by Sharon Oosthoek

Aboriginal rock paintings show that thylacines, or Tasmanian tigers, once lived all over Australia and on the islands of Tasmania and New Guinea. At the time, they were the largest meat-eating marsupials in the world. But then humans hunted them to extinction.

Benjamin, the last Tasmanian tiger, died in 1936 in Tasmania’s Hobart Zoo. That’s when zoo staff discovered the animal they thought was male, was in fact female. Their mistake was an easy one to make: both male and female Tasmanian tigers had pouches. Females raised their babies in the pouches, and males used them to protect their external reproductive organs. Tasmanian tigers’ scientific name, Thylacinus cynocephalus, actually means, “pouched dog with wolf head.”

Hunt and Be Hunted

While it was more related to kangaroos than wild dogs, the Tasmanian tiger had a dog’s body, a tiger’s stripes, and a muscular tail it used for balance. It could open its jaws a whopping 120 degrees. By comparison, a wolf can open its jaws about 90 degrees. Why such a big mouth? Thylacines were opportunistic hunters capable of taking down large creatures like kangaroos. They were strong hunters, but unfortunately that earned them a bad reputation.

“It was wrongly blamed in Australia for killing sheep,” says Andrew Pask, a molecular biologist at the University of Connecticut who studied the tigers. “People were really poor and were stealing each others’ sheep and blaming it on the Tasmanian tiger.” Because of these rumors, bounty hunters were given rewards to bring in dead thylacines. It didn’t take long before population levels dropped dangerously low.

Every few years since Benjamin’s death, people claim to have seen a Tasmanian tiger in the wild. In 2005, German tourists snapped photos of an odd creature that vaguely resembled a Tasmanian tiger. The blurry images inspired the imagination of those who want to believe the animals somehow survived extinction in Tasmania.

An Australian magazine, The Bulletin, offered $1.25 million to anyone who could capture a live, uninjured Tasmanian tiger. No one did, but the Tasmanian tiger was suddenly alive again in people’s imaginations…and so was its DNA.

A Mighty Mouse

In 2008, Dr. Pask led a team at the University of Melbourne in Australia that extracted a gene from a long-dead baby Tasmanian tiger. The baby had been preserved in alcohol for 140 years and kept in a museum. The gene they extracted was the thylacine’s blueprint for growing bone and cartilage, a tissue that acts like elastic to connect joints.

DNA is a bit like a set of instructions that tells a living organism how to grow. Each gene inside DNA contains instructions for specific characteristics, including the way bones, skin, and organs form.

Dr. Pask injected the thylacine gene into mouse embryos. As the embryos grew into adult mice, they developed bones and cartilage…without any apparent problems. That meant the Tasmanian tiger gene worked properly, long after the tiger had died.

“It’s important because we’d really like to understand how [the Tasmanian tiger] evolved its particular body plan,” says Dr. Pask. “We can look at the DNA and we can pick out the genes we think are important, but unless we put them into another living organism like a mouse, and see what they do, we don’t really know.”

Back in Order

In 2009, scientists from Penn State University studied some of the Tasmanian tiger’s genes using hair samples from two museum specimens. They successfully sequenced some of the animal’s DNA. That means they figured out the order, or sequence, of the instructions inside the genes.

Knowing the order of an animal’s genetic structure helps scientists understand how that animal is made — and it may even give some clues about why thylacines became extinct. “Tasmanian tigers were really interesting animals,” says researcher  Webb Miller. “It’s so sad they’re gone.”

Dr. Miller explains that by practicing on the Tasmanian tiger, he and his fellow scientists learned a lot about how to sequence the genes of other extinct species and species at risk of extinction.

The scientists have since found out that when a species is close to extinction, there is a noticeable lack of genetic diversity from animal to animal. When animals of the same species have slight differences in their genes, the species as a whole is able to fight off disease or adapt to dramatic environmental changes. But if their genetic code is the same, one disease can kill all of them. “Right now there are lots of cool animals teetering on the brink of extinction,” says Dr. Miller. He hopes that by breeding endangered animals with the widest possible range of genetic diversity, their babies might have a better chance of survival.

Tasmanian tigers may have disappeared 75 years ago, but they still have something to teach us today.

Mugshot:

Tasmanian Tiger

Size: About 60 centimeters at the shoulders

Weight: About 30 kilograms (65 pounds)
Color: Yellow-brown with dark brown stripes

Favorite food: Wallabies, wombats

Distribution: Tasmania, mainland Australia, and New Guinea
Last seen: Tasmania, 1936

Closest Relatives

Thylacines’ living cousins include numbats and small carnivorous marsupials called quolls, as well as the Tasmanian devil. Thylacines were not related to dogs or dog-like animals or tigers at all!

by Sharon Oosthoek

What plant is so menacing it’s an outlaw in the United Kingdom? If you move it across state borders in the United States without a permit, you’re in trouble? The answer is giant hogweed. The rock band Genesis even wrote a song about it threatening the human race in a plant-o-pocalypse scenario. (Yes, you can download the ringtone.)

“Everybody knows about yellow jacket wasp and bee stings,” says Jeff Muzzi, Manager of Forestry Services for Ontario’s Renfrew County, “but where things get a little more dangerous out there is with giant hogweed and [its relative] wild parsnip.”

The Burn That Lasts

Both plants can burn your skin, giving you blisters, and maybe leaving scars. Their sap contains chemicals called furocoumarins, which are phototoxic. That means the chemicals become active in the sun.

“After a day or two, your skin turns red and starts to blister. It’s ugly and can take up to a month to clear up,” says Muzzi. “But the photosensitivity (sensitivity to sunlight) will last for years. You won’t have any protection against the Sun — you’ll get instant sunburns every time you’re exposed.” If you’re unlucky enough get the sap in your eyes, you can go temporarily, or even permanently blind.

Settlers to North America brought wild parsnip with them from Europe over 100 years ago as a food source. Boil the roots and you have a nice starchy meal. Of course, the settlers knew enough to wear protective clothing at harvest time. Wild parsnip grows a bit taller than a mailbox and is topped with small clusters of yellow flowers.

Today, wild parsnips are everywhere, especially in roadside ditches and meadows. Giant hogweed, thankfully, has spread more slowly. Originally from the Caucasus region between Southwestern Asia and Europe, people brought them to North America because they thought they were pretty and liked to have them in their gardens. Giant hogweed stems reach up to five meters — that’s taller than a one-storey building — and are crowned with large umbrella-shaped cluster of small white flowers.

Painful Plants Aplenty

Plants can also cause you pain in more obvious ways — with sharp thorns and barbs for example. Botanists (scientists who study plants) call this a mechanical defense.

Roses and cacti have mechanical defenses. While their thorns can puncture your skin and make you bleed, you’ll easily recover unless your wound gets infected.

A more sneaky strategy is something botanists call a chemical defense. In this case, the liquid on a plant’s leaves or stems contains toxic chemicals that react with your skin, whether or not you expose it to the sun. Poison ivy, oak, and sumac all use a chemical defense by spreading an oily liquid called urushiol. (Well, it’s probably an accidental defense against humans since deer, goats, horses and birds eat parts of the plant.)

Urushiol is very sticky and doesn’t dry, so it clings to anything that touches it — skin, clothing, and pet fur. Even breathing in the smoke of a burning poison ivy, oak, or sumac can make your eyes and nasal passages red and tender. But if you touch poison ivy, you may not realize it until the next day, says environmental chemist, William Schlesinger, president of the Cary Institute of Ecosystem Studies in New York.

“You will wake up with a mild case of fluid filled blisters, which are extremely itchy and you can’t help but scratch,” he says. “That breaks the blisters and spreads the fluid across your body. If it’s bad, the blisters will coalesce (come together) and the entire surface of your skin will fall off and you’re left with one big, open, oozing sore.”  Eewww.

Unfortunately for the 80 percent of us who develop rashes from poison ivy, Dr. Schlesinger and other scientists have figured out the plant will get better at causing harm as we pump more carbon dioxide (CO₂) into the air. CO₂ is released by power stations that make electricity and comes out of the tailpipes of our cars, and it is causing the climate around the world to change.

Dr. Schlesinger and his team figured out the effect on poison ivy by buying CO₂ from a fertilizer factory and pumping it into a patch of forest in North Carolina until it reached levels scientists expect by 2050. They studied the forest from 1997 to 2004 and found the poison ivy grew faster and bigger, and its urushiol was more powerful. Ouch!

 Why urushiol?

Plants around the world contain the chemical urushiol. It’s purpose might have less to do with defense and more to do with protecting a plant’s wound.

 OW! Factor: OUTRAGEOUS plants

 • The manchineel tree’s sap, bark, and leaves are all highly toxic. It produces a sweet-smelling fruit that looks a lot like a crab apple, but don’t touch, and absolutely don’t eat. It contains a chemical that causes terrible pain and swelling.

Merely standing under the tree while it’s raining will cause your skin to swell and blister painfully. The tree grows in the Bahamas, the Caribbean, Central and South America, and in some parts of Florida.

• The giant stinging tree and the gimpie-gimpie are related trees that both grow in Australian rainforests and have large soft leaves covered in little hairs. The hairs contain a neurotoxin (a poison that affects nerve cells), and they can slide into your skin, delivering a sting that some people say is as painful as being scalded with boiling water and can last for months. You can even get sneezing fits just by standing next to a gimpie-gimpie.

by Sharon Oosthoek

Over three thousand years ago, a cargo ship sunk off the coast of Turkey while carrying tin, copper, glass, and ivory hippopotamus teeth — likely gifts from one king to another.

The boat rested on the sea floor for 3300 years before a Turkish diver looking for sponges spotted some strange-looking objects. He told his captain they looked like “metal biscuits with ears.”

The captain knew some underwater archeologists and told them about the discovery. The archeologists thought the biscuits might be ancient copper ingots — slabs of copper with handles to make it easier to move them.

That’s exactly what the young diver had found. And when the archeologists dove down to the ingots, they also found the royal ship. “The wreck is probably the most important ancient wreck yet found,” says archeologist George Bass, who led the research into the ship’s history.

Nobody knows for sure how many shipwrecks there are, says Bass, who created the Institute of Nautical Archeology to study important shipwrecks. Bass and the institute’s president, James Delgado, believe only a tiny number have been found.

“It’s a big ocean and we haven’t searched it all,” says Delgado. “We’ve maybe looked at five percent of it and we’ve found thousands of shipwrecks.”

Shipwrecks are often found by accident by divers or fishermen. Sometimes they’re found by reading historical records. Archeologists who have a good idea of where ships might have sunk will go out in a boat to look. They tow video cameras underwater, or use metal detectors that can find shipwrecks that carried iron cannons or anchors.

Archeologists may also launch small unmanned submarines to look around. “They dive and work on their own. They go back and forth just like you might mow a lawn — straight lines back and forth all day long,” says Delgado.

The submarines have sonar scanners that bounce sound waves off objects on the ocean floor. The scanner turns those sound waves into a kind of graph that shows the shape of things below the water — including shipwrecks.

Some of the best places to look are close to coastlines because boats often sink after hitting rocks near shore. The coastlines of countries with a long history of sailing are an especially good bet — from the Mediterranean to the South China Sea.

Cold, fresh water is often wreck heaven. No, or little salt, spares wrecks an attack from shipworm, which can chomp through a wreck in 10 years. Until recently, the Baltic Sea was a great place to find shipwrecks in good condition because it was shipworm-free, says Bass. The beautifully preserved Vasa, a 17^th century Swedish warship was found in the Baltic.

“Alas, perhaps because of global warming, shipworms are now being reported in the Baltic for the first time,” Bass says. In fact, shipworms have already attacked about a hundred sunken ships in the Baltic waters around Sweden, Germany, and Denmark. Scientists think salt-loving shipworms can tolerate the warming Baltic waters. The shipworm’s lunch, however, is the marine archeologist’s loss.

Who Owns a Shipwreck?

It depends. If a boat belonging to a country sinks — say a navy ship — it still belongs to that country and its government gets to decide what to do with it.

If a ship belonging to a person sinks, it could end up the property of an insurance company. That’s because ship owners pay insurance companies a little bit every month, and if their boat sinks, the company pays them what it thinks the boat is worth. After that, the company owns the boat.

But what happens when a wreck is so old no one remembers to whom it belonged? If it’s close enough to shore, the closest coastal country gets to decide what to do with it. Some countries require you ask permission before salvaging.

“Each country has their own different law,” says underwater archaelogist James Delgado. “But when you get out into the deep ocean, it’s no man’s land.”

That’s when a judge working in a special court called an Admiralty Court uses the Law of Salvage to decide who owns it. If you find a ship that’s been abandoned far out in the ocean — either floating or sunken — and you bring it, or parts of it, back to land, you can go to an Admiralty Court judge and argue that you saved the boat and deserve a reward for your work.

If the owner can be found, and they want the boat back, the judge could order them to pay you a reward. If the owner can’t be found, as is the case with many ancient wrecks, you could end up owning it.

by Sharon Oosthoek

 If attacked, humans scream. So do chimps — ditto for lots of animals. And guess what? Tadpoles scream, too.

            The discovery surprised Argentinian frog expert Guillermo Natale, who thinks he may be the first to record tadpole screams. While biologists knew tadpoles have lungs and a throat, it was a surprise to learn that they make a racket during an attack.

            Dr. Natale, who works at Argentina’s Universidad National La Plata, made the discovery while recording the mating calls of a species in Argentina called the Pacman frog. Listening through his underwater microphone, he suddenly realized he was also hearing tadpole shrieks.

            Curious, the scientist brought some frogs back to his lab with the idea that they would have babies, and he could listen to them. The adult frogs did not cooperate. So Dr. Natale turned to University of Ottawa biologist Vance Trudeau, an expert in getting frogs to breed in captivity.

            Dr. Trudeau succeeded and together he and Dr. Natale discovered Pacman tadpoles as young as 72 hours make a series of quick, metallic-like screams. But they only did it when they were touched with a small stick or when another Pacman tadpole bumped into them.  

            “We were flabbergasted,” says Dr. Trudeau. “We still are. It’s incredible. It’s like fetuses talking to each other.”

            Drs. Natale and Trudeau found that Pacman tadpoles made no sound when they put a different species of tadpole into the aquarium with them. Instead, they silently ate the other tadpole.

            The scientists think the tadpoles scream because they know other tadpoles of the same species might eat them. Pacman frogs and tadpoles are very carnivorous — which means they have a huge appetite for other animals, including tadpoles. As adults, the frogs even eat mice.

            Drs. Natale and Trudeau believe the screams are the tadpoles’ way of saying to their brothers and sisters: “We’re from the same family, please don’t eat me.”

            Scientists actually call the frogs Argentinean horned frogs. But most people call them Pacman frogs because they have big mouths like in the Pac-Man video game, and they will try to eat just about anything they can get their mouths around. Believe it or not, a popular name like Pacman means the frog is becoming a popular pet.

            Scientists worry that it will be harder to find the frogs in the wild as people trap and then sell them. If only the frogs could scream to frighten away humans.

Wasp Detectives

by Sharon Oosthoek

A tiny black-winged wasp is about to become a detective in the case of the emerald ash borer, a beetle that has killed millions of ash trees in Canada and the United States.    The shiny green beetles hitched a ride from Asia about 10 years ago, hidden in wood packing materials for products shipped to North American stores. It’s the beetle baby that kills trees — larvae feed under the bark and destroy the system that transports food and water to a tree.

Luckily, researchers at Ontario’s University of Guelph found that a native wasp, Cerceris fumipennis, can detect beetle-infested areas. The wasp leaves its nest in search of prey and in as little as half an hour knows if beetles are present. That’s good news because the faster we find the emerald ash borers, the faster we can stop them. Fewer trees will have to be cut down or injected with expensive pesticides to stop the beetles’ spread.

“It’s like the wasp is Sherlock Holmes and we’re his assistant Watson,” says bug expert Philip Careless, who was a master’s student at the University of Guelph when he helped figure out the wasps make good investigators. “You have a partner — which happens to be a wasp — that is awesome at finding where these pests are that are moving into our neighborhoods to eat our trees.”

Careless, who is now a bug expert with the Canadian Food Inspection Agency, says the wasp is good at finding the beetle because it’s one of its favorite meals. Mother wasps bring the beetles back to the nest to feed their larvae. Careless knows this because he visited places known to have emerald ash borers, and then he looked for wasp nests on the nearby ground.

After the mother wasps left their nests to hunt, he put clear plastic cups over the nest entrances. When a mother returned and found her nest blocked, Careless grabbed her groceries. He found — you guessed it — emerald ash borers.

Unfortunately, the wasps kill too few emerald ash borers to stop them from spreading. That’s where humans come in. Forest managers in the U.S. are now training volunteers, including scouts and guides, to watch nests and tell them when the wasps bring back emerald ash borers. In Canada, Careless and his team will spend this summer finding out where the nests are and next year volunteers can take over.

Want to volunteer, but you’re afraid of a wasp sting? No worries. “These wasps have a stinger, but they don’t use it in defense. They use it to paralyze prey,” Careless says.  “We grab them all the time when we steal their groceries and they never sting us.” Beetles, beware.