Connect with us

The Conversation

What happens to the ocean if we take out all the fish? A marine ecologist explains the complex roles fish play in their ecosystem

Published

on

What happens to the ocean if we take out all the fish? A marine ecologist explains the complex roles fish play in their ecosystem

Fish swim in a reef at Pearl and Hermes Atoll in the Northwestern Hawaiian Islands.
AP Photo/Jacob Asher

Kory Evans, Rice University

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to curiouskidsus@theconversation.com.


What would happen to the ocean if we took out all the fish? – Reny, age 12


The ocean is massive and covers most of the surface of our planet. In addition to its size, it’s packed with life, ranging from an astounding diversity of plants, microbes, worms, corals and crabs to squids, whales and, yes, even fish. The ocean is full of fish, so much so that they make up the second-largest amount of all carbon – the material that makes up living things – in the entire animal kingdom. They’re just behind the group containing insects and crustaceans.

Most people only interact with the ocean from a beach or in a boat, so it can be hard to wrap your head around how many fish there really are. But the ocean is swarming with them, from its surface to its depths.

These fish also come in all kinds of shapes and sizes, ranging from the tiny sardines, guppies and blennies that you might see on a coral reef to massive tunas and whale sharks that you might find out in the open ocean.

These fish perform all kinds of roles in their ecosystems that support the lives of other organisms around them. If they disappeared one day, the ocean would look very different.

School of slopehead parrotfish.
NOAA, Kevin Lino

I’m a scientist who studies fish, their diversity and all the ways they contribute to ocean environments.

Fish as food

Fish play important roles as both predators and prey in ocean ecosystems. Thousands of species throughout the ocean and terrestrial ecosystems rely on fish for food – including people.

In coral reef ecosystems, small fish are eaten by larger fish and other marine animals. This means the little fish form the base of the food web – they provide energy to the bigger fish and other creatures.

Conceptual food web of a coral reef ecosystem identifying key functional groups.
Links between different species of coral reef animals.
Global Change Biology, Rogers et al., 2015

Outside of the water, many birds, mammals and reptiles eat fish and rely on them as an essential source of protein.

Even land plants can benefit from the presence of fish. On the western coast of the United States, salmon returning to small streams after spending several years at sea function as a conveyor belt of nutrients. The salmon feed not only animals that catch them, like bears, but also the plants that border the streams. Studies have shown that some plants get 70% of their nitrogen from salmon that die on or near the river banks.

Humans also depend on fish as a food source. Fish and other seafood products are an important protein source for nearly 3 billion people. Human populations have been eating and following fish around the world for thousands of years.

Fish maintain habitats

Fish are also more than just food. As fish themselves forage for food, they can create and maintain important habitats for other organisms. In coral reef ecosystems, plant-eating fish control the growth of algae by constantly grazing it down. Without the help of these herbivores, or plant-eating fish, the algae would rapidly grow and smother the coral, effectively killing it.

One type of herbivorous fish, the parrotfish, feeds directly on the corals. At first, this may seem bad for the corals, but the grazing done by parrotfish can actually increase a coral colony’s rate of growth. And the poop – yes, the poop – from parrotfish has been shown to be particularly nutritious for corals. Parrotfish poop also forms part of the beautiful white sand beaches that you may have enjoyed on a family vacation.

Other fish create habitats for other animals and influence their environment by disturbing sand while they feed. By moving the sand around, they’re exposing tiny organisms hiding in the sand, which other animals can eat.

YouTube video
Some fish sift through sand to find their food. That creates more opportunities for other creatures to find food in the sand.

Despite the fact that many types of fish are confined to the ocean, their presence can be felt across many habitats. They can directly and indirectly affect the lives of the organisms that depend on them for food and shelter. Without fish, Earth would gradually lose its beautiful white sand beaches, the coral reef ecosystems would be overgrown with algae, lots of people would run out of food to eat, and we would lose some of the planet’s most fascinating creatures.


Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to CuriousKidsUS@theconversation.com. Please tell us your name, age and the city where you live.

And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.The Conversation

Kory Evans, Assistant Professor of BioSciences, Rice University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The Conversation

Supreme Court considers whether states may prevent people covered by Medicaid from choosing Planned Parenthood as their health care provider

Published

on

theconversation.com – Naomi Cahn, Professor of Law, University of Virginia – 2025-04-02 17:04:00

Planned Parenthood clinics, like this one in Los Angeles, are located across the United States.
Patrick T. Fallon/AFP via Getty Images

Naomi Cahn, University of Virginia and Sonia Suter, George Washington University

Having the freedom to choose your own health care provider is something many Americans take for granted. But the Supreme Court is weighing whether people who rely on Medicaid for their health insurance have that right, and if they do – is it enforceable by law?

That’s the key question at the heart of a case, Medina v. Planned Parenthood South Atlantic, that began during President Donald Trump’s first term in office.

“There’s a right, and the right is the right to choose your doctor,” said Justice Elena Kagan on April 2, 2025, during oral arguments on the case. John J. Bursch, the Alliance Defending Freedom lawyer who is representing South Carolina Director of Health and Human Services Eunice Medina, countered that none of the words in the underlying statute had what he called a “rights-creating pedigree.”

As law professors who teach courses about health and poverty law as well as reproductive justice, we think this case could affect access to health care for 72 million Americans, including low-income people and their children and people with disabilities.

Excluding Planned Parenthood

The case started with Julie Edwards, who is enrolled in Medicaid and lives in South Carolina. After she struggled to get contraceptive services, she was able to receive care from a Planned Parenthood South Atlantic clinic in Columbia, South Carolina.

Planned Parenthood, an array of nonprofits with roots that date back more than a century, is among the nation’s top providers of reproductive services. It operates two clinics in South Carolina, where Medicaid patients can get physical exams, cancer screenings, contraception and other services. It also provides same-day appointments and keeps long hours.

In July 2018, however, South Carolina Gov. Henry McMaster issued an executive order that barred health care providers in South Carolina that offer abortions from reimbursement through Medicaid.

That meant Planned Parenthood, a longtime target of conservatives’ ire, would no longer be reimbursed for any type of care for Medicaid patients, preventing Edwards from transferring all her gynecological care to that office as she had hoped to do.

Planned Parenthood and Edwards sued South Carolina, claiming that the state was violating the federal Medicare and Medicaid Act, which Congress passed in 1965, by not letting Edwards obtain care from the provider of her choice.

A ‘free-choice-of-provider’ requirement

Medicaid operates as a partnership between the federal government and the states. Congress passed the law that led to its creation based on its power under the Constitution’s spending clause, which allows Congress to subject federal funds to certain requirements.

Two years later, due to concerns that states were restricting which providers Medicaid recipients could choose, Congress added a “free-choice-of-provider” requirement to the program. It states that people enrolled in Medicaid “may obtain such assistance from any institution, agency, community pharmacy, or person, qualified to perform the service or services required.”

This provision is at the core of this case. At issue is whether a civil rights statute provides a right for Medicaid beneficiaries to sue a state when their federal rights have been violated. Known as Section 1983, it was enacted in 1871.

Bursch, backed by the Trump administration, argued before the court that the absence of words like “right” in the Medicaid provision that requires states to provide a free choice of provider means that neither Edwards nor Planned Parenthood has the authority to file a lawsuit to enforce this aspect of the Medicaid statute.

Nicole A. Saharsky, Planned Parenthood’s lawyer, argued that the creation of a right shouldn’t depend on “some kind of magic words test.” Instead, she said it was clear that the Medicaid statute created “a right to choose their own doctor” because “it’s mandatory” that the state provide this option to everyone with health insurance through Medicaid.

She also emphasized that Congress wanted to protect “an intensely personal right” to be able “to choose your doctor, the person that you see when you’re at your most vulnerable, facing … some of the most significant … challenges to your life and your health.”

Restricting Medicaid funds

Through a federal law known as the Hyde Amendment, Medicaid cannot reimburse health care providers for the cost of abortions, with a few exceptions: when a patient’s life is at risk or her pregnancy is due to rape or incest. Some states do cover abortion when their laws allow it, without using any federal funds.

Therefore, Planned Parenthood only gets federal Medicaid funds for abortions in those limited circumstances.

McMaster explained that he removed “abortion clinics,” including Planned Parenthood, from the South Carolina Medicaid Program because he didn’t want state funds to indirectly subsidize abortions.

South Carolina “decided that Planned Parenthood was unqualified for many reasons, chiefly because they’re the nation’s largest abortion provider,” Bursch told the Supreme Court.

But only 3% of Planned Parenthood’s services nationwide last year were related to abortion. Its most common service is testing for sexually transmitted diseases. Across the nation, Planned Parenthood provides health care to more than 2 million patients per year, most of whom have low incomes.

Man with gray hair in a suit and red tie speaks at a podium.
South Carolina Gov. Henry McMaster speaks to a crowd during an election night party on Nov. 3, 2020, in Columbia.
Photo by Sean Rayford/Getty Images

Section 1983

Because the Medicaid statute itself does not allow an individual to sue, Edwards and Planned Parenthood are relying on Section 1983.

Lower courts have repeatedly upheld that the Medicaid statute provides Edwards with the right to obtain Medicaid-funded health care at her local Planned Parenthood clinic.

And the Supreme Court has long recognized that Section 1983 protects an individual’s ability to sue when their rights under a federal statute have been violated.

In 2023, for example, the court found such a right under the Medicaid Nursing Home Reform Act. The court held that Section 1983 confers the right to sue when a statute’s provisions “unambiguously confer individual federal rights.”

Consequences beyond South Carolina

The court’s decision in the Medina case on whether Medicaid patients can choose their own health care provider could have consequences far beyond South Carolina. Arkansas, Missouri and Texas have already barred Planned Parenthood from getting reimbursed by Medicaid for any kind of health care. More states could follow suit.

In addition, given Planned Parenthood’s role in providing expansive contraceptive care, disqualifying it from Medicaid could harm access to health care and increase the already-high unintended pregnancy rate in America.

The ramifications, likewise, could extend beyond the finances of Planned Parenthood.

If the court rules in South Carolina’s favor, states could also try to exclude providers based on other characteristics, such as whether their employees belong to unions or if they provide their patients with gender-affirming care, further restricting patients’ choices.

Or, as Kagan observed, states could go the opposite direction and exclude providers that don’t provide abortions and so forth. What’s really at stake, she said, is whether a patient is “entitled to see” the provider they choose regardless of what their state happens to “think about contraception or abortion or gender transition treatment.”

If the Supreme Court rules that Edwards does have a right to get health care at a Planned Parenthood clinic, the controversy would not be over. The lower courts would then have to decide whether South Carolina appropriately removed Planned Parenthood from Medicaid as an “unqualified provider.”

And if the Supreme Court rules in favor of South Carolina, then Planned Parenthood could still sue South Carolina over its decision to find them to be unqualified.The Conversation

Naomi Cahn, Professor of Law, University of Virginia and Sonia Suter, Professor of Law, George Washington University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More

The post Supreme Court considers whether states may prevent people covered by Medicaid from choosing Planned Parenthood as their health care provider appeared first on theconversation.com

Continue Reading

The Conversation

23andMe is potentially selling more than just genetic data – the personal survey info it collected is just as much a privacy problem

Published

on

theconversation.com – Kayte Spector-Bagdady, Associate Professor of Obstetrics and Gynecology, University of Michigan – 2025-04-02 07:48:00

For companies like 23andMe, consumers are as much the product as the DNA test kits.
Veronika Oliinyk/iStock via Getty Images Plus

Kayte Spector-Bagdady, University of Michigan

As soon as the genetic testing company 23andMe filed for bankruptcy on March 23, 2025, concerns about what would happen to the personal information contained in its massive genetic and health information database were swift and widespread. A few days after, a U.S. judge ruled that the company could sell its consumer data as part of the bankruptcy.

The attorneys general of several states warned their citizens to delete their genetic data. California urged its citizens to request that 23andMe delete their data and destroy their spit samples. Michigan’s attorney general released a statement warning that “23andMe collects and stores some of the most sensitive personal information, our genetic code.”

When customers originally signed up for 23andMe, they agreed to terms and conditions and a privacy notice that allows the company to use their information for research and development as well as share their data, in aggregate, with third parties. If consumers consented to additional research, which the vast majority did, the company can additionally share their individual information with third parties. 23andMe has also been clear that if it is involved in a bankruptcy or sale of assets, consumer information might be sold or transferred.

While 23andMe has warned customers all along about everything that is currently happening, many are still surprised and concerned.

I’m a lawyer and bioethicist who has been studying direct-to-consumer genetic testing for almost a decade. Understanding what information 23andMe has been collecting, and how it might be used if sold or shared, can help clarify concerns for consumers.

What is 23andMe?

In 2007, 23andMe, named after the 23 pairs of chromosomes found in a human cell, was one of the first direct-to-consumer genetic testing companies to open in the United States. It was backed by a large investment by Google, which quickly attracted the interest of other investors, allowing 23andMe to thrive when many other direct-to-consumer genetic companies went quickly out of business.

The direct-to-consumer business model is fairly straightforward: A consumer orders a genetic test kit online, spits into a tube that comes in the mail, returns it to the company and accesses their results in an online portal. Over 15 million consumers bought 23andMe, and the vast majority consented to its research. At its peak, the company was valued at US$6 billion.

YouTube video
The fate of the trove of personal information 23andMe has gathered over the years has wide-ranging implications for consumers.

While the market initially believed in the value of 23andMe’s business model, its stock has been in decline for years, and the company owes hundreds of millions of dollars to creditors.

Reasons for this rapid decline include a decrease in the sale of test kits after a 2023 hack of almost 7 million people’s data, as well as a failure to profit enough from providing data access to other private sector companies. Lack of private interest in 23andMe data may be related to the fact that much of the information the company collects is self-reported, which is often considered less reliable than information written down by a doctor in a medical record.

What kind of data does 23andMe collect?

While the saying goes “If you’re not paying, you’re the product,” 23andMe managed to convince its consumers to both pay for AND be the product. It did this by selling genetic testing kits to consumers as well as collecting a massive amount of their valuable data.

And 23andMe collected more than just genetic data generated from consumers’ spit. Eighty-five percent of customers consented to 23andMe research, allowing their individual-level data to be used for studies. The company then collected information from survey questions about their personal health and beyond, such as drinking habits and risk tolerance.

This means that not only does 23andMe possess the genetic data of 15 million people, but it also possesses almost a billion additional data points associated with this genetic information. This makes the 23andMe dataset potentially very private – and very valuable.

At first, drug companies seemed to agree. For example, in 2018, 23andMe granted pharmaceutical company GlaxoSmithKline an exclusive license to use consented customer data to develop new drugs. GlaxoSmithKline also made a $300 million equity investment in 23andMe. When 23andMe went public in 2021, its $6 billion valuation reflected the promise of this business model.

But for over a decade, scholars, including me, have been warning that allowing 23andMe to collect and use personal data was not one that customers fully understood, or were actually comfortable with.

What should 23andMe customers worry about?

In response to current public concern about data privacy, 23andMe has stated that there will be no changes to how it stores and protects data during its bankruptcy proceedings. But once that stage is through, what exactly should customers worry about?

First, law enforcement could use genetic information in civil or criminal cases. This happened in 2018, when police used the genetic testing company GEDmatch to help identify the Golden State Killer. Police pretended they were customers looking for genealogy data and sent in an old crime scene blood spot. This allowed them to connect to known suspects with blood relatives who had given their genetic information to the company as consumers. While this was in violation of GEDmatch’s own policies, the evidence was successfully used in court.

Second, genetic information could be used to discriminate against customers if it shows that they have or are at high risk of developing a genetic disease or disorder. The federal Genetic Information Nondiscrimination Act prohibits health insurers and employers from asking about genetic information or using it to discriminate in work or health insurance decisions. It does not, however, protect against discrimination in long-term care or life insurance.

DNA sequencing results reflected off a person's glasses
Giving someone your genetic, medical and personal information gives them opportunities to exploit you.
Westend61/Getty Images

Many of the warnings from the media and attorneys general are focused on genetic information because it is unique to only one person. But direct-to-consumer genetic testing companies also retain a massive amount of personal information from the surveys consumers are asked to complete. Much of this information could be embarrassing if it were inadvertently or intentionally revealed, such as a person’s intelligence.

In the 2025 book “Careless People,” former Meta executive Sarah Wynn-Williams reported that Facebook would use indications of self-consciousness about personal appearance, such as deleting a selfie, to promote beauty products. If companies know such intimate details about a person, they could not only be used to sell products, but also potentially manipulate them over social media or the internet in ways they do not even realize. It could be used for targeted advertising or to build algorithms that exploit a person’s vulnerabilities.

I believe consumers are right to be worried about how their genetic data could be misused. But the survey data containing all sorts of other personal information are at least as much, if not more, of a privacy problem. This is particularly concerning if the data is pooled together with other information available on the internet, like a dating profile, to create a more detailed – and personal – picture of an individual.

I am deleting my own 23andMe data. In the future, I would also warn consumers against freely gifting the private sector with information about their fears, hopes, limitations and successes.

That information is valuable to more people than just you.The Conversation

Kayte Spector-Bagdady, Associate Professor of Obstetrics and Gynecology, University of Michigan

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More

The post 23andMe is potentially selling more than just genetic data – the personal survey info it collected is just as much a privacy problem appeared first on theconversation.com

Continue Reading

The Conversation

Why do dogs love to play with trash?

Published

on

theconversation.com – Nancy Dreschel, Associate Teaching Professor of Small Animal Science, Penn State – 2025-03-31 07:15:00

Dogs will be dogs.
Raul Arboleda/AFP via Getty Images

Nancy Dreschel, Penn State

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to CuriousKidsUS@theconversation.com.


Why do dogs love to play with trash? – Sarah G٫ age 11٫ Seguin٫ Texas


When I think about why dogs do something, I try to imagine what motivates them. What does a dog get out of playing with trash? As a veterinarian and a professor who teaches college students about companion animals, I believe there’s an easy answer: Garbage smells delicious and tastes good to dogs.

Dogs have an amazing sense of smell. They have 300 million receptors for smell in their noses, while humans have only 6 million. People can make use of this sniffing ability to train dogs to detect illegal drugs, explosives and endangered species, and to help locate people lost in the woods.

While you might not like how your trash smells, to your dog it is an appealing buffet brimming with apple cores, banana peels, meat scraps and stale bread. Even used napkins and paper towels are tempting to dogs, when they are smeared with and carry the smell of yesterday’s lunch.

Because dogs can find trace amounts of explosives or a person buried under 6 feet (1.8 meters) of snow after an avalanche, they are certainly capable of locating last night’s pizza crust and chicken bones in the kitchen garbage can.

Sometimes it’s hard to see what the attraction is. My Australian cattle dog mix, Sparky, loves to eat used tissues – gross, right?

Even empty cans smell inviting to dogs. Trash cans in kitchens and bathrooms are often at their nose level, too, making for easy access. Add to that the fact that if the dog got into the garbage once and found something tasty, they will likely keep searching with the hope of being rewarded again.

A dog in a bright yellow vest matching their trainer sniffs a cardboard box that appears to be cargo.
A Colombian police officer uses a drug-sniffing dog to search packages of flowers prior to export at El Dorado International Airport in Bogota on Feb. 5, 2025.
Raul Arboleda/AFP via Getty Images

Thrill of the hunt

Searching and digging around for food is natural for dogs because it provides some of the thrill of the hunt, even if they just ate and aren’t hungry.

The most successful prehistoric dogs ate the bones and scraps that humans left behind more than 10,000 years ago. Hanging around humans and their garbage was a way they could get plenty to eat. Even your pup today has some of those same old searching instincts.

While our trash has changed from the days of hunting and gathering, the discarded paper napkins, plastic wrappers and food scraps we throw away all still smell like food to dogs. And this scavenging behavior is still hardwired in our pampered pets. Although it may look to us like they’re playing, our dogs’ sniffing out and tearing things up from the trash and tossing them around mimics what their ancestors did when they tugged on and tore up an animal carcass they had found.

Many people take advantage of this instinct and use “snuffle mats” – cloth or paper where food is hidden – or puzzle feeding toys to keep their pups’ minds active. Having to hunt for and find their food helps them use their noses and sharpens their skills.

Annoying or even dangerous

While spreading trash all over the home may be natural for dogs, cleaning it up is no fun for the people they live with. And if your dog pokes its nose in a garbage can, it could be in danger. Eating plastic bags, string, chicken bones, chemicals or rotten food can cause blockages, diarrhea and poisoning. Commonly referred to as “garbage gut,” garbage poisoning can be life-threatening.

I’ve treated dogs that cut their tongues and mouths on cans or broken glass. I once performed surgery to remove a corncob from the intestines of a dog that had eaten it a month earlier. He was certainly relieved when he woke up.

How can you keep your dogs away from the trash?

It can be hard to train a dog to leave garbage alone, especially if they have found a tasty morsel or two by raiding the trash can in the past. I recommend that you invest in a garbage can with a lid closed by a latch that they can’t open. If that fails, you can put garbage – especially food scraps – out of reach in a closet, cupboard or behind a closed door.

My trash cans are all behind closed doors, and the bathroom doors are always shut, which also keeps my cat, Penny, from unrolling the toilet tissue. But that’s another story. Our kitchen trash is in a latched cupboard.

No one knows exactly what goes through dogs’ minds. And yet looking at what motivates your canine companion and how dog behaviors have evolved may help explain why these animals do the things they do.


Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to CuriousKidsUS@theconversation.com. Please tell us your name, age and the city where you live.

And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.The Conversation

Nancy Dreschel, Associate Teaching Professor of Small Animal Science, Penn State

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More

The post Why do dogs love to play with trash? appeared first on theconversation.com

Continue Reading

Trending