The scientist behind Paul the sheephead

Meet Dr. Becca Selden, the scientist behind Paul.

Dr. Becca Selden loves being a scientist. She spends a lot of her brain energy thinking about predators and prey.  Becca was curious about what happens to fish as their body sizes change. Body size is very important to fish: it controls what prey they can eat, and what predators can eat them! In some parts of the ocean, people have fished out most of the large fish, changing how predators and prey interact with each other.

Becca wanted to know how the size of predators (sheepshead fish) changed when the size of prey (sea urchins) changed.  To figure this out, she created an experiment in the Channel Islands of California, where sheepshead fish live in

Here are sheepshead choosing the urchins they want to eat in a quadrat. The quadrat is a big square made of white poles.

kelp forests. There were some areas around the island where people weren’t allowed to fish, called Marine Reserves. Pumpernickel, where Cher and Emi ended up was a marine reserve, and that’s why there were so many other big fish there. Becca tested what prey sheepshead liked to eat when they lived in marine reserves. She also tested what they could eat when they lived in other places around the islands that weren’t protected from fishing. To test the fish,  she put out different sized urchins in a quadrat, like putting a bunch of food out on a table. Then she watched what different sized sheepshead ate.

Becca discovered that until sheepshead get bigger than a half a foot long, they  don’t eat urchins. She also found that smaller sheepshead can only eat smaller urchins. In marine reserves where all the big sheepshead have been fished by people, this means the smaller sheepshead left behind can’t each the big urchins. Urchins eat the kelp forests where sheepshead live, so if predators like big sheepshead don’t eat them, urchins will eat too much kelp and destroy the forest.

A fish in Becca’s experiment, snacking on an urchin. Yum! That’s a good dinner.


predator: an animal that eats other animals

prey: an animal that is eaten by other animals

Channel Islands: islands off the coast of Southern California that are home to many kelp forests and the animals that live in kelp forests

Marine Reserves: an area of the ocean where fish is either not allowed, or limited to protect the ecosystem

quadrat: a portable square grid that makes a border around ground where scientists do experiments

Paul the sheephead finally finds a good dinner

Here’s a sheephead fish like Paul, swimming through a kelp forest. Can you think of why fish might like to live in kelp forests?

Paul the sheephead is used to the other fish teasing him about the way he looks. He is a pretty funny looking fish, even by fish standards. He has a big white chin and pointy teeth. He likes to snack on little crabs and mussels, so his big pointy teeth come in handy when he’s hungry. And right now, Paul is hungry.

“If only there was somethings to eat other than just mussels and little crabs,” he sighed, complaining to his friend Emi.
Emi only nodded jokingly to a fish hook lurking nearby, “There’s a pretty yummy looking squid here if you want to try something new!”
“Yeah, right!” Paul giggled, and for a moment he forgot he was hungry. He loved that about his best friend: Emi always knew how to make him laugh. Other fish friends were hard to come by in their kelp forrest. A lot of fish were scooped up by sneaky fishing hooks, and of the few sheepheads left, most of them are much younger and smaller than Paul. He is a young, and he is only about a foot long. (That’s a lot bigger than a goldfish, but when Paul grows up, he could be almost 3 feet long!)

Paul and Emi lived their whole lives in the kelp forrest around Catalina, an island off the coast of what the humans called “California”. It wasn’t too bad of a life, as long as you were careful to stay away from all of the fishing hooks.

Look how big this sheephead’s jaw is! Are you surprised they can chomp on hard things like crabs, urchins, and mussels?

And the big predatory fish. At night, Paul and Emi would hide in a crevice and use the mucous from their skin to make a sleeping bag. The protective mucous sleeping bag meant the predators hunting in the night couldn’t smell them. Sure, the other fish also made fun of them for their “boogie bags”, but Paul had decided long ago that it was better to be laughed at than to be a midnight snack. If the nights were scary, the mornings were lovely because the kelp forest came alive at dawn. Paul loved waking up to the sun beams dancing through the water from the surface. The serene way the enormous kelp fronds undulated with the surging water made her want to dance too.

After their laugh, Paul and Emi darted around in the dense kelp, playing hide and seek. Emi was a little smaller than Paul, so she was a good hider. After playing for a little bit, Paul’s hunger came back stronger than ever. But so did an idea…
“What about the other kelp forests? Maybe there’s somewhere else we can look for food.” Paul tentatively suggested. He knew there were other kelp forests around Catalina, but he’d never been.
Emi’s eyes lit up at the suggestion, “That’s a great idea! Let’s try to find another forest.” That was Emi, always up for an adventure. “It’s still early in the day, we can leave right away.” And with that, Paul and Emi started out southwards.
By the afternoon, they stumbled upon a vast kelp forest. It made their home forest look downright dinky by comparison! Here, fish bigger than Paul and Emi had ever seen moved effortlessly through the dense kelp fronds.
“Where are we?” Paul exclaimed breathlessly. From somewhere behind them, a bellowing voice answered,
Can you see something in this photo that the sheephead might want to eat?

“Why, this is Pumpernickel kelp forrest!” Paul and Emi turned and were amazed to see a huge fish, who looked just like them! He was a sheephead too, with a big white chin, and pointy teeth! As he looked closer around her, Paul suddenly noticed that there were a lot of other sheepheads here! Most of them were even bigger than him!

“This place is incredible!” said Emi, “There are so many fish, and so much kelp.”
“That’s because this is a marine reserve,” the big fish answered “Look around, you won’t see any hooks. That’s because fishing isn’t allowed here so fish can grow bigger and there are more of them.”
Paul looked around in amazement, but he had only one thing on his mind:
“Do you know of anything good to eat around here?” He asked
“Have a purple urchin!” the big fish suggested, gesturing towards a few in a nearby crevice.
“An urchin?” Paul exclaimed, “I’ve never eaten an urchin before!” But as he looked around again, Paul noticed that a lot of the bigger sheephead were hunting in crevices and snacking on urchins. He tried a bit, and realized that his pointy teeth were great for prying the urchin out of the crevice. And his big chin meant he had a strong jaw, perfect for crunching into an urchin. Finally, Paul didn’t feel like a funny looking fish anymore. He felt right at home, with a happy full belly. It was about time.


It may look hard to chew to you, but this urchin is a delectable dinner for Paul!

Lori la lori: Está bien ser un débil nadador

Hasta ella había visto la luz azul y brillante del sol en el dia que ella eclosionó, el

¿Puedes ver a la mamá y papá gobio quien viven en esta esponja de tubo amarillo? Indicación: ¡Están en el tubo central!

único color que ella conocía fue amarrillo. Esta Gobio Neón se llamaba Lori. Lori pasaba sus primeros 7 días de su incubación dentro de una esponja tubular y amarrilla. Frecuentemente, esto solo color había interrumpido por un vaho de azul grisáceo. Era su papá, pero ella no lo sabía entonces.  Por los 7 siguiente días que ella y sus hermanos eran huevos,  su padre a hacer paf encima de ellos, abanicándose el agua delicadamente sobre ellos con sus aletitas.

Pero ahora, mientras emergía de su saco de huevo en el azul deslumbrante, sus ojos estaban abrumados por los colores brillantes. “Guau!”, pensó ella a si misma. Sus ojos claramente eran el parte mas grande de su cuerpo pequeñito, pero de algún modo no parecía lo suficientemente grande para asimilar el arcoiris de peces afuera de su esponja tubular. Los peces estaban bailando con altibajos, comiendo piezas de comida. Algunos peces llamativos incluso habían estado coqueteando por sus baila Tango anhelante. “CUIDADO!” Lori escuchó el sonido penetrante por detrás, mientras otra larvita (pero un poquito mas grande) pasaba rápidamente. Lori se caía en su estela. Cuando levantó la vista, ella vio a la damiselita, dando vueltas alrededor de ella.

“¡Ay caray!”, se burló la larvita. “Apartase del camino…” Lori no dijo nada, y de repente, se dio cuenta que estaba flotando con la corriente. Franticamente, ella se movía sus aletas. Se adelantó un poco antes de que la corriente la domino,

“¡¿A donde debería ir?!” dijo la Lori a la damiselita, desesperadamente.

“Como podría saber?” gritó a la Lori, sin compasión. “¡Vuelve a tu casa, busca algo para comer y ponte peligro! ¡No me importa!” Y de repente, se desapareció.

Tan pronto como se fue, Lori se empeció sentir expuesta y indefensa. Ella puso todo su esfuerzo que pudo para nadar contra la corriente, pero aún así se sintió flotando a lo largo de la cresta del arrecife.

“¡No quiero que me coman!”, pensó ella en un pánico, “¡Tengo que encontrar un lugar para esconderme!”

De repente, la escena de peces ocupados en el arrecife se pareció mal acogido. Se dio cuenta de que haría un sabroso aperitivo.

Lori buscó refugio, con los ojos abiertos de desesperación. En el otro lado de la cresta del arrecife, vio con tema una profunda extensión azul de océano abierto. Eso parecía espantoso! No podía imaginar a los grandes peces que querían vivir en ese vacío imponente.

Esto es lo que Lori se verá cuando crezca. ¿Ves la línea bastante azul en su nariz? Así es como se puede saber que su especie es Elacatinus lori, también conocida como la Gobio Línea de Hocico.

La Lori miró abajo y vio una grieta pequeñita en el coral. Parecía el escondite perfecto para un bebé Gobio. Nadó con aletas frenéticas para escapar del arrecife ocupado. Ella estaba frequentamente agotada, pero por suerte la grietita estaba cerca. Se descansó entre unos granos de arena, su cuerpo transparente y pequeño desapareció perfectamente de los ojos hambrientos.

Lori se tranquilizó por el silencio de su escondite, y sintió que su corazón pequeño pulsaba lentamente. Ella reflexionó sobre su poco tiempo en la cresta del arrecife. ¿Por qué aquella damiselita era tan rápidamente y fuertemente, mientras que la Lori tenía que trabajar tan duro sólo para nadar un poquito?

“¡Oye! ¡Me alegro de que viniste! Lori oyó una voz tan pequeña como la suya, a sólo unos centímetros de ella en la arena. Se volvió a la voz amistosa y vio una larvita con ojos penqueñitos, con aletitas como la suya. Era otro bebé Gobio, como la Lori! Lori estaba abrumada de alivio.

“¡Estoy tan contenta de verte”! exclamó, “Pensé que era el único pez que no podía nadar allí, todo el mundo es tan rápido!”

“¡Por supuesto que no!” dijo la larva amigable, “¡Eres un Gobio Neón! Los gobios de neón son lentos. Pero cuando somos lo suficientemente grandes, nadamos a una nueva esponja de tubo amarillo la que es nuestra. Sólo necesitamos más tiempo que las otras larvitas.

Lori fue consolada por las palabras del Gobio. ¡Entonces ella no era una mala nadadora después de todo! Sólo un tipo diferente de nadador! A ella le gustaba ese pensamiento. Lori se descansó en sus granos de arena con su nuevo amigo. Un día, encontrarían sus propias esponjas. Pero por ahora, Lori estaba feliz de merendar el plancton que podía encontrar, y crecerse para poder encontrar su propia esponja de tubo.


Fren falls in love

Fren loved breakfast time in the morning. The early light filtered through the water, illuminating all the teensy zooplankton who had come out under the

Here is a sea anemone with the clownfish who live in it. See the two biggest fish? They are the mom and dad. The smaller fish aren’t their kids, they are other clownfish who are waiting for a date with the only female clownfish.

cover of darkness to find their dinner. Fren and his buddy Mel would dart around like rockets, picking out the stragglers who hadn’t yet made it to hiding from the daylight, or who had been captured by the anemone’s arms. Mel was a fast hunter, but Fren was faster. That’s how Fren had grown up to be the third largest clown in his home.

He lived in an itsy-bitsy anemone in a tiny lagoon off the coast of the small country of Papua New Guinea. Of course, Fren didn’t know he lived in a lagoon. And he certainly didn’t know what a “Papua New Guinea” was. If a teacher had quizzed him on what a “Papua New Guinea” was he would most likely answer that it was a kind of anemone like the one he lived in. Fren would be wrong. But Fren knew what “anemone” meant, because he lived in one! A sea anemone was an animal that lived in the ocean, but looked like an underwater bush, with wiggly polyps instead of branches, and a big sticky foot instead of roots.

Life as a clownfish is different than for other fish in the sea. Big tuna cruise carelessly in the open ocean, silver herring live in shoals that move gracefully as if one beautiful mega fish. But clownfish never leave the anemones where they start out as new recruits, kind of like a fish teenager. Clowns are terrible swimmers. Outside of their home anemones, they are an easy and slow moving tasty morsel. So once Fren found his home as a recruit, he planned to stay forever.

“Hey Fren!” called Mel with a hearty laugh, “Get your head out of the surface water, I’m beating you for once! What’s got you so distracted anyway?”

This morning, Fren found himself drifting between day dreams more than usual. He was imaging watching the sun rise in a bath of red, orange, and blue water with his true love: Ocella.

Mel groaned as he realized this.

“Ugh, not Ocella again. Give it up already, she’s with Percy!”

Fren blushed. “I can’t help it! “ he exclaimed, “She is a magical clownfish,

Look at this pair of clownfish in their home anemone! This mom and dad live in an anemone because it helps them avoid being eaten.

completely different from all the others. I swear she is more beautiful than an angel fish. It’s like only Ocella knows the only right way to swim, to breathe, to laugh, or to smile. And best of all, she is so smart and strong. I wish I could talk to her every hour of the day!”

Mel rolled his eyes. But he knew his friend was sincere. Everything Ocella did mesmerized Fren. He knew he wanted to spend the rest of his life with her from the moment he first spoke to her. But there was one problem. Ocella was the biggest clown in the anemone, which meant she was already dating another clown, Percy. Fren didn’t like Percy one bit! Percy was a bully, always pushing around the smaller clowns in the anemone because he was the biggest male. Even Ocella didn’t like him. She was kind, and loathed how mean Percy was to the smaller clowns.

Suddenly, Fren snapped out of his day dreams to feel someone shove him roughly.

“Hey!” he shouted as he regained his balance, “Watch it, you almost pushed me out of the anemone!”

When he turned around, he found him face to face with Percy. Percy was huge, and he always had a scowl distorting his face. But Fren was big too, and almost as big as Percy now.

“If only I did. I’m sick of seeing your face around here,” he snarled “I’d love to push you out of here!”

The commotion was starting to draw a crowd, and from the back of the anemone, Ocella emerged. She looked at Fren apologetically. She knew how mean Percy could be.

“Enough Percy, we don’t shove other clowns around in this anemone. I won’t tolerate this behavior any longer. I won’t warn you again!”

Fren saw the anger in her eyes. Ocella was a kind clown, but she was formidable too. Percy snarled at her,

“You can’t tell me what to do, I’m the biggest male here, not you! And I’m in charge.” He faced Fren venomously, “I’m sick of this clown. I want you gone, Fren.”

“Give it a rest Percy, we’re all sick of you bullying us!” shouted Mel bravely, moving to Fren’s side.

And just like that, Percy lost it. Fren’s little heart beat rapidly as he watched Percy dart at Mel in slow motion. Percy’s eyes were livid, his fins waving aggressively. He was going to push Mel out of the anemone! In the background, he saw Ocella move helplessly to stop him, terrified for Mel. No clowns ever survived eviction from the anemone, it was too dangerous out there in the open ocean. In an instant, Fren knew what he had to do.

Mel cowered in fear as Percy moved to strike him like lightening, but Fren was faster, and Fren was almost as big as Percy. He shoved Percy hard away from Mel, saving his friend in just the nick of time. But he didn’t realize how strong he was, and he saw Percy’s angry face disappear as he was lost through the sheltering arms of their anemone, into the outside blue.

After a shocked silence, all of the clowns in the anemone burst into cheers.

Mel hugged Fren lovingly,

“Thanks buddy! I really thought I was a goner there!”

“I’m just happy you’re safe, “ sighed Fren as he embraced his friend. He was relieved.

Silence fell on the anemone, and Fren looked up to see Ocella moving towards him. Suddenly, he realized he was the biggest male in the anemone with Percy gone… that meant he could finally ask Ocella on a date!

But she beat him to it.

“Thanks for standing up to Percy, Fren. It was brave of you to save your friend from such an awful bully. I’m glad you did. Now, our anemone can be filled with happy, kind clowns. No more intimidation.” she paused, and blushed, “Maybe you’d like to hunt breakfast together tomorrow? The sunrise looks beautiful through the water on the eastern side of the anemone.”

In the background Mel rolled his eyes, but smiled, at his friend.

“That would be a dream come true.” Fren said, and he felt his heart warm with happiness.


Want to learn more about larval swimming research?

Scientists used to think that when baby fish (called larvae) hatched, they

This is what lori looked like when she was only a 10 day old larva. Can you see her swim bladder? Because she is a larva, she is transparent and you can see inside of her!

floated in the plankton to wherever currents take them. Recently, scientists have actually measured how far larvae disperse, and it turns out, they almost never settle far from home! The scientists who did this research began to wonder, maybe larvae are really strong swimmers. If this was true, then larvae could fight the currents so they stayed close to their home reef, or could return after being carried away by currents.

The scientists tested this by putting larvae on fish treadmills, called flumes.

This is a flume, like a treadmill for fish. The fish goes inside the rectangular chamber, as swims as water flows through.

They collected Elacatinus lori larvae as they hatched on the reef in Belize, Central America, and raised them in a wet laboratory on the island of South Water Caye (put in picture of lab). As the larvae developed, scientists put them in the flume and measured how long they could swim at different water current speeds. They found that E. lori larvae actually can’t swim long at all! When scientists tested larvae at speeds close to the current speeds on the reef, larvae can’t swim longer than a few minutes. What a discovery!

Here is where scientists did the research on gobies in Belize. Do you know where Belize is?

Now the scientists are wondering how these tiny larvae, who can barely swim, are settling so close to their home reefs. Stay tuned as scientists test their next question: maybe these larvae are skilled navigators? This summer the scientists will test the orientation abilities of larvae, as nobody before ever has. Eventually, their research will help answer the question of how larvae disperse. Once we know that, we can make marine protected areas that keep of our fish and our oceans healthy.

Lori the lori: it’s okay to be a bad swimmer

Can you see the mom and dad goby who live in this yellow tube sponge? Hint: They’re in the middle tube!

Until she saw the brilliant blue light of the sun above her on the day she hatched, the only color Lori the Neon Goby knew was yellow. She had spent

But now, as she emerged from her egg sack into the dazzling blue, her eyes were overwhelmed by a flurry of bright colors.

“Wow!” Lori thought to herself in amazement.

Her eyes were by far the biggest part of her teensy tiny body, but they didn’t seem big enough to take in the fanciful rainbow of different fish outside of her tube sponge. The brilliant fish were dancing up and down in the water, nipping up little morsels of food. Some flashy fish were even flirting with each other in an eager tango.

“WATCH OUT!” Lori heard the high pitched shout from behind her as another tiny larva, but slightly bigger than her, buzzed by in a mad dash. Lori tumbled in her wake. When she looked up, she saw the damselfish baby, darting around her in circles.

“Jeez Louise!” the larva scoffed, “Either get moving or get out of the way. Some fish are trying to go somewhere…”

Lori said nothing, and noticed that she was simply drifting along with the current. She beat her little fins frantically, lurching forward only a small amount before she felt the current overpower her.

“Where am I supposed to go?!” she shouted desperately at the damselfish larva and sprinted a little farther in the other fish’s direction.

“How should I know?” she hollered back at Lori unsympathetically, “Go back home, find some food, get eaten for all I care!” with that, she zoomed away as fast as she had appeared.

Once she left, Lori began to feel exposed and helpless. She put all the effort she could to swim against the current, but still she felt herself drifting along the reef crest.

“I don’t want to get eaten!” she thought in a panic, “I’ve got to find somewhere to hide!”

Suddenly the plethora of busy fish on the reef seemed less welcoming. She realized that she would make a tasty little snack just like the other morsels the fish were picking out of the water column.

Lori looked around for shelter, her eyes wide with desperation. On the far side of the reef crest, she saw a deep blue expanse of foreboding open ocean. That seemed scary! She couldn’t imagine the big fish that would want to live in that imposing emptiness.

Lori looked down and saw a small crevice in the coral. It seemed like the perfect hiding place for a baby goby. She swam with frenzied fins to escape the busy reef. She was quickly exhausted, but luckily the little nook was close. She settled in between some grains of sand, her teensy transparent body disappearing perfectly from hungry eyes.

This is what Lori will look like when she grows up. See the pretty blue line on her nose? That’s how you can tell her species is Elacatinus lori, otherwise known as the Line Snout Goby!

Lori was soothed by the silence of her hiding spot, and she felt her wee little heart beat slowing down. She reflected on her short time on the reef crest. Why was that little damselfish so fast and strong, while Lori had to work so hard just to swim an eensy-weensy bit?

“Hey! I’m glad you made it!” Lori heard a voice as small as her own, only a few inches away from her in the sand. She turned to the friendly voice, and saw a wide eyed, scrawny larva with little fins just like hers. It was another Neon Goby baby, just like Lori! Lori was overwhelmed with relief.

“I’m so glad to see you!” She exclaimed. “I thought I was the only fish who couldn’t swim up there, everyone else was so fast!”

“Of course not!” said the welcoming larva, “You’re a Neon Goby! We Neon Gobies are slow. But when we are big enough, we swim to a new yellow tube sponge of our own. It just takes us longer than the other larvae.”

Lori was comforted by the kind Goby’s words. So she wasn’t a bad swimmer after all! Just a different kind of swimmer! She liked that thought. Lori settled into her sand grains with her new friend. One day, they would find their own sponges. But for now, Lori was happy to nibble on the plankton she could find, and get bigger so she could find a tube sponge of her own.