There are 15 Families in the Order Carnivora. It’s difficult to designate one single family as “most successful” for the simple fact that “success” in this case means whether they exist or not. The ability to exist long-term is determined by “adaptability”. The planet has been in constant flux since the beginning, for a myriad of reasons. Those animals that have been able to adapt, are still with us and therefore are successful. Successful = Adaptable. There were plenty of families that have been “unsuccessful”, resulting in extinction. Otherwise, if they still exist… they are successful. This would put the majority of families in a tie, since they have healthy populations that currently exist. One cannot say that Sea Lions (Phocidae) are more successful than Skunks (Mephitidae), since there is a preponderance of both; as is the case with most of the families. Populations are at their maximum level that can be supported by the ecosystem. Over-populations of species have a way of self-regulating themselves by purging themselves by starvation over excess populations; thereby maintaining a balance.
However… it might be easier to identify which families are currently least successful, meaning they are in the most trouble, and in danger of dying off completely.
The Order of Carnivora is separated into two Sub-Orders: Feliformia and Caniformia… literally, Cat-like & Dog-like. Beyond that, each Sub-Order is divided into individual Families, shown here. And within each are individual Genus & Species.
Suborder Feliformia (Cat-like Carnivorans)
- Family Prinonodontidae (Asiatic Linsangs)
- (Cats – 40 species)
- Family Viverroideae (Civets – 35 species)
- Family Hyaenidae (Hyenas and Aardworlf – 4 species)
- Family Eupleridae (Malagasy Carnivores – 8 species)
- Family Herpestidae (Mongooses – 33 species)
Suborder Caniformia (Dog-like Carnivorans)
- (Dogs – 37 species)
- (Bears – 8 species)
- (Red Panda)
- Family Mephitidae (Skunks – 10 species)
- (Ferrets, Weasels, Martens, Badgers, Wolverines, Minks, and Otters – 55 species)
- Family Procyonidae (Raccoons – 19 species)
- Family Odobenidae (Walrus)
- Family Otariidae (Sea lions, Eared Seals and Fur Seals – 14 species)
- (True Seals – 19 species)
As I said, most families are wildly successful, and have been for tens of millions of years. All the families contain species that are threatened or endangered, but generally not enough to endanger the entire family. Tigers, for instance, are very endangered. But there are 39 other species in the Family Felidae, some of which are extremely healthy. There are some 600 million domestic cats (Felis catus) in the world. This puts Felidae as a whole, on firm footing.
Having said that:
* Family Ailuridae (Red Panda): only has one species left in the entire family. The rest are extinct. The surviving Red Panda are listed as Threatened. There are less than 10,000 left, and that comprises the entire Family. Deforestation and poaching may be the cause for eventual extinction of the Ailuridae Family. These are man-made causes, but nevertheless, they will not be able to adapt as other successful species have, to changes in their environment. This should qualify them as one of the least successful families.
*Family Eupleridae (Fossas & Falanoucs): There are eight species in this family. They are nearly all threatened, by virtue of living in Madagascar. Again, hunting and loss of habitat is to blame. Madagascar does not put environmental protection high on its list of priorities as most of the country is very poor. Although, there are other poor countries that do manage to care for their wildlife. It is just not part of the culture here. The animals can’t adapt, as they are too specialized, and therefore must be classified as one of the least successful families.
(Look at that looooong beautiful tail on that Fossa! Amazing!)
So there, by the definition that success = adaptability, are the least successful existing families in the order of Carnivora. All the other families are tied for first place and are doing fine at the family level, despite individual species from each family who are not adaptable enough to rank high on the success level.
However… if you want to define “successful” as that family which contains the largest number of different thriving species, then the winner would be Family Mustelidae(Ferrets, Weasels, Martens, Badgers, Wolverines, Minks, and Otters), which contains at least 55 different species ; more than any other. This would suggest that the “design” characteristics common to these particular similar animals has led to the highest number of currently surviving and thriving species. Obviously, with their combination of traits, they have been able to adapt, despite everything man and nature throws at them.