The blue-ringed octopus, shown in this photograph, is both beautiful and dangerous. The octopus has a venomous bite that has killed several people.
© Richard Merritt, FRPS/Getty Images

Australia is famous for its unique culture, metropolitan cities, and unusual wildlife, among other things. Each week, this seasonal feature will spotlight one of Australia’s many wonders.

What has eight arms and a venomous bite? The blue-ringed octopus. The blue-ringed octopus is a kind of sea animal found in the tropical and subtropical waters of Sri Lanka, the Philippines, Australia, and south Japan. It is recognizable by its psychedelic spots that are ringed with bright blue. The bodies of most blue-ringed octopuses measure about 11/2 to 21/2 inches (4 to 6 centimeters) in diameter. They measure up to about 4 inches (10 centimeters) with their tentacles.

Blue-ringed octopuses like to hide under rocks or in crevices during the day, coming out during the night. Though they inhabit depths as far down as 160 feet (50 meters), you don’t want to get caught near their parrotlike beaks. Sometimes, they bite people. The venom from their salivary glands then enters the wound. Several people have died from bites by these animals. The bite is often painless. A small spot of blood on the skin when the animal is removed may be the only clue that a bite has been sustained. The first effect of the venom is a rapidly developing numbness. Victims often stop breathing, requiring mouth-to-mouth resuscitation. Treatment is the same as for snakebite. No specific antidote is available.

The blue-ringed octopuses belong to the genus Hapalochlaena.

July 4, 2016

The black mamba shows its ominous black smile. Credit: © NickEvansKZN, Shutterstock

Widely regarded as one of the world’s deadliest snakes, the monstrous reputation of the black mamba (Dendroaspis polylepis) is well deserved. A deep-seated fear of this snake is found throughout Africa, where local folktales attribute almost magical powers to it. The fear stems from the mamba’s aggressive disposition, lightning-quick speed, and lethal venom—and, because it lives in densely populated regions, the snake kills hundreds of people every year. Among locals in South Africa, a bite from this sleek and beautiful snake is referred to as “the kiss of death.” Once bitten, victims are said to take only two steps before they die.

The black mamba is not black, as the name implies, but actually gray, brown, or olive in color. The name comes from the dark black lining of the snake’s mouth which it displays with a wide gape when threatened. If the warning is not heeded, the aggressive mamba may strike. An adult mamba can reach 8 feet (2.5 meters) in length. Its body is long and slender, with smooth scales and a narrow head. The black mamba is also one of the fastest snakes in the world. Many tales describe its speed and aggressive nature—so aggressive that it is often said to chase after people. These serpents move faster than many people can run—about 12 miles per hour (19 kilometers per hour) over short distances—another reason for their fearsome reputation.

According to legend, the black mamba will bite its own tail to make a hoop and roll down a hill to gain speed. As the mamba gets to the bottom, it unwinds and flings itself like a high-speed missile towards its victim. Another popular myth claims that the mamba can balance its entire body on the tip of its tail to strike at a person’s face. One folktale claims that the black mamba is so intelligent that it actually plans its attacks on people. The snake is said to lurk at roadsides, where it waits to coil around the axle of an automobile. It then strikes the first foot out of the vehicle.

As with most legends, the reality of the black mamba is much less sensational. The snake is an active diurnal (daytime) predator, so it is often seen. That does not mean it is waiting to spring a trap, however. It hunts warm-blooded prey, but the black mamba does not pursue humans. In fact, the snake will usually flee human contact unless it is cornered. If that happens, the mamba will aggressively defend itself by rearing up, lifting two-thirds of its body off the ground, and striking with such force that it seems to shoot through the air.

There is no debating the black mamba’s lethal potential. It can strike repeatedly—up to 12 times in rapid succession. Short fangs at the front of the snake’s mouth efficiently inject its extremely potent venom. The neurotoxic venom, which is poisonous to nerve cells, immediately disrupts nerve transmissions in the body, rapidly affecting heart rate, vision, and breathing. Just two drops of black mamba venom can kill a human. If a person is bitten, death follows within 20 minutes unless antivenin (snakebite serum) is administered promptly. This perishable serum, however, is not widely available in the black mamba’s habitat in rural southern and eastern Africa.