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How Bugs From Australia Settled African Islands

When the Mascarene islands—Mauritius, Réunion, and Rodrigues—were born, they were blank slates. Unlike some other islands, they didn’t break off from a larger landmass, taking plants and animals with them. Instead, they rose right out of the water, formed by volcanic activity in the Indian Ocean off the coast of East Africa. Life there had to start from scratch. 

The islands collected colonizers and wayward travelers—a seed here, an egg there—over about 10 million years. Some of these species, like the islands’ most famous resident, the dodo, are no longer around, but, German zoologist Sven Bradler says, the Mascarenes are still home to a “remarkably diverse, endemic, and threatened concentration of flora and fauna.”

The islands’ location led scientists to assume that the plants and animals there arrived from nearby Madagascar and the African mainland. That’s the case for most of them, but Bradler’s research, recently published in the journal BMC Evolutionary Biology, has revealed that at least some traveled from much farther away: Australia.  

Among the Mascarenes’ animals are several types of Phasmatodeans, commonly called stick bugs or walking sticks. These large insects mimic plants for camouflage. The Mascarene stick bugs are diverse in appearance and behavior, but share some similarities with other African stick bugs. Traditionally, they’ve been placed in four different groups and descend, the thinking goes, from different, unrelated lineages of African stick bugs that all found their way to the islands at different times. 

When Bradler and his team mapped out the evolutionary histories and relationships of 120 stick bug species from around the world (including, for the first time, the ones on the Mascarenes and elsewhere in the Indian Ocean), though, they found that this traditional view was way off the mark. 

Their results suggest that the Mascarene stick bugs aren’t the descendants of several types of African bugs that made separate journeys to the islands; in fact, they don’t appear to be closely related to African stick bugs at all. Instead, they descend from a lone species of stick bug that originated in Australia, some 3000 miles away. This common ancestor was a member of bug group Lanceocercata, from which they diverged around 22 million years ago. Over time, the Mascarene insects evolved and diversified, and converged on some of the same traits and features as their African neighbors, leading to confusing similarities. 

The trip from Australia to the Mascarenes would be a long, perilous one for most animals, and stick bugs seem to be at a distinct disadvantage when it comes to such long-distance travel. While many species have wings, they’re poor flyers and can usually only use their wings to slow their descent from trees to the ground. They’re not cut out for trans-oceanic journeys—but with some luck, their eggs could pull it off. Stick insect eggs are hard-shelled and seed-like, and can survive for months at a time floating on water. The researchers think that the eggs of the Masacarene bugs’ Australian ancestor floated on a strong ocean current to get to the islands, maybe attached to a stick (how apt) that acted like a raft for them.

If you’ve been paying attention to the numbers, you might have noticed that something is amiss with this explanation: These bugs are far older than the islands they call home. While the Mascarenes’ founding stick bugs appear to have arrived around 22 million years ago, the oldest of the islands only formed 8–10 million years ago.

There's a possible explanation for this mismatched timeframe. There’s evidence that the Mascarenes had sibling islands, formed from the same volcanic hot spot, that rose above sea level around 30 million years ago and have since sunk back under the ocean. Bradler thinks that the Australian stick bug’s eggs likely landed on one of these lost islands and the bugs used them as stepping stones to get where they are now. When the colonists hatched, they evolved and speciated before moving on to the newly formed Mascarenes. 

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Animals
20 Black-and-White Facts About Penguins
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To celebrate World Penguin Day (which is today, April 25), here are a few fun facts about these adorable tuxedoed birds.

1. All 17 species of penguins are found exclusively in the Southern Hemisphere.

2. Emperor Penguins are the tallest species, standing nearly 4 feet tall. The smallest is the Little Blue Penguin, which is only about 16 inches.

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3. The fastest species is the Gentoo Penguin, which can reach swimming speeds up to 22 mph.

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4. A penguin's striking coloring is a matter of camouflage; from above, its black back blends into the murky depths of the ocean. From below, its white belly is hidden against the bright surface.

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5. Fossils place the earliest penguin relative at some 60 million years ago, meaning an ancestor of the birds we see today survived the mass extinction of the dinosaurs.

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6. Penguins ingest a lot of seawater while hunting for fish, but a special gland behind their eyes—the supraorbital gland—filters out the saltwater from their blood stream. Penguins excrete it through their beaks, or by sneezing.

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7. Unlike most birds—which lose and replace a few feathers at a time—penguins molt all at once, spending two or three weeks land-bound as they undergo what is called the catastrophic molt.

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8. All but two species of penguins breed in large colonies of up to a thousand birds.

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9. It varies by species, but many penguins will mate with the same member of the opposite sex season after season.

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10. Similarly, most species are also loyal to their exact nesting site, often returning to the same rookery in which they were born.

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11. Some species create nests for their eggs out of pebbles and loose feathers. Emperor Penguins are an exception: They incubate a single egg each breeding season on the top of their feet. Under a loose fold of skin is a featherless area with a concentration of blood vessels that keeps the egg warm.

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12. In some species, it is the male penguin which incubates the eggs while females leave to hunt for weeks at a time. Because of this, pudgy males—with enough fat storage to survive weeks without eating—are most desirable.

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13. Penguin parents—both male and female—care for their young for several months until the chicks are strong enough to hunt for food on their own.

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14. If a female Emperor Penguin's baby dies, she will often "kidnap" an unrelated chick.

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15. Despite their lack of visible ears, penguins have excellent hearing and rely on distinct calls to identify their mates when returning to the crowded breeding grounds.

16. The first published account of penguins comes from Antonio Pigafetta, who was aboard Ferdinand Magellan's first circumnavigation of the globe in 1520. They spotted the animals near what was probably Punta Tombo in Argentina. (He called them "strange geese.")

17. An earlier, anonymous diary entry from Vasco da Gama's 1497 voyage around the Cape of Good Hope makes mention of flightless birds as large as ducks.

18. Because they aren't used to danger from animals on solid ground, wild penguins exhibit no particular fear of human tourists.

19. Unlike most sea mammals—which rely on blubber to stay warm—penguins survive because their feathers trap a layer of warm air next to the skin that serves as insulation, especially when they start generating muscular heat by swimming around.

20. In the 16th century, the word penguin actually referred to great auks (scientific name: Pinguinus impennis), a now-extinct species that inhabited the seas around eastern Canada. When explorers traveled to the Southern Hemisphere, they saw black and white birds that resembled auks, and called them penguins.

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6 Myths About Animals, Debunked
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It’s easy to think we understand animals: They’re present in every part of our culture, from the movies we watch to the clichés we use. But the way a species functions in the wild is often worlds apart from a stereotype or cartoon. This gulf between misconceptions and reality is the theme of Lucy Cooke’s new book, The Truth About Animals.

"We have a habit of viewing the animal kingdom through the prism of our own existence, and that trips us up and obscures the truth,” Cooke, a zoologist and founder of the Sloth Appreciation Society, tells Mental Floss. “I think it's time we rebrand the animal kingdom according to facts and not sentimentality.”

As Cooke examines in her book, the real world is one in which pandas are virile lovers and sloths are master survivalists. These are just a few of the myths that were debunked in The Truth About Animals.

1. PANDAS HAVE LOW SEX DRIVES.

Pandas have long been blamed for their own precarious position in the animal kingdom. The species is in danger, some people claim, because pandas are reluctant to or just plain bad at copulating. If only they would get off their furry behinds and get it on, there would be more of them.

In The Truth About Animals, Cooke debunks this modern myth. Pandas have been living in the wild for 18 million years—long before humans swooped in to act as their savior—and that wouldn’t be the case without healthy sex habits. It’s true that pandas are difficult to breed in captivity, and the several failed attempts of zoos to produce a baby panda throughout the 20th century is likely what led to this stereotype. But the bears are much more responsive to members of the opposite sex in the wild. The female chooses who she mates with, moaning from high in a bamboo tree while several males on the ground compete for her attention. Once the bears have paired off, they can have sex over 40 times in one afternoon.

2. SLOTHS ARE LAZY.

Cooke was inspired to write her book by sloths, which she describes to Mental Floss as “highly successful, highly evolved” creatures. Not everyone agrees: More than perhaps any other animal, sloths have become synonymous with laziness and sluggishness, and today they’re held up as an example of evolutionary failure.

The reality is that sloths are much more impressive than their appearance suggests. They’ve been around since 64 million years ago—earlier than wooly mammoths and saber-toothed tigers—and they have their slow and steady nature to thank for their success. Sloths have a remarkably slow digestive system and a low-calorie diet, so they expend as little energy as possible, not out of laziness, but out of survival instinct. A sloth is awake for more than half the day, and when necessary it can scramble up a tree at speeds approaching 1 mph. It spends most of its day in a still, seemingly trancelike state, but it isn’t wasting its potential: It’s conserving energy so it can maintain its dominant spot in the evolutionary tree.

3. PENGUINS ARE LOYAL LOVERS.

Emperor penguins, the most famous of the bird group, are known for splitting parenting duties between mated pairs, with the father incubating the egg while the mother gathers food for her family. This has led some to praise penguins as the reflection of ideal, moral family dynamics in the animal kingdom, but these people should probably find a different analog. Though the parents of any given chick may raise their offspring together, penguins aren’t monogamous: 85 percent of emperor penguins find a new partner from one breeding season to the next. Penguins are also some of the only animals known to exchange goods for sex. Adélie penguins need rocks to build up their nests during warmer months when meltwater threatens their eggs. With no parenting duties to distract them, bachelor penguins end up collecting more stones than they need, so some females will sometimes trade a one-off sex session for one of their pebbles.

4. VULTURES STALK DYING PREY.

Watch enough survival movies and you’re bound to see a shot of a hungry vulture trailing behind the starving protagonist, waiting for them to lie down and die. The myth that vultures stalk their prey while it’s still alive and have the power to predict death is a persistent one, but that doesn’t make it accurate. The scavengers have no interest in living animals and will only seek out meat from dead and decaying corpses. Rather than reaper-like premonitions of mortality, turkey vultures and greater and lesser yellow-headed vultures use their noses to locate their meals. They join kiwis and kakapos on the small list of birds with highly-developed olfactory glands. Without a strong sense of smell, other New World vultures and all Old World vultures primarily rely on sight to find food. Some New World vultures like black vultures have adopted a different strategy: They'll follow turkey vultures to their prey, taking advantage of their sensitive noses.

5. ALL BATS ARE RABID BLOOD-SUCKERS.

Bats may be the animals most closely associated with the horror genre. They crave blood, so the myth goes, and though a bat latched onto your neck won’t be able to suck you dry, it will likely infect you with a nasty case of rabies.

According to Cooke, there are many problems with the statement above. Bats are poor stand-ins for their fictional vampire counterparts; only three species of bats drink blood—the common vampire bat, the hairy-legged vampire bat, and the white-winged vampire bat—while most prefer fruit or insects. After climbing onto its prey, the vampire bat locates where the blood is flowing with the heat sensor on its nose, and then, using its sharp front teeth like shears, it cuts away any hair that might be blocking the skin. Rather than biting down and sucking like Dracula, the bat creates a small incision and laps up blood from the open wound. They can recognize an individual animal's breathing patterns and return to feed on it the following night, taking advantage of the reliable blood source.

Bats are rarely rabid, with just .05 percent of them carrying the disease—less than dogs or raccoons. The image of a bat getting tangled in your hair also has no basis in reality: Their sophisticated echolocation system signals them to turn long before they have a chance to collide with your head.

6. FEMALE HYENAS HAVE PENISES.

Hyena genitalia has been baffling scientists for centuries. Member of both sexes appear to have a penis, while in females there’s no external vagina to be found. Scientists originally thought that hyenas must be hermaphrodites, but the true explanation is even more unusual. Though it’s often referred to as a pseudo-penis, female hyena genitalia doesn’t produce sperm, technically making it a nearly 8-inch-long clitoris. This appendage is also saddled with all the same duties as a conventional female organ, including giving birth to hyena pups.

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