Here is our last monster of the series.

September 14, 2015

Naked mole-rat (© Frans Lanting Studio/Alamy Images)

Moles and rats are not creatures known for their physical beauty. Yet both are relative cuties compared with their namesake, the naked mole-rat. As the name suggests, this burrowing rodent of East Africa is nearly hairless and covered in wrinkled, pink skin. Beady eyes, a piglike snout, and huge buck teeth complete the naked-mole rat’s signature look.

You might pity the naked mole-rat its hideous appearance. But looks mean little in the darkness of the mole-rat’s underground lair. The naked mole-rat spends its entire life underground, living with up to 300 of its relatives in a burrow consisting of many tunnels and rooms.

Perhaps the strangest thing about this little monster is its social structure. A naked mole-rat colony works more like an ant colony than a typical mammal family. Each naked mole-rat colony has one breeding female—the queen—and one to three breeding males. The rest of the mole-rats do not breed. They spend their time caring for the queen’s young, hunting for food, fighting off invaders, and otherwise contributing to the well-being of the colony.

The naked mole-rat queen is larger than the other members of the colony and can bear more than 100 pups in a year. She is no doting matriarch, either. She harasses (bullies) nonbreeding females and males to prevent them from breeding. If the queen dies, another female develops into a queen, grows larger, and begins to breed.

Naked mole-rats are unusual in many other ways. For example, their body temperature varies with the surrounding temperature more than that of any other mammal. Also, naked mole-rats can tolerate stagnant air with high levels of carbon dioxide.

Here is another monster for your collection.

September 11, 2015

Marabou (Credit: © Ekaterina Brusnika, Shutterstock)

The beauty, sweet songs, and other charms of birds have inspired poets, painters, and composers throughout the ages. However, few of these artists were likely inspired by the marabou, one of the largest members of the stork family. These birds, found throughout Africa, are not heavy on looks or charm. In fact, many people consider the marabou to be the ugliest of all birds. A Ugandan proverb states that “When God made all of the birds of the world, he took the leftover parts and made the marabou.”

The marabou stands up to 5 feet (1.5 meters) tall on long legs. The wings and upper body are slate-gray or black, and the underparts are white. The long head and neck of these birds is featherless and covered with mottled skin. Both male and female marabous have a long pouch of reddish skin hanging down from the neck. A marabou can inflate this pouch with air, which may help it attract other marabous as mates. The birds smell as bad as they look. This is partially because they are usually covered in gore from feasting on carcasses (dead bodies). Marabous also habitually spray their feces (solid bodily wastes) onto their own legs. Scientists do not know if this revolting cologne is used to raise their attractiveness to potential mates.

Marabous are often called “The undertaker bird” because with their naked head and dark feathers, they resemble a slim, bald undertaker in dark clothes laboring over a fresh corpse as they feed on large carrion (dead and decaying animal flesh) that makes up their diet. Marabous are often found, sometimes in great numbers, lurking around garbage dumps, slaughter houses, fish-cleaning stations, and any place where carcasses can be found. Other carrion-eaters, such as vultures, usually make way for the large, ill-tempered marabous which are known to occasionally attack other birds.

In spite of their gruesome reputation, marabous play a valuable role in the ecosystem. As scavengers, the birds help reduce diseases and clean up the environment by eating carcasses. In the past, the birds were economically important as well. Manufacturers once used the soft white underfeathers of marabous to make scarves and to trim hats and gowns.

Another animal in the Monster Week series…

September 10, 2015

Bobbit worm (Credit: © Ethan Daniels, SeaPics)

In the dark of night, the monster’s head peeks out from the surface, exposing a tiny fraction of its long, snakelike body. Five antennae detect tiny disturbances from its prey. Its sharp jaws are open incredibly wide, ready to slam shut like scissors. When its prey approaches, the creature lunges with lightning speed. If it doesn’t succeed in slicing its prey in half, the beast drags its pitiful victim into its underground lair, where it injects it with toxins (poisons) and digestive acids. Although this sounds like a scene out of a science fiction horror movie, it is actually a description of the hunting practices of the bobbit worm, found in oceans across the world.

The segmented bobbit worm belongs to the genus Eunice. Its body is made up of dozens of ringlike segments. Each segment has two pairs of stumpy leglike appendages that the worm uses to move through the sand where it makes its home. The bobbit worm is one of the largest worms, growing over 12 feet (3 meters) long. There are some reports of individuals reaching over twice that length, however. Some bobbit worms have a bright, iridescent shine.

The worm lives at the bottom of shallow, tropical oceans throughout the world, for example in coral reefs. It buries itself in sand and mud and puts out mucus (a slimy substance, such as snot) from its body to form underground tubes. From these tubes, it hunts as an ambush predator, sticking its head out of the sand and lunging at animals that stray too near. Though well known for this hunting behavior, bobbit worms are actually omnivores, eating just about anything that drifts near their lairs.

Occasionally, bobbit worms find their way into public and private aquariums, where they terrorize their tankmates and anger aquarium keepers. It is thought that young worms are accidentally brought into tanks along with sand and rock harvested from warm ocean waters. In aquariums, small worms go unnoticed, scavenging or feeding on invertebrates (animals without backbones). Eventually, however, bobbit worms grow large enough to attack fish. They typically destroy traps designed to capture marine worms. Often, aquarium keepers have to take apart their entire tank setup in order to capture them.

The bobbit worm is not very well studied. The genus Eunice contains hundreds of species, and there are likely many more to be discovered. Many parts of the worm’s life cycle and habits remain a mystery. Who can blame scientists for not studying such a scary creature?

Another entry for World Book’s Monster Week is scary to look at but well adapted to its environment.

September 9, 2015

Goblin shark. Credit: © David Shen, SeaPics

The goblin shark looks more like a monstrous underwater alien than the sleek, streamlined ocean predator that comes to mind when you think of sharks. This bizarre deep-water shark gets its name from its terrifying appearance. But despite its ugliness, the goblin shark’s unusual body structure is perfectly suited for survival in the dark ocean depths.

The goblin shark has a pinkish-grey body, 12 to 18 feet (3.5 to 5.5 meters) long, with soft skin and flabby muscles. This shark has a long, flattened snout that overhangs its mouth, giving it a blade-like appearance. The fleshy snout is lined with sensitive pores that detect the electrical impulses given off by fish and other prey. (Any animal with muscles and a nervous system makes use of faint electrical impulses that can be sensed by sharks. Sharks use special sense organs to pick up detects these impulses.) The goblin shark’s protrusile jaws (jaws that are able to be thrust outward) are not attached to the skull but instead hang on a hinge underneath the long snout. A double set of jaw ligaments lets a goblin shark swing its jaws out to grab prey and retract (withdraw) them. Three rows of crooked, needlelike teeth line the jaws, helping snag squid, shrimp, and small fish.

The weird appearance of the goblin shark makes it one of nature’s most fascinating, if poorly understood, monsters. Because the sharks are so rarely seen, ocean experts know little about their lifestyle and reproduction. Fewer than 100 goblin sharks have been caught or sighted since they were first discovered in 1898, off the coast of Japan. However, experts do not think that the small number of sightings indicates that these odd sharks are rare. In fact, goblin sharks seem to be quite widespread across the world. Goblin sharks have been caught around Australia, Portugal, Mexico, New Zealand, South Africa, and off California and the Gulf Coast of the United States. The strange fish are rarely encountered because they lurk in deep waters, usually between about 200 and 900 feet (60 and 200 meters) below the ocean surface.

Being ugly seems to have worked out well for the goblin shark. Scientists have found fossil sharks that closely resemble the goblin shark in rocks that are more than 120 million years old. The bizarre fish is considered a “living fossil” as it is the last living member of a prehistoric group of sharks that stretches back million of years.

Monster Week continues—a week in which World Book features animals that look scary enough to be monsters.

Komodo dragon (© Pacific Stock/SuperStock)

September 8, 2015

Dragons do exist! The Komodo dragon can grow to more than 10 feet (3 meters) long and weigh as much as 365 pounds (165 kilograms). It can also smell you from miles or kilometers away. In addition, the Komodo is also venomous—that is, it makes a poison it injects into prey with its bite. Thankfully, however, this animal, the  largest living lizard, cannot fly—unlike its mythological namesake. The Komodo dragon lives on the tropical island of Komodo and a few other islands in Indonesia.

Komodo dragons have scaly bodies with long necks, strong claws, and sharp, sawlike teeth. They often scavenge, eating animals that are already dead. Their forked tongues have an organ of smell that helps them detect rotting carcasses (dead bodies) from several miles away. Dragons are also fierce predators, however. They are surprisingly fast, capable of running 13 miles (20 kilometers) per hour for a short time. The lizards hunt deer, wild pigs, and even water buffaloes.

The Komodo dragon inflicts long, deep wounds with its sharp teeth and strong neck. Often, it then patiently tracks its prey for days until the wounded animal weakens and collapses. People used to think that harmful bacteria living in the dragon’s mouth caused deadly infections to those animals unlucky enough to be wounded by the lizard’s jaws. In 2009, however, scientists discovered that the Komodo dragon is venomous. Glands in the dragon’s head secrete toxins that prevent blood from clotting and cause paralysis (loss of the ability to move voluntarily) and shock (a dangerous condition that can occur if the blood fails to circulate properly in the body).

Komodo dragons are at risk of extinction because people have destroyed much of their habitat. Fewer than 5,000 exist in the wild. Zoologists have had success with keeping and breeding dragons, however. You may be able to see some dragons (from a safe distance) at a zoo near you!

September 7, 2015

Monster Week begins—a week in which World Book features animals that look scary enough to be monsters.

Water bear (Credit: © Eye of Science/Science Source)

What kind of “bear” has eight legs tipped with razor-sharp claws and can survive in outer space? It is not the latest blockbuster movie monster, but a real life animal called the water bear, or tardigrade (TAHR duh grayd). And millions could be lurking in puddles nearby!

If you ever meet such a fearsome creature, you will be glad to know that the water bear is microscopic in size. Adults typically range from about 1/250 to 1/50 inch (0.1 to 0.5 millimeter) in length. That means they are just a little too small for people to see—smaller than a grain of salt. So, you have little to fear unless you are a defenseless bacteria or a delicious bit of microscopic plant matter. Water bears also dine on algae and on such small animals as rotifers, roundworms, and even other water bears.

The tiny tardigrade is not really a bear at all. Rather, it was named for its fearsome appearance and lumbering gait. Water bears are commonly found in puddles or thin films of water. They also sometimes live on moss, and some people have called them “moss piglets” because of their piglike snout.

Perhaps the most amazing thing about this microscopic monster is its ability to survive in nearly any kind of environment. Scientists have found tardigrades just about everywhere they have looked for them, from the frigid wastes of Antarctica to the simmering heat of hot springs. In a scientific experiment, water bears even survived exposure to the vacuum of space.

Many kinds of water bear are especially resistant to a more mundane menace—dehydration. To avoid drying out when water is scarce, a water bear can curl up into a ball and enter an inactive state. Water bears in this state are known as tuns. Water bears can survive as tuns for many years, becoming active again in minutes when the water returns.