Sandra Lindsay, left, an African American nurse, is injected with the COVID-19 vaccine developed by Pfizer on Dec. 14, 2020, in the Queens borough (section) of New York City. The rollout of the vaccine, the first to be given emergency authorization by the Food and Drug Administration, began the biggest vaccination effort in U.S. history.
Credit: © Mark Lennihan, Getty Images

On Monday, Aug. 23, 2021, the United States Food and Drug Administration (FDA) fully approved the two-dose Pfizer vaccine for COVID-19. The FDA has granted full approval of the vaccine for those aged 16 years and older. Full approval of a vaccine will make it easier for public and private organizations to require vaccinations. This includes hospitals, active-duty military, and schools.

The coronavirus disease COVID-19 has killed more than 4 million people and infected more than 200 million people around the world. The first countries with access to a vaccine began vaccinating their citizens in December 2020. Almost 5 billion doses of a vaccine preventing COVID-19 have been administered to people around the world.

In late November 2020, the companies Pfizer and Moderna each applied for emergency approval from the FDA for their COVID-19 vaccines. The two companies are among dozens of drugmakers that worked tirelessly to develop a vaccine against the deadly virus. Because the vaccine was authorized for emergency use after a clinical trial of 40,000 people, many citizens were hesitant to receive the vaccine. Full approval of the vaccine may assure some of those yet to get the shot of the vaccine’s safety.

Pfizer and Moderna began clinical trials in July. During these trials, participants were given either the vaccine or a placebo. A placebo is a substance that contains no active ingredient. Comparing infection rates in subjects who received the placebo with those among subjects who got the vaccine can help determine if the vaccine is effective. In the Pfizer and Moderna clinical trials, half the participants were given a placebo of saltwater, and half were given the vaccine. The researchers then waited to see who might get sick. The results were very promising—both vaccines were about 95 percent effective in preventing COVID-19. By contrast, commonly administered influenza vaccines (known as flu shots) are 40 percent to 60 percent effective.

An image of Venus, made with data recorded by Japan’s Akatsuki spacecraft in 2016, shows swirling clouds in the planet’s atmosphere.
Credit: PLANET-C Project Team/JAXA

Venus is heating up—figuratively, that is. It has always been the hottest planet in the solar system, with surface temperatures of about 870 °F (465 °C). But new findings from the mysterious planet have been pouring in. Soon, a new generation of space probes will transform Venus from a sleepy solar system backwater to a bustling hub of scientific discovery.

Venus is the second planet from the sun. It is known as Earth’s “twin” because the two planets are so similar in size. The diameter of Venus is about 7,520 miles (12,100 kilometers). This diameter is about 400 miles (640 kilometers) smaller than that of Earth. No other planet comes nearer to Earth than does Venus. At its closest approach, it is about 23.7 million miles (38.2 million kilometers) away.

But Venus is better described as Earth’s evil twin, in respect to its withering conditions. In addition to the high temperatures, the atmospheric pressure is 90 times greater than that on Earth. Carbon dioxide makes up most of the atmosphere. The skies are strewn with clouds of sulfuric acid.

Scientists sent several probes to learn more about the planet in the 1960’s and 1970’s. But as space agencies learned of its inhospitable conditions, they concentrated their efforts elsewhere, particularly Mars. The last United States National Aeronautics and Space Administration (NASA) mission to study Venus, called Magellan, launched in 1990. Thus, scientists know relatively little about Venus, despite its close proximity to Earth and its similar size.

Despite the dearth of missions in recent years, planetary scientists continue to scan the planet with Earth-based instruments and reanalyze older data. They have returned surprising results.

Last year, a team of scientists announced that they had discovered a gas called phosphine in Venus’s atmosphere. Many living things on Earth produce phosphine; and scientists have not been able to identify any non-biological processes on Venus that might produce it. This raised the possibility that microbial life could exist in Venus’s atmosphere, where the conditions are much milder. But the discovery has been controversial. Other teams have failed to find any phosphine signature.

Last month, a team led by researchers at Queen’s University Belfast left the floating-Venusian-microbes idea high and dry. They found that Venus’s atmosphere does not contain enough water vapor to support life, irrespective of the presence of phosphine. The team determined that even the most extreme microbes on Earth require an environment with dozens of times more water than is available in Venus’s atmosphere.

Another recent study has shed light onto possible changing of Venus’s surface. Previously, Earth was the only rocky planet known to have a moving surface. A team lead by Paul Byrne, a professor at North Carolina State University, found evidence that parts of Venus’s surface might be slowly moving today. Earth’s crust slowly reshapes itself by a process called plate tectonics. Large pieces of the surface, called plates, subduct (sink) under one another, forming mountain ranges and other features. New crust forms along the ridges where the plates pull away from each other. In contrast, Byrne’s team found that pieces of Venus’s crust move like pack ice in polar oceans. Learning more about crust movement on Venus will help scientists understand how such processes develop on other planets, including Earth and exoplanets that might harbor life.

Last month, space agencies announced that not one, but three missions will be exploring Venus in the next 15 years. On June 2, NASA announced it is sending two mission to Venus. The missions were selected as part of part of NASA’s lower-cost Discovery Program. NASA expects to launch both missions between 2028 and 2030.

VERITAS (Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy) will orbit the planet and map its surface with greater detail than ever before. It will allow scientists to better understand the planet’s features.

DAVINCI+ (Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging) consists of a sphere that will plunge through Venus’s thick atmosphere, studying the atmosphere’s composition. The DAVINCI+ mission planners are seeking evidence of an ocean of water that might have covered Venus’s surface eons ago.

There are other players in the new Venus boom. Last year, American company Rocket Lab announced plans to launch a small probe to Venus as early as 2023. And on June 10, just over a week after NASA’s selection DAVINCI+ and VERITAS, the European Space Agency (ESA) announced that it would also be sending a probe Venus. The EnVision orbiter will search for signs of current and former tectonic activity and the presence of a past ocean. EnVision is scheduled to arrive at Venus in 2034 or 2035.

The desire to learn more about Venus is fed by more than just curiosity about our nearest neighbor. Astronomers are looking for signs of life on exoplanets. But Venus and Earth would look quite similar from light-years away. Learning more about Venus and how it evolved to become so different from Earth will help astronomers better weed out Venus-like exoplanets in their search for ones that are more like Earth.

American businessman Jeff Bezos poses with the other passengers New Shepard’s first crewed flight to space. From left to right: Mark Bezos, American executive; Jeff Bezos, founder of Blue Origin; Oliver Daemen, Dutch physics student; and Wally Funk, American pilot and aviation expert. Credit: © Blue Origin

The world’s richest man, his brother, an 82-year old woman, and a physics student sealed themselves up in a tiny capsule and flew into space. This might sound like the setup of a joke, but that’s what happened today. American businessman Jeff Bezos flew to space with three companions in the first crewed flight of the New Shepard rocket, developed by Bezos’s aerospace company Blue Origin. Their flight came exactly 52 years after the Apollo 11 moon landing.

The New Shepard rocket takes off on July 20 carrying its first group of passengers. Both the booster and the capsule landed back near the launch pad about 10 minutes later.
Credit: © Blue Origin

The rocket, a small reusable booster and capsule called New Shepard, took off this morning from Texas. New Shepard is named after Alan Shepard, the first American to reach space. The rocket rose more than 100 miles (61 kilometers) straight into the air. The booster separated from the capsule and landed using its engines. The capsule floated back down to the ground on parachutes. The whole flight lasted about 10 minutes. Along for the ride were Bezos’ brother Mark, the American aerospace pioneer Mary Wallace “Wally” Funk, and 18-year-old physics student Oliver Daemen.

Bezos, who made billions from his online shopping company Amazon, founded Blue Origin in 2000. The company spent years developing and testing the New Shepard rocket. In 2015 a New Shepard rocket reached the edge of space and then returned safely to Earth, landing vertically. It was the first rocket to do so, narrowly beating the first successful landing of SpaceX’s much larger Falcon 9 by less than a month.

The participants of the New Shepard flight set multiple records. But Bezos lost out on his own record, however. Until a couple of weeks ago, it appeared that he was going to be the first mogul to fly to space aboard his own spacecraft. But that honor instead went to the British businessman Richard Branson, who flew on a spaceplane of his own space tourism company. The July 11 mission was originally scheduled to be a test flight, but Branson added himself to the manifest after Blue Origin announced Bezos’s flight.

Wally Funk trained as an astronaut in the 1960’s. She was part of a privately-funded program that subjected women to the same testing and training as the men who became part of the United States’ Mercury Program. Although these women, later known as the Mercury 13, were not permitted to become astronauts, Funk never quit on her dream of going to space. Earlier this year, Bezos surprised Funk with a seat on the inaugural crewed flight. At 82, she became the oldest person to go to space. She surpassed the American astronaut and senator John Glenn, who returned to space in 1998 at the age of 77 aboard the space shuttle.

Oliver Daemen became the youngest person to go to space. He surpassed the American astronaut Sally Ride, who was 32 when she flew aboard the space shuttle Challenger in 1983. Daemen also became the first paying space tourist to fly aboard a privately-developed spacecraft. A handful of tourists have gone to space already. But all of these were aboard Soyuz rockets developed and launched by the Russian government. Only Virgin Galactic employees flew aboard Branson’s flight.

This fourth seat was highlighted by profligate spending, mystery, and intrigue. Blue Origin put up the seat for auction, with the money being donated to the company’s charity. An anonymous bidder paid $28 million for the seat. But last week, the company announced that the bidder had a scheduling conflict and would go on a later flight instead. Blue Origin offered the seat to Dutch investor Joes Daemen, who had purchased a seat for a later Blue Origin flight. He gave the seat to his son, Oliver.

Blue Origin will start offering rides to other paying customers soon. Although the Billionaire’s Space Race is over, the battle for control of the space tourism market is just beginning.

Bandy-bandy © Ken Griffiths, Shutterstock

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.

The bandy-bandy is a small Australian snake known for its striking black and white stripes. There are several species (kinds). When threatened, a bandy-bandy may raise its body off the ground in hypnotizing loops, perhaps to intimidate or confuse predators. For this reason, it is also known as the hoop snake. 

When the serpent is on the move, its pattern of  black and white bands may confuse and dazzle predators. Zebra stripes may serve a similar function. The stripes confuse predators as to which direction the snake is moving, allowing it to make a quick escape. This trick is sometimes called “flicker fusion.”

The bandy-bandy lives throughout northern and eastern Australia. It lives in a variety of habitats, from coastal rain forests to woodlands, scrublands, and even deserts. Bandy-bandies are burrowing snakes, often found sheltering under rocks or logs. The snakes emerge at night to hunt for prey.

The bandy-bandy may feed largely or exclusively on smaller snakes called blind snakes. It has a weak venom that is not thought to be dangerous to people. Owls, cats, foxes, and larger reptiles may prey on bandy-bandies.

The female bandy-bandy lays from 2 to 15 eggs. Adults reach 24 inches (60 centimeters) in length.

A giant wood moth was found at Mount Cotton State School in Queensland by builders.
Credit: © Mount Cotton state school

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.

Last month, the children at Mount Cotton State School in Queensland, Australia, got a new class pet: a giant wood moth. Construction workers found the grey, fuzzy-looking insect resting on a side of the building. Given that the giant wood moth can have a wingspan of up to 9 inches (23 centimeters), it must have been covering a good portion of the wall!

The giant wood moth, or Endoxyla cinereus, spends much of its life as a larva inside Australia’s native eucalyptus trees. A larva is an active, immature stage of an animal. A giant wood moth remains in this larva stage for three years. But, as an adult, the moth lives for only one week. It dies after mating and laying eggs.

The students enjoyed looking at the moth. But they couldn’t bring the moth to such school activities as playing at the park or eating in the cafeteria. Among many other reasons, the giant moth couldn’t eat school lunch, because adult moths do not eat. Instead, they get energy from fat reserves that they build up during the larva stage.

The workers who discovered the giant wood moth recognized the insect by its large size and grey color. They did not mistake the moth for its colorful counterpoint: the butterfly.

Moths differ from butterflies in a number of important ways. For example, most moths fly at dusk or at night. The majority of butterflies fly during the day. Among most moths, the hind wing is attached to the front wing by a hook or set of hooks, called a frenulum. Butterflies lack a frenulum. In addition, most butterflies have antennae that widen at the ends and resemble clubs. The antennae of most moths are not club-shaped. Many male moths have larger antennae than do female moths.

This rock, called “Máaz” (the Navajo word for “Mars”), is the first feature of scientific interest to be studied by NASA’s Perseverance Mars rover.
Credit: NASA/JPL-Caltech

When you’re exploring a planet, you have to name things. It’s a great way to memorialize your discoveries, but it also prevents confusion: are you going to study This Rock, That Rock, or The Other Rock?

The United States National Aeronautics and Space Administration (NASA) mission Mars 2020 is hard at work exploring Mars. The mission’s rover, Perseverance, landed on Feb. 18, 2021, in Jezero Crater. The mission planners have been naming important surface features in the Navajo language. This decision wasn’t planned before the rover landed, but came about by happy circumstance.

Landing on another solar system body is tough. Mission planners can guide a lander to a general destination, but they cannot pinpoint an exact landing site. Mars 2020 mission planners could guide Perseverance to Jezero Crater, but they could not know where in the 28-mile (45-kilometer) wide crater the rover was going to land. Therefore, mission planners studied the entire crater to prepare for landing. They divided the crater into several sections, naming each after a place on Earth—including U.S. national monuments—that the section resembled in some way.

Perseverance landed within the section that planners had named after Canyon de Chelly National Monument. This national monument, known for its huge, colorful, steep-walled canyons, lies entirely within the Navajo reservation. The Navajo are one of the largest Native American groups in the United States. The Navajo reservation, which covers 16 million acres (6.5 million hectares), is the nation’s biggest reservation. It includes parts of Arizona, New Mexico, and Utah.

Canyon de Chelly National Monument (“Tséyi’” in Navajo) in Arizona is located on Navajo Nation land. Members of NASA’s Perseverance rover team, in collaboration with the Navajo Nation, has been naming features of scientific interest with words in the Navajo language.
Credit: NASA/JPL-Caltech

NASA’s Mars mission scientists informally name important features to make them easier to identify. Mars 2020 mission scientists were inspired by the name of their landing site to nickname features in the Navajo language. They teamed up with NASA Jet Propulsion Laboratory (JPL) scientist Aaron Yazzie, who is Navajo, to seek permission from the Navajo Nation. The nation’s government approved the idea and developed a list of potential names. The first name to be used was Máaz, the Navajo word for Mars, for a rock near the landing site. Navajo officials also included the translation for Perseverance: Ha’ahóni.

Perseverance has to be “taught” the language, since the computer languages the rover uses cannot process the special characters and diacritical marks used in the written Navajo language. Mars 2020 team members are working to develop better transliterations using the English alphabet.

This is not the first time the Navajo language has played an outsized role in United States history. During the United States’ involvement in World War II (1939-1945), Navajo radio operators sent secret messages using a code based on the Navajo language. At the time, Navajo was an unwritten language known to few people outside of the Navajo Nation. Its complex structure, difficult pronunciation, and singsong qualities made it nearly impossible to decipher. Although Imperial Japanese forces could overhear the messages, they never managed to decode them. The Navajo radio operators, called code talkers, have been honored for their service in the war.

Mars 2020 has shed its proverbial training wheels and is breaking new ground in the exploration of the Red Planet. The helicopter Ingenuity, another part of the mission, conducted its first flight on April 19. Engineers are now pushing Ingenuity further, conducting longer, more challenging flights. The craft’s performance will gather valuable information for future Mars flyers. Perseverance’s robotic arm began conducting science on May 11. As the mission continues to explore, planners will continue to nickname features in the Navajo language—a tribute to the Navajo people, their culture, and the land they call home.

Periodical cicada
Credit: © Thinkstock

They’ve waited underground for 17 years. Now, they’re coming to the surface to burst out of their skins, give off earsplitting screeching sounds, bore into trees, and cover the ground with their carcasses. But—like many blockbusters over the past year and a half—you can’t view this spectacle in movie theaters. You can’t even stream it on Netflix. If you live in the eastern U.S. Midwest or Middle Atlantic, this summer’s invasion is coming to a backyard or forest preserve near you. It’s called Brood X.

Brood X is not a movie, but a group of cicadas emerging this month. A cicada is a large insect with four thin wings which it folds over its body like a peaked roof. It can measure 1 to 2 inches (2.5 to 5 centimeters) long. It has a wide head and short, bristlelike antennae (feelers).

Just as crickets serenade us on warm summer nights, cicadas make up the soundtrack of hot summer afternoons. The male cicada makes two drumlike membranes (thin sheaths of skin) on the abdomen vibrate rapidly. This produces a characteristic buzzing sound. The sound attracts females or calls large numbers of males together. Each species (kind) of cicada has its own song. Male cicadas often assemble in large groups and produce a loud chorus of sounds.

Many of us hear cicadas every summer. So why is this summer different? There are thousands of species of cicadas. They can be roughly divided into two types: annual cicadas and periodical cicadas. As their name suggests, annual cicadas can be heard every year. But periodical cicadas emerge on 13- or 17-year cycles. Brood X is a 17-year periodical cicada, having last emerged in 2004. Other brood numbers (X is the Roman numeral for 10) emerge in different years in different regions. But Brood X is one of the largest and most famous.

Why do periodical cicadas emerge this way? It has to do with evading predators. Cicadas are a hearty, protein-packed snack for birds, raccoons, foxes, opossums, fish, spiders, and practically any other animal. Humans eat them, too! Cicadas are vulnerable when they are emerging. They don’t bite or sting and are clumsy flyers. But when so many cicadas emerge at once, there are just too many for predators to eat. Even with every predator’s belly filled with cicadas, billions or trillions survive to reproduce.

Seventeen years is a long time. Potential predators can’t rely on a food source that appears so infrequently. So, although animals take advantage of the cicada smorgasbord, nothing has evolved to rely on them exclusively.

Where do periodical cicadas go for all those years? After the adults mate, the female bores into twigs of bushes and trees with a sawlike organ near the tip of her abdomen. She lays her eggs in the holes. The eggs hatch in a few weeks and the young cicadas, called nymphs, drop to the ground. They live in the soil and eat roots for years—17 years in the case of Brood X.

The periodical cicadas will spend the summer shedding their skins and making lots of noise. However you decide to spend your summer, have fun and keep an ear out for Brood X!

A new archaeological discovery is seen in Luxor, Egypt.
Credit: © Zahi Hawass Center for Egyptology

In early April 2021, Egyptian archaeologists announced their discovery of a previously unknown ancient city that had been buried largely intact for thousands of years. The city, given the name Aten or The Rise of Aten, was built around 3,500 years ago near Egypt’s Valley of the Kings, a narrow gorge that was used as a cemetery by the pharaohs (kings) of ancient Egypt.

Egyptologists (scholars who study ancient Egypt) compared the importance of the discovery of Aten to the discovery of the tomb of Tutankhamun (sometimes called King Tut) in 1922. Others compare this site to Pompeii, an ancient city in Italy that disappeared after the eruption of Mount Vesuvius in A.D. 79. Like Pompeii, Aten promises to give scholars a rare and relatively complete view of the daily life of ancient Egyptian commoners. Most other important discoveries in Egyptology involve tombs of pharaohs and other wealthy Egyptians.

The remarkable site of Aten preserves the ruins of many homes built of mud brick walls about 9 feet (3 meters) high. Archaeologists also found the remains of tools and other utensils used in the daily life of ancient Egyptians along with jewelry, scarab charms, pottery, and tools for making bread, yarn, cloth, and glass. The number of homes and workshops at the site shows that the city had a large population. The archaeologists have discovered a number of burials that preserve the skeletons of some of the city residents. Unlike wealthy people in ancient Egypt, the burials of these commoners were not preserved as mummies.

Pottery found at the site bore an inscription that allowed scholars to determine it was manufactured during the reign of the pharaoh Akhenaten. He ruled ancient Egypt from about 1353 to 1336 B.C. His wife, Queen Nefertiti, was famous for her great beauty and her dedication to her husband’s teachings. Akhenaten was originally known as Amenhotep IV. He was the son of Amenhotep III, one of the most powerful pharaohs of ancient Egypt’s New Kingdom period (1539-1075 B.C.). During the New Kingdom, Egypt became the largest and strongest empire in the ancient world.

As pharaoh, Amenhotep IV was a religious reformer. He chose Aten as the only god of Egypt and dismissed the many gods and goddesses of the ancient Egyptian pantheon. Aten had been a little-known sun god worshiped mainly in the ancient Egyptian city of Thebes. Amenhotep was so devoted to the worship of Aten that he changed his own name to Akhenaten, meaning servant of Aten. Akhenaten’s religious reforms, known as the Amarna Revolution, led to an outpouring of art and sculpture that glorified the Aten. But the changes angered many Egyptians who wished to continue worshipping the old gods.

After the death of Akhenaten, his successor Tutankhaten removed -aten from his name and became Tutankhamun. He restored the old state religion, allowing the worship of the many old gods as well as Aten. Later pharaohs destroyed or removed all monuments built by or in honor of Tutankhamun and others who had accepted Aten as Egypt’s chief god. The city of Aten was abandoned and eventually became buried in the desert sand for more than 3,000 years until its rediscovery this year.

Indian-born American astronaut Kalpana Chawla
Credit: NASA

May is Asian American and Pacific Islander (AAPI) Heritage Month. All month long, Behind the Headlines will feature AAPI pioneers in a variety of areas.

In 1997, the American astronaut Kalpana Chawla (1962-2003) became the first Indian-born woman to travel into space. Chawla served on two missions aboard the United States space shuttle Columbia as a mission specialist and robotic arm operator.

Chawla was born on March 17, 1962, in Karnal, northern India. Karnal was part of the state of Punjab at that time. Today, it is part of the state of Haryana. She graduated from the Punjab Engineering College in 1982. That same year, she immigrated to the United States. In 1984, she earned a master’s degree from the University of Texas in Austin. She married Jean-Pierre Harrison, an aviation teacher and author, in 1983. She received her doctorate in aerospace engineering from the University of Colorado at Boulder in 1988. She then went to work at the National Aeronautics and Space Administration (NASA). In 1994, she was selected for training as an astronaut candidate.

In 1997, Chawla flew her first mission on the shuttle Columbia. She was the second person of Indian descent to travel in space, following the Indian-born cosmonaut Rakesh Sharma, who traveled on a Soviet Soyuz spacecraft in 1984. Chawla’s duties involved conducting experiments in microgravity, sometimes called zero gravity or weightlessness, and launching a satellite using the shuttle’s robotic arm. Her second mission was on the same shuttle in 2003. However, on Feb. 1, 2003, as the Columbia was returning to Earth after the 16-day mission, the spacecraft broke apart high over Texas. Chawla and six other crew members were killed.

Chawla received many honors for her work in space. They include the Congressional Space Medal of Honor, the NASA Space Flight Medal, and the NASA Distinguished Service Medal. In addition, an asteroid that orbits the sun between Mars and Jupiter is named the 51826 Kalpanachawla in her honor.

An Elysia marginata, a species of sea slug, is seen after shedding its body in an act of self-decapitation.
Credit: © Sayaka Mitoh

What’s slimy, shell-less, and can remove its own head?

A sea slug!

New research from Japan suggests that sea slugs of two closely related species—Elysia marginata and Elysia atroviridis—amputate (cut off) their own heads to grow new bodies. This act of self-amputation is an example of autotomy.

The decapitation is not for beauty reasons. A sea slug doesn’t think, “How about I switch things up? I want an oval-shaped body, rather than a tubelike one.” Instead, the researchers suspect that a sea slug nixes its noggin when its body becomes infected with a parasite. A parasite is a living thing that feeds off another living thing, called a host.

Not all sea slugs in the experiment cut off their heads. (But, to make up the difference, some slugs cut off their heads twice!) The headless bodies stayed alive for as long as months before decomposing (rotting). But even more surprisingly, the heads remained alive, eating and growing new tissue until they developed entirely new, parasite-free bodies.

For most of the sea slugs, the entire process of growing new tissue took less than a month. The head wounds healed in one day. Such organs as the heart took about one week to regenerate.

Although it is a major feat to grow an entirely new body in three weeks, sea slugs don’t need to grow too much. Most sea slugs are small, measuring less than 1 inch (2.5 centimeters) long. However, many kinds grow much larger. One group of sea slugs, called sea hares, has several large species, including one that can reach more than 2 feet (60 centimeters) in length. And although we’re just guessing, it would probably take more than a month to grow 2 feet of sea hare.

Sea slugs are not the first members of the animal kingdom to commit autotomy in self-defense. If a gecko is attacked, it can distract an enemy by waving its tail. When the enemy attacks the tail, the tail breaks off but keeps wriggling. While the enemy holds the tail, the gecko runs away. It soon grows a new tail. Starfish also practice autotomy. If grabbed, many starfish can drop off arms in order to defend themselves. They can then regenerate new arms to replace the old ones. If a starfish is cut into two or more pieces, each piece may become a new animal, as long as it contains a portion of the animal’s central disk.

The sea slug-studying scientists believe that understanding the growth process of sea slugs—as well as other animals—could lead to advances that enable people to regrow and replace damaged tissue, a field called regenerative medicine.