entirely on other vertebrates.   Their teeth and claws make them formidable predators, especially the big cats:  lions, tigers, leopards, jaguars and cheetahs.  There are also 28 species of smaller cats including the ocelot, puma, bobcat and lynx.  One big difference between the big cats and the small is that big cats cannot purr but only roar, while small cats can purr.  Most cats hunt at night or dusk and dawn and have large eyes with both binocular and color vision.  They see much better than humans at night and can adapt quickly to darkness.  They also have excellent senses of hearing and smell plus touch with their sensitive whiskers.  Most cat species are forest dwellers and good climbers.  Most are also solitary and secretive.  The exception is the diurnal, social and anything-but-secretive lion.  But when you are that big, why not flaunt it?

For some 20 million years, carnivores ruled supreme at the top of the terrestrial world’s food chains.  All that has changed with the rise of the carnivorous primate.  Many carnivores are now endangered and may disappear from the wild.  That is a crime against nature and we should be doing everything in our power to see that it does not happen.

References:  MacDonald, D.  1989.  The Encyclopedia of Mammals  Unwin Hyman, Sydney 

McKay, G.  2002The little Guide to Mammals  Fog City Press