Cobras play a strong role in any fantasy set in an exotic locale. The image of the dangerous serpent in thrall to a skilled musician almost always comes to mind when discussing cobras. The king cobra (Ophiophagus hannah) is the world's largest venomous snake and its bite has the capability of killing an elephant. The term 'cobra' is a generic term that can refer to many different species of venomous snakes, some from different genera, although true cobras are found in the genus Naja. If the definition of cobra is restricted to only that genus, the king cobra cannot be considered a true cobra.
Scientific & Common Names
Kingdom - Animalia
Phylum - Chordata
Class - Reptilia
Order - Squamata
Suborder - Serpentes
Family – Elapidae
Genus - Naja, Ophiophagus, Hemachatus
Common names - Cobra
There are around 270 species of cobra and their close relatives, kraits, coral snakes, mambas, adders, and taipans, but only a few dozen of those are in the Naja genus. Because there are so many species, they also have a variety of living environments. They can be burrowers (Paranaja multifasciata), arboreal (Black tree cobra - Pseudohaje nigra), semi-aquatic (Banded water cobra - Naja annulata), or dwell in plains and jungles (Indian cobra - Naja naja). Almost all cobras have the classic 'hood', the skin around their head and neck that can be stretched out to make them appear larger and more threatening.
Cobras lay eggs and some will create nests while other species will not, but many will protect the eggs during the three month incubation period. The mother leaves the nest immediately as the eggs begin to hatch and the young must fend for themselves. The hatchlings have venom of the same potency as adults and they are more nervous and prone to strike.
In general, cobras are not overly aggressive and will only strike when threatened. Unlike other snakes with a defensive display, such as rattlesnakes, cobras almost always display their hood before striking. However, due to the amount and toxicity of their venom, any bite is a serious issue. Their main prey items are reptiles (including other snakes, even of their own species), birds, and small mammals. They can become prey to other animals, most famously mongoose and large birds of prey.
There is more scientific debate concerning the evolution of venom than of snakes themselves. There are different types - hemotoxins, cytotoxins, and nerotoxins - and many different potencies. There is not even a single delivery system as the giant spitting cobra (Naja ashei) demonstrates, though it only spits in defense and still bites its prey. It is not known if venom evolved independently or if all snakes had a shared venomous ancestor from 100 million years ago. Venom is a complex combination of proteins and enzymes and many snakes use a blend of different types of venom.
King cobras are protected in India, but they are not internationally listed as endangered, only vulnerable. Although there is some evidence of decline, there are currently no cobra species listed as endangered.
There is some indication that various species of cobras have been released in southern Florida but, unlike the established Burmese python, there is no evidence yet of breeding populations.
Snakes: The Evolution of Mystery in Nature (Director's Circle Book of the Associates of the University of California)by Harry W. Greene
Cobras (World of Reptiles) by Sophie Lockwood
Popular Science - Evolution’s Most Effective Killer: Snake Venom
United States Geological Survey