December 26, 2016

Some people are brave enough not to scream when they find a creepy, finger-sized house centipede in their home. However, the sight of a forearm-sized Amazonian giant centipede skittering along the wall would cause nearly anyone to shriek and run away. Growing to about 1 foot (30 centimeters) long, the Amazonian giant centipede is the largest living centipede on Earth. Its segmented body is coppery red to dark maroon in color, and its 42 to 46 legs are red or yellow. It lives in the Amazon rain forest and other tropical forests of South America. Like other centipedes, its body does not retain water very well, so it prefers to spend time in humid, moist places, such as leaf litter, rotten logs, and damp caves.

Amazonian giant centipede (Scolopendra gigantea). Credit: Katka Nemčoková (licensed under CC BY-SA 3.0)

Most centipedes feed on insects and spiders, but the Amazonian giant centipede is so large that it also eats such vertebrates (animals with backbones) as lizards, snakes, mice, birds, and frogs. The massive centipede uses its front legs as sharp claws to catch prey. Once an animal is caught, the centipede delivers a terrible bite with its mandibles (jaw structures) and injects a dose of powerful venom that paralyzes its victim, allowing the creepy hunter to enjoy a fresh meal. The Amazonian giant centipede is even known to hunt bats in their roosting caves. With its back legs anchored onto the cave ceiling, the centipede dangles itself upside-down and waits in the darkness to catch a bat in mid-flight.

For people, a bite from an Amazonian giant centipede is extremely painful and can cause swelling, fever, weakness, and vomiting. Luckily, humans are too big for even the biggest centipedes to eat, so Amazonian giant centipedes do not attack humans unless threatened. In fact, many farmers and gardeners in tropical South America are happy to have these many-legged monsters around, because they help to keep pest populations under control.

August 29, 2016

A stream might seem like a great place to get away from biting and stinging bugs in tropical climates. In parts of Southeast Asia, however, it might not be a good idea after all. In June, scientists there announced they had discovered a new species of giant centipede. Unlike other centipedes, however, this species lurks in dark waters and is a powerful swimmer. The scientists published their description in the scientific journal ZooKeys.

Swimming centipede (Scolopendra cataracta)
Credit: Warut Siriwut, Gregory D. Edgecombe, Chirasak Sutcharit, Piyoros Tongkerd, Somsak Panha (licensed under CC BY 3.0)

Centipedes are a group of animals with long bodies and many pairs of legs. Although they vaguely resemble six-legged insects, they are not closely related to them. The narrow bodies of centipedes are divided into many segments (sections) that lie behind each other. Each section has two legs. Some centipedes have only 15 pairs of legs, while others have more than 180 pairs. A centipede’s head includes two antennae (jointed feelers) and a pair of jaws. The first pair of legs behind the head are modified into fangs. Centipedes use these fangs for defense or capturing prey, but not for walking. The fangs are called poison claws because a gland in the head fills them with poison.

The new species of swimming centipede is named Scolopendra cataracta. It is nocturnal (active at night). When it enters the water, it swims with powerful undulations (wriggles) of its body, similar to the way an eel swims. It is found in rivers in the Southeast Asian countries of Thailand and Laos and grows up to 8 inches (20 centimeters) long. Poison from the swimming centipede and its relatives is not fatal to humans, but stings can cause terrible pain in the affected limb for days. The poison is more than adequate to subdue small aquatic invertebrates, which the scientists assume are the swimming centipede’s usual prey. More research must be done, however, to study this animal and learn about its ecology.

The scientists who discovered the swimming centipede think that the nighttime waters of of tropical rivers and lakes hold many more surprises. Such habitats have long been observed during daylight hours, and many of the species that are active during the day have been catalogued. Finding creepy-crawly critters at night, however, can be a bit trickier. Who knows what other new species scientists may find while peering into moonlit waters?