A boomslang (Dispholidus typus) is a relatively small, venomous colubrid snake native to sub-Saharan Africa. It is currently the only species in its genus, although several species and subspecies have been described in the past. Its name means "tree snake" in Afrikaans and Dutch ("boom" meaning tree, and "slang" meaning snake). In Afrikaans the name is . The snake is thought to be closely related to members of the genera Thelotornis, Thrasops, Rhamnophis, and Xyelodontophis, with which it forms the tribe Dispholidini.
Boomslangs are oviparous
. The eggs have a relatively long incubation period. Hatchlings are greyish with blue speckles. They attain their adult coloration after several years.
Behavior and diet
Boomslangs are diurnal
, largely arboreal
, and are oviparous
. Their diet
and other arboreal lizards
, and occasionally small mammals
from nesting birds, all of which they swallow whole. During cool weather they will hibernate
for moderate periods, often curling up inside the enclosed nests
of birds such as weavers.
Many members of the family Colubridae that are considered venomous are essentially harmless to humans, because they either have small venom glands, relatively weak venom, or an inefficient system for delivery of venom. However, the boomslang is a notable exception in that it has a highly potent venom, which it delivers through large fangs that are located in the rear of the jaw. The venom of the boomslang is primarily a haemotoxin
. It disables the blood clotting process and the victim may well die as a result of internal and external bleeding. Other signs and symptoms include: headache, nausea
, sleepiness and mental disorders. Because the venom is slow to act, symptoms may not be manifest until many hours after the bite. On the one hand, this provides time for procuring the serum
, while on the other hand it may lead victims to underestimate the seriousness of the bite. (Snakes of any species can on occasion fail to inject venom when they bite and after a few hours without ill-effect the victim may fall into the error of supposing that the injury was not serious).
An adult boomslang has 4–8 milligrams of venom. 5 milligrams are enough to kill a man.
In 1957, well-known herpetologist Karl Schmidt died after being bitten by a boomslang. D.S. Chapman states that between 1919 and 1962 there were eight serious human envenomations by boomslangs, two of which were fatal. The South African Vaccine Producers (formerly South African Institute of Medical Research) manufactures a monovalent antivenom for use in boomslang envenomations.
The boomslang is a timid snake and bites generally occur only when people attempt to handle, catch or kill the animal. The above data suggest that boomslangs are unlikely to be a significant source of human fatalities throughout their distribution range, so they can hardly be regarded as a threat to mankind.