Animals

Animals

World Bee Day: Bees Working Together

By Posted on 7 min read 541 views

May 20th is World Bee Day! I found a really cool research article that features both honey bees and bumble bees, and I thought I’d share it to help celebrate.

By far, honey bees are the more well-known of the pollinators. These are the bees that beekeepers take care of in tall, wooden hives in a field or in their backyard. Commercial beekeepers rent their honey bee hives to farmers to pollinate food crops, as opposed to hobby beekeepers, who just let their beehives stay put and harvest honey every once in a while. Although commercial beekeepers collect and sell honey, too.

The ever-popular European or Western honey bee, Apis mellifera. Photo source: iNaturalist.
A group of honey bee hives. Photo source: Wikipedia.
Beekeepers inspecting a honey bee hive. Photo source: mnn.com.

The reason why wooden honey bee hives are so tall is because there are thousands of honey bees in a honey bee colony. They need lots of room to move around, raise baby bees into adults, and store their honey. Honey bees are used to pollinate food crops because there are many bee mouths to feed, so lots of honey bees in a hive go out to collect nectar (which the adult bees drink for energy) and pollen (which has the protein needed by baby bees to grow).

What is pollination, anyway? Pollination happens when pollen grains are moved from one part of the flower to another. When this happens, the flower can turn into fruit and create seeds, and the seeds allow new plants to grow. When a honey bee visits a flower, pollen grains stick to her, and as she moves around they can rub off onto the part of the flower that receives pollen. So in a way, bees pollinate flowers by accident!

But honey bees are not the only pollinators. Flies, butterflies, bats, hummingbirds, beetles, and moths also pollinate flowers. Some plants are even pollinated by the wind! But there are also thousands of other species of bees besides honey bees that are pollinators. One type of bee that pollinates flowers happens to be my favourite type of bee: the bumble bee!

Bombus terrestris, or the buff-tailed bumble bee, which is found in many parts of Europe. There are hundreds of species of bumble bees with different fur colours and patterns. Photo source: iNaturalist.

Why are bumble bees my favourite? Besides looking like little winged teddy bears, they are quite tough little workers. Thanks to their fuzzy coats, they can go out and forage (collect food) when it is cooler outside, and because of their bigger size they can withstand stronger winds compared to honey bees. I remember doing some research in a blueberry field and the weather turned rather chilly and windy…a storm was coming. When I looked around, all of the honey bees had hurried on home but bumble bees were still out in force, collecting food, until the first few drops of rain arrived.

If bumble bees are such good little workers, why don’t farmers use them to pollinate their crops? Well, some do. There are companies that breed bumble bees and sell them to farmers, particularly to pollinate greenhouse tomatoes (honey bees don’t pollinate tomatoes). However, the colonies of bumble bees that come from these companies often have disease, due to the factory-like conditions that they are bred in. But that’s a story for another day. (I talk more about this in my upcoming book, The Beekeepers, to be released in March 2021.) But bumble bee colonies are quite small compared to honey bee colonies: a family of bumble bees is usually around 100-200 worker bees, plus the queen. Because there are so fewer mouths to feed, only a handful of bumble bees go out to forage at any one time. So a LOT of bumble bee colonies are needed to pollinate the vast fields of food crops that exist today. And, quite simply, people have used honey bees for hundreds of years to pollinate crops, whether or not there exist better native animals out there that can do a better job.

ANYWAY…all of this is to say that even though people use honey bees to pollinate their crops, there exist multitudes of native, wild critters, such as bumble bees, that pollinate the crops, too. Like in the blueberry field I was in: the farmer was using honey bee hives, yet bumble bees that naturally lived in the area were taking advantage of the bounty, too. (Honey bees are not native to North America. They were imported from Europe hundreds of years ago.)

Which brings me to the research study: could naturally-occurring bumble bees actually help honey bees do a better job at pollinating plants?

With some crops such as sunflowers and almonds, there is evidence that when in the presence of bumble bees, honey bees performed better. Specifically, they were more likely to fly to different rows of plants rather than sticking to just one plant or plants that were close together. Flying between distant plants causes what is called cross-pollination: taking pollen from one plant and delivering it to one that is further away tends to result in better fruit. A group of scientists in Belgium decided to study this systematically in sweet cherry orchards, to see if bumble bees do in fact influence honey bees to do a better job.

The scientists chose eight sweet cherry orchards across Belgium that were in full bloom. They made sure that each orchard was surrounded by hedgerows, wildflowers, trees, forests, and/or shrubs so that there would definitely be wild bumble bees living nearby.

Sweet cherry blossoms. Photo source: iNaturalist.

In each orchard they selected blocks that were each roughly 4 metres by 5 metres. In 25-minute intervals, the scientists used a net to catch every honey bee and bumble bee that visited the cherry blossoms. They then put each bee in a tube so they could identify it, and also so that they didn’t count the same bee twice. When 25 minutes were up, they released the bees. This data allowed them to measure bumble bee abundance, which was the number of bumble bees they counted, and bumble bee richness, which was the number of different species of bumble bees they caught. They also measured honey bee abundance (the number of honey bees they caught).

At the same time as bees were being caught and identified, other scientists walked slowly up and down the rows of cherry trees. When they saw a bee visit a cherry blossom, they noted whether it was a honey bee or a bumble bee, and they followed it to see whether its next visit was to a tree in the same row or to a tree in a different row. If a bee visited trees in different rows, this meant that the cherry blossoms were being cross-pollinated, and this should result in better cherries (bigger, juicier, and overall higher quality).

What did the scientists find? It was clear that bumble bees were the superstars! Compared to honey bees, bumble bees visited around twice as many cherry blossoms and changed rows almost twice as often. But the really cool thing? When there were more bumble bees and more types of bumblebees around (that is, high bumble bee abundance and richness), the better the honey bees performed! The honey bees visited more blossoms and changed rows more often when in the presence of bumble bees. Somehow, bumble bees influenced honey bees in a positive way to get more cherry blossoms pollinated.

So, what this research tells us is that it is important to provide places for wild bumble bees to live around food crops, even if the farmers are using honey bees to pollinate their plants. Providing habitat for bumble bees is a win-win situation: the bumble bees can have a home, influencing honeybees to do their best, and in the end, we can harvest better quality food.

But how exactly did the bumble bees influence the honey bees? Were they somehow yelling at the honey bees, “C’mon, sisters! Step it up!” Were they somehow showing the honey bees how to do a better job? That’s another puzzle for another research study!

What Can You Do to Help the Bees?

This post on World Bee Day would not be complete without some tips about what you can do to help bees. Here are some suggestions:

DON’T START KEEPING HONEY BEES! Many people think that by getting a honey bee colony and keeping it in their backyard, they are somehow “helping the bees.” Sorry, but no, you are not. Honey bees are not native to North America, and they take food and space away from native bees, like bumble bees, who are trying to live in the wild. Honey bees can also introduce diseases into the wild, and can make native critters (like bumble bees) sick.

AVOID PESTICIDES. There are tons of research studies that show that pesticides harm and even kill bumble bees, honey bees, and other insects. A well-manicured lawn is a wasteland for bees and other critters anyway.

TRY THE “MESSY LOOK.” Let your yard, or parts of your yard, go wild and see what happens. Many wildflowers and weeds are actually quite pretty. And many wildflowers and weeds provide nectar and pollen for bees. Leaving piles of leaves and branches in your yard also provides a place for the bees to hibernate for the winter or escape bad weather.

TRY TO PLANT NATIVE FLOWERS. Wild bumble bees know best the types of plants that naturally grow in their area. So why not do a bit of research and find out what plants naturally grow where you live? The bees will thank you!

Reference

Eeraerts, M., Smagghe, G., & Meeus, I. (2020). Bumble bee abundance and richness improves honey bee pollination behaviour in sweet cherry. Basic and Applied Ecology, 43, 27-33. https://doi.org/10.1016/j.baae.2019.11.004

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Animals

A Good News Story: A Blue Bee is Found!

By Posted on 6 min read 652 views

I am always uplifted and filled with joy and hope when an animal that was thought to be rare or extinct or maybe was never seen before, is found in the wild. This time it is a bee! The beautiful blue calamintha bee, Osmia calaminthae. It was last seen in 2016 in a small-ish area in the Lake Wales Ridge region of Florida. And now it has been seen again!

The blue calamintha bee is a special little bee. And I say little because it is quite small: these bees are only 10-11 mm long. Not only have they been spotted within a specific area in Florida, but they also seem to feed from one particular type of flower: Ashe’s calamint. Ashe’s calamint also happens to be endangered.

The blue calamintha bee specializes in Ashe’s calamint. Photo source: Florida Museum.

The blue calamintha bee is a funny little critter when it comes to pollinating the flowers. When the bee sticks her head in the flower to suck up some nectar, she bobs her head back and forth. The hairs on her face become covered in pollen. So, when she emerges she has a face full of pollen! These bees have been found flying around with big blobs of pollen on their face. It is thought that just like some bees pack pollen into balls on their back legs in order to bring it back to their nest to feed the baby bees, perhaps blue calamintha bees carry the pollen home on their face. Maybe not the most attractive way to do things, but it could work!

Here is a blue calamintha bee feeding from Ashe’s calamint. Her head is probably getting covered in pollen. Photo source: ZooKeys journal.

Blue calamintha bees are a type of solitary bee. Unlike honey bees and bumble bees who live in hives or nests with big families, solitary bees live alone, as their name suggests. They only get together to mate, and then the female lays her eggs in a safe and secluded spot. We’re not sure where blue calamintha bees lay their eggs, but other solitary bees tend to lay their eggs in hollow stems, holes in dead logs, or existing burrows that were made by some other creature. (You know the “bee houses” you can buy in stores and online, that are made up of wooden tubes? These are for solitary bees.) After laying her eggs, the mother bee flies away–she never sees her babies. Then, after the baby bees hatch and are big enough, they fly off to live on their own and they start the cycle again.

So. Back to our good news story. These little blue calamintha bees had not been seen for four years. But then a scientist named Dr. Chase Kimmel spotted them. And not only did he find them in the areas where they were seen before, but he also saw them in six other locations up to 95 km away! That’s really good news. It could mean the population is in good enough shape that it is expanding where it lives, and it is finding good enough food and homes elsewhere.

When Dr. Kimmel saw the rare blue calamintha bees, what did he do? Well, if you watch bees you will quickly discover that they can move very fast. Even scientists have a hard time identifying a bee when it is just flying around. So, scientists have to catch them. And the way scientists identify blue calamintha bees is by looking at specific features on its head. So somehow Dr. Kimmel had to get really close.

The way Dr. Kimmel catches and examines the bees is quite clever. First, he catches the bee in a net. Then, he reaches into the net while holding a plastic bag. Once the bee is in the bag, he holds the bag closed and takes it out of the net to get a closer look. If the bee looks like an Osmia-type bee (remember the blue calamintha bee is technically Osmia calaminthae), he cuts a teeny-tiny piece off the corner of the plastic bag. When the bee crawls to the hole and tries to escape, it gets stuck. Only its head pokes out.

A blue calamintha bee poking her head out of the corner of a plastic bag. Photo source: Chase Kimmel and the Florida Museum.

“So now I have the bee in a bag with just its head sticking out,” Dr. Kimmel told me. “Then I look at its head using a hand lens and look for diagnostic characters that identify this species. Fortunately, these characters are on its face so I look at the hairs on its face and its mandibles [mouthparts] with the hand lens. If these criteria are met, then I take many photos of its face with a camera to have a record that I caught the bee.” After he takes enough photos, he opens the bag and the bee flies away, unharmed. Pretty cool!

Cutting a hole in a plastic bag that is just big enough for a small bee’s head to fit through is extremely tricky. “If the hole that I make is too big, even by 0.5 mm, the bee may escape,” said Dr. Kimmel. So, he does all of his cutting while the bag and bee are still in the net. If the bee manages to squeeze its body all the way through the hole he cut in the bag, the bee is still in the net. If that happens, he takes out the plastic bag and tries again.

After the bee flies away, there is an added bonus: pollen residue is left in the bag. “We freeze this pollen and analyze it to determine what plants the bee has been visiting,” said Dr. Kimmel. Could the bees be drinking nectar and gathering pollen from plants other than the Ashe’s calamint? Only time will tell!

One other thing Dr. Kimmel has been busy doing is placing a number of “bee condos” around the areas where the blue calamintha bee or Ashe’s calamint has been found. These bee condos have a variety of different sized holes so that Dr. Kimmel and his team can discover what kind of place blue calamintha bees like best to lay their eggs.

A nest box with different sized holes to see which ones the blue calamintha bee likes best. Photo source: Chase Kimmel and the Florida Museum.

So, why has the blue calamintha bee been so tricky to find? One clue could be that Dr. Kimmel and his team have to drive for 30-40 minutes through orange groves to reach the conservation site where the bee has been seen. Humans have converted vast areas of land into food crops, which takes habitat away from blue calamintha bees and other animals. Also, there is a chance that these food crops have been treated with pesticides which can seriously affect the health of the bees. But we need more research to be sure. Dr. Kimmel points out that this is the first time an extensive survey has been done for the little bee, so that he and his team can find out whether its population is increasing or decreasing. Also, their research will uncover what we can do to help the bee.

Dr. Kimmel is hopeful. “While the bee is still very rare and can take a long time to find it when it is present,” he said, “since we’ve found it in many new properties it gives me hope that we can act and help this bee.”

References

Kimmel, C. (May 17, 2020). Personal communication.

Kimmel, C. (May 18, 2020). Personal communication.

Rightmyer, M. G., Deyrup, M., Ascher, J. S., & Griswold, T. (2011). Osmia species (Hymenoptera, Megachilidae) from the southeastern United States with modified facial hairs: Taxonomy, host plants, and conservation status. ZooKeys, 148, 257-278. DOI: 10.3897/zookeys.148.1497

Srinivasan, N. (May 7, 2020). Florida’s rare blue bee rediscovered at Lake Wales Ridge. https://www.floridamuseum.ufl.edu/science/floridas-rare-blue-calamintha-bee-rediscovered/

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Animals

Baby Long Legs! And a First Look into the Mind of the Giraffe

By Posted on 5 min read 853 views

A baby giraffe was born the other day at the Toronto Zoo! I’m so excited. Her name is Baby Long Legs. Take at look at her here.

Welcome to the world, Baby Long Legs!

I’ve been meaning to talk about a really cool research study that was done with giraffes so now is the perfect time, to celebrate Baby Long Legs!

We know quite a bit about giraffe biology, their behaviour, and their interactions with their surroundings, but as far as I know, nothing is known about their cognition: what goes on inside their head. Until now!

A group of scientists from Spain and Germany noticed that like chimpanzees, giraffes live in fission-fusion societies and eat quite a variety of plants. A fission-fusion society is where animals come together into groups, but over time separate, perhaps come back together, or form different groups. For example, a large group of animals may form smaller groups while they are eating or sleeping throughout the day.

Chimpanzees are well-known for being quite intelligent. (I’ll have to write a blog or two about them some time. They are amazing.) So if giraffes are similar to chimpanzees in certain ways, could they be intelligent too? The scientists decided to design some experiments to find out if they could get a glimpse into giraffe cognition.

Where to start? Well, one of the most basic things we can do is realize that the world is made up of objects that are separate from our own bodies, and that these objects exist in time and space. Taking this a bit further, we can also realize that objects continue to exist even if we can no longer see them. Scientists call this object permanence. Object permanence develops gradually in humans when we are babies, but it also occurs in other primates and birds such as corvids and parrots. Are giraffes capable of object permanence?

One way object permanence is tested is by showing the animal an object that it really likes (such as a piece of food), then hiding it under one of several identical opaque containers, and allowing the animal to choose which container the food or object is hiding under. If the animal picks the correct container on its first choice, it has passed the test of object permanence.

This is what the scientists did with three giraffes from the Barcelona Zoo and three giraffes from the Leipzig Zoo. They separated each giraffe inside their indoor enclosures. An experimenter approached each giraffe with two containers. The giraffe watched as the experimenter placed a piece of apple or carrot (depending on what that particular giraffe liked best) in one of the containers. The experimenter then closed both containers and presented the containers to the giraffe to make a choice. If the giraffe chose the container that held the apple or carrot, this was evidence of object permanence.

An experimenter showing the contents of the container to a giraffe before closing the lids and allowing the giraffe to make a choice. One of the containers holds apples or carrots. Source: Journal of Comparative Psychology.
A giraffe choosing one of the containers. Look at that beautiful tongue! Source: Journal of Comparative Psychology.

So, how did the giraffes do? They overwhelmingly chose the container with the food! They showed evidence of object permanence.

(I should note a couple of things before moving on. It is important that the giraffes did not choose the correct container simply because they could smell the food inside. The experimenters did a test where they hid the food in one of the containers and the giraffes didn’t see which container the food was placed in–they were just presented with two closed containers. In this case, the giraffes chose the container with the food only half the time, which is what we would expect if they were just choosing containers randomly. This means the giraffes could not choose the correct container based on smell. The other important point is that whether they mean to or not, the experimenter could give subtle cues to the giraffe about which container to choose. To prevent this, the experimenter closed their eyes when they presented the giraffes with the containers. The experimenter could tell which container the giraffe chose because they could feel the giraffe bunt it with its nose or touch it with its tongue (see photo above).)

But the scientists did not stop there. Next they gave the giraffes a memory test. After closing the lids of the containers, the experimenter waited 30 seconds, 60 seconds, and then 120 seconds, before allowing the giraffe to make a choice. (In the experiment described above, the delay between closing the lids and allowing the giraffes to choose was only 2 seconds.) In this case, giraffes still correctly chose the container with the food after a 30 second delay, again showing object permanence. But for the 60 second and 120 second delays, they chose the correct container only half the time. This suggests that maybe giraffes have limits to their memory or attention.

For their last experiment–and this is really cool–the scientists wanted to see if giraffes could choose the container with the food based on sound cues. The experimenter turned their back on the giraffes while putting the food in one of the containers, so the giraffe couldn’t see which container held the food. With both containers closed, the experimenter turned around to face the giraffe and shook the container that held the food, which made a loud rattling sound. The giraffes chose the container with the food!

Then, instead of shaking the full container, the experimenter shook the empty container. In this case, the giraffe would have to figure out that the container that was shaken did not contain anything, so they could have to choose the other container, which contained the food. Unfortunately, the giraffes had a hard time with this situation and did not choose the correct container very often. As the scientists point out, the giraffes might not have been using sound cues at all but instead chose the container that was shaken. This would result in the correct choice when the full container was shaken, but not when the empty container was shaken.

A clever thing the scientists did was keep track of the giraffe’s body position throughout the testing. After seeing which container was full, did the giraffes simply turn their body towards the full container as a trick to remember which container to choose? Turns out sometimes the giraffes did this, but they did not use this tactic consistently. The most successful giraffe, Ashanti, never seemed to use her body position at all. Whether or not giraffes adjusted their body position to ensure they chose the correct container, I think the results of these experiments show that giraffes are quite clever! And also, given that giraffes were successful participants in these experiments, this paves the way for more discoveries to be made about giraffe cognition.

Which makes me marvel at what must be going on in Baby Long Legs’s mind as she explores this big new world around her. Welcome, Baby Long Legs!

Baby Long Legs and her mom. Source: blogTO.

Reference

Caicoya, Á. L., Ensenyat, C., Amici, F., & Colell, M. (2019). Object permanence in Giraffa camelopardalis: First steps in giraffes’ physical cognition. Journal of Comparative Psychology, 133(2), 207-214. http://dx.doi.org/10.1037/com0000142

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Animals

“Murder Hornets”

By Posted on 5 min read 526 views

Lately there has been a lot of alarmist news reports about “murder hornets.” I thought I’d weigh in.

“Murder hornets” is the name given to the Asian giant hornet, Vespa mandarinia. Interestingly, there is no English common name for Vespa mandarinia. “Murder hornet” was coined by the media. In Japanese, this hornet is referred to as “great sparrow bee.” (Much nicer name than “murder hornet,” eh?) In Chinese, it is called “tiger head bee.” (But note: hornets are NOT bees! Check out the differences between bees and hornets here.)

The Asian giant hornet is one of the largest wasps in the world: queens can be 2 inches long with a wingspan of 3 inches. Workers are a bit smaller at 1.5 inches long. As their name implies, these wasps are found in Asia, specifically in parts of Japan, China, India, and Sri Lanka. But they have hit the news because they were recently found in British Columbia, Canada, and Washington state.

Close up of an Asian giant hornet. Photo source: National Geographic.
Asian giant hornets attacking a honeybee hive. Photo source: Scientific American.

Why are they called “murder hornets?” Asian giant hornets need to feed protein to the baby hornets in their nest so they can grow into adults. Where do they get the protein? From the bodies of other insects, particularly honeybees. Once an Asian giant hornet finds a honeybee hive, she’ll start chopping the heads off the honeybees using her huge mandibles (mouthparts). The hornet is after the honeybee’s thorax, which is the middle part of the body which is rich in protein because it contains all the honeybee’s flight muscles. The hornet turns the thorax into a “meatball” and carries it back to her nest.

When an Asian giant hornet finds a honeybee hive, she will wipe her rear end against the hive, leaving a pheromone, or chemical signal, which will alert her sister hornets to join in on the massacre. If enough sisters join in, they can slaughter the honeybee colony. A group of 20-30 Asian giant hornets can kill 5,000 to 25,000 honeybees in a few hours. (There are about 100 worker hornets and one queen hornet in an Asian giant hornet nest.) Once the hornets have slaughtered the honeybees, they will pilfer all of the larvae (baby honeybees) and bring them back to their nest to feed their own babies, since larvae are also high in protein.

However, the poor honeybees are not defenceless. Japanese honeybees (Apis cerana japonica) have lived with the Asian giant hornet for a long time and has a pretty cool strategy for fending off these murderers. Japanese honeybees can smell the pheromone that an Asian giant hornet leaves on their hive, and they start assembling the troops. They will gather in the hundreds, and when the hornet is entering the hive they will completely surround her, forming a “bee ball.” About 500 honeybees form a tight ball around the hornet, and they buzz their wing muscles to raise their body temperature so much that they cook the hornet to death! Scientists found that the temperature of a bee ball can rise to 47 degrees Celsius, which is lethal to the hornet but not to the bees. The hornet also suffocates with all of the carbon dioxide produced by the honeybees.

Left: A “bee ball” of about 400 honeybees surrounding an Asian giant hornet. Right: A dead Asian giant hornet and a few honeybees after their victory. Photo source: Nature journal.

Of course, if too many Asian giant hornets descend upon the honeybee hive at once, the honeybees can’t make enough bee balls to fend off the hornets, and they lose the battle.

So, why is the media freaking out about “murder hornets?”

Murder hornets will kill all the honeybees!

Yes, honeybees in North America would be in trouble if attacked by Asian giant hornets. Honeybees in North America are a different species from the ones in Japan who have developed the bee ball strategy. Here, our honeybees are Apis mellifera, the European honeybee, and they have not had to deal with Asian giant hornets. So, they don’t know the strategy of forming a ball to cook and suffocate the intruder to death. Our honeybees would be slaughtered by Asian giant hornets. BUT…there has been only a handful of sightings of Asian giant hornets in British Columbia and Washington. That’s it. Authorities are taking measures to get rid of the hornets if they are seen.

Murder hornets are dangerous to humans! They sting! They can kill us!

Yes, like all other hornets, Asian giant hornets can sting. And because they are so big, their sting can really pack a punch. There are reports that they can sting through the protective suits that beekeepers wear. BUT…like bees and other hornets, they will only sting if threatened (for example, if you swat at them), and if they feel that their nest is threatened. There is also a statistic floating around that “murder hornets” kill about 50 people a year. BUT…this includes all of Asia where the hornet is found, which is a huge swath of land. AND…to put things in perspective, an average of 62 Americans are killed each year by bees and wasps, due to allergic reactions (not all people are allergic to stings).

Murder wasps will multiply and take over the world!

Relax. As mentioned, they have only been found in a few places in British Columbia and Washington. If any good can come from the viral spread of the sensationalist news stories, it’s that people will be more aware and can help spot these hornets if they do start to multiply.

How did “murder hornets” end up in North America, anyway? We’re not sure. Some experts suspect that they hitchhiked on cargo that was shipped from Asia. Interestingly, that’s how some bumble bee species were thought to become established in some parts of the world!

References

Ono, M., Igarashi, T., Ohno, E. & Sasaki, M. (1995). Unusual thermal defence by a honeybee against mass attack by hornets. Nature, 377, 334-336.

Skvarla, M. J. (2020, May 6). Asian giant hornets. PennState Extension. Retrieved May 8, 2020 from https://extension.psu.edu/asian-giant-hornets

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Animals

Sharks and Music

By Posted on 5 min read 468 views

Animals that live under water can use sound to find prey, escape from predators, and find their way around. For example, a fish in distress who is thrashing around can alert a bigger fish that a tasty morsel is nearby.

Sharks are one type of fish that can rely on sound to catch their next meal. As far as we know, sharks don’t make any sounds themselves (unlike, for example, dolphins, who communicate using clicks and squeaks and other sounds. Which is incredibly cool. I’ll have to blog about dolphins some time). Sharks do have an inner ear, though, and tests have shown that they can detect certain frequencies.

A couple of scientists in Australia decided to see whether sharks can learn where to get food based on music cues. Scientists have studied the behaviour of sharks for a long time, often using things that the sharks can see, rather than hear. These two Australian scientists realized that we don’t know much about how flexible sharks can be in terms of learning things about sound cues. So, they designed an experiment with Port Jackson sharks–a species of shark that we know relatively little about when it comes to cognition, or mental processes.

Some info about the sharks: Port Jackson sharks (we’ll call them PJs for short) live along the coast of Australia. Here is a map with orange dots showing where these sharks have been sighted:

Source: The Australian Museum.

PJs are benthic sharks, which means they hang out around the ocean floor. They eat sea urchins, molluscs, crustaceans, and fishes. As you can see from the photo below, PJs don’t have the big, ferocious-looking teeth that sharks are usually known for. But their bite can still pack a punch!

Source: iNaturalist.

On the smaller side of sharks, male PJs generally grow to only 75 cm in length, and females grow 80-95 cm. (75 cm is roughly the length of a grown man’s arm.) PJs are pretty harmless to humans, as you can see from this short, up-close video that a scuba diver took of several PJs:

Source: The Australian Museum.

So, back to the music experiment. The scientists used eight young PJs (four male, four female) that had been raised at the Sydney Institute of Marine Science (SIMS) from wild-caught eggs. (Click here to learn more about SIMS.) The sharks lived in huge seawater tanks and once the scientists’ experiment was finished, all of the sharks were released into the wild where their eggs had been found.

The scientists put a special arena into a tank of seawater:

A diagram of the arena the scientists used in their music experiment. Source: Animal Cognition journal.

Only one shark was ever in the arena at a time, and they gave the PJs lots of opportunities to swim around the arena to get used to it. The scientists actually gave each of the eight PJs a “boldness score”: They placed the shark in the start box with the sliding door closed, and when they opened the door to give the shark access to the rest of the arena, they timed how long it took for the shark to come out and explore. It turns out the male PJs were more shy than the female PJs: they took longer to come out of the start box.

So, where does the music come in? As you can see in the diagram above, there was a speaker at the opposite end of the arena. The scientists played a 20-second clip of a jazz song after the shark was let out of the start box. (They were careful to select a clip that had sound frequencies that were within the sharks’ hearing range.) For half of the sharks, if they swam to the far right-hand corner of the tank when they heard the music, then they got a prize: a tasty piece of squid (the sharks’ favourite food!). For the other four sharks, if they swam to the far left-hand corner of the tank when they heard the music, they got some squid. So, the sharks had to learn that the music was a cue to swim to a specific corner of the arena.

(Click here to listen to the jazz music that the sharks heard.)

As a test, the scientists played the music a few times and did not give the sharks any squid, to see if the sharks would swim to the correct corner. Five of the eight sharks passed the test: they learned to swim to a specific corner of the tank when they heard the jazz music.

Next, the scientists added classical music to the mix. Again, they chose a 20-second clip that had sound frequencies that the sharks would be able to hear. This time, if the PJs heard the jazz music they were to swim to the same corner as before to get some tasty squid. However, if the heard the classical music, they had to swim to the opposite corner to get squid. In other words, the type of music that was played to the sharks told them which corner to swim toward.

(Click here to listen to the classical music that the sharks heard.)

Interestingly, the sharks did not do well at this task. They kept swimming to the far right corner of the tank, regardless of which music was played. Even the five sharks who, in the previous task, learned to swim to the left when jazz music was played, swam to the right. In other words, the five sharks who were successful before did worse in this task. Why did all the sharks favour the right side of the tank so much? We’re not sure.

So there was no evidence that the PJs were able to tell the two types of music apart. Or, if they could tell them apart, their behaviour certainly didn’t show it. And remember how the scientists scored the “boldness” of each shark at the beginning of the experiment? Well, it turns out “boldness” did not have an effect on the sharks’ learning ability (or lack thereof).

It is possible that the five PJs who originally swam to the correct corner of the tank learned the simple rule of “swim to the right (or left) corner of the tank,” and basically ignored the jazz music. They figured out how to get a squid meal using the simplest way possible. They didn’t need any music. Pretty bright if you ask me.

To learn more about PJs, click here to check out the Australian Museum.

Reference

Vila Pouca, C., & Brown, C. (2018). Food approach conditioning and discrimination learning using sound cues in benthic sharks. Animal Cognition, 21, 481-492. https://doi.org/10.1007/s10071-018-1183-1

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Animals

Penguin Personalities

By Posted on 5 min read 2661 views

April 25th is World Penguin Day! To honour these delightful birds from the southern hemisphere, I thought I’d tell you about a really neat study on penguin personalities.

If you’ve ever had the opportunity to watch penguins on video, at a zoo, or in the wild (lucky you!), they are quite the charismatic little creatures. Even their waddles seem full of personality. To see a bit of their behaviour, here is a short, cool video of African penguins at the San Diego Zoo:

So, what exactly is personality? Scientists who study animals think of personality as differences in behaviour between individuals, and these behaviours tend to remain steady no matter what setting the individual is in. So, an animal that has a friendly personality tends to be friendly regardless of whether they are with others who are familiar or unfamiliar to them, and no matter what the circumstances are.

Scientists are interested in animal personality because what they learn can help us give captive animals, such as those in zoos, the best lives possible. For instance, if some animals are seen to be curious, zookeepers can provide them with new objects on a regular basis so that they have things to check out and play with. If some animals are seen to be shy, their zoo enclosures could be built so that they include some spaces where the animals can hide and be alone.

At the Edinburgh Zoo in Scotland, there is an exhibit with 129 penguins. It is one of the largest outdoor penguin exhibits in Europe, with a huge freshwater pool, and it includes three different species of penguins that all live together: northern rockhopper penguins, gentoo penguins, and king penguins. A group of scientists thought it would be interesting to see if the three species of penguins have different personalities. They randomly chose 43 penguins: 21 northern rockhoppers, 14 gentoos, and 9 king penguins.

Northern rockhopper penguins. Photo courtesy of Encyclopedia Britannica.
Gentoo penguin. Photo courtesy of Encyclopedia Britannica.
King penguins. Photo courtesy of the Australian Government.

To measure personality, the scientists came up with a list of 31 different traits. Each trait was rated on a scale from 1 (the trait was never seen) to 12 (the trait was always seen). Who rated each of the 43 penguins on all 31 traits? Why, the two zookeepers, of course! They knew the penguins the best. But importantly, the two zookeepers did their ratings separately and did not talk about their ratings, so that they would not influence each other.

Here is the list of 31 personality traits for the penguins. Some of them are pretty interesting.

  • Active
  • Aggressive to other penguins
  • Aggressive to familiar people
  • Aggressive to Keepers
  • Aggressive to unfamiliar people
  • Aggressive to observer
  • Calm
  • Cooperative
  • Curious
  • Dominant
  • Eccentric
  • Excitable
  • Friendly to other penguins
  • Friendly to keepers
  • Friendly to familiar people
  • Friendly to unfamiliar people
  • Friendly to observer
  • Fearful of other penguins
  • Fearful of familiar people
  • Fearful of unfamiliar people
  • Fearful of keepers
  • Fearful of you
  • Insecure
  • Playful
  • Self-assured
  • Smart
  • Solitary
  • Tense
  • Timid/shy
  • Vocal: aggressive
  • Vocal: non aggressive

How did the zookeepers tell the penguins apart? Each penguin has a coloured band on its wing, and depending on which side the band is on and what colour(s) the band is, the zookeepers could tell which penguin was which. Below is a list of the 43 penguins that were included in the study. Some of the names are hilarious!

(R = band on right side; L = band on left side; K = King penguin; NR = Northern rockhopper penguin; G = Gentoo penguin)

  • Blue (Blue, K)
  • Nils (Purple, R, K)
  • Fingal (White, R, K)
  • Maclean (Red/Yellow, R, K)
  • Bow (Red/Green, R)
  • Yoepie (Gold, R, K)
  • Alfie (Lt Blue/Green, R, K)
  • Kongo (Orange, R, K)
  • Dennis (Black/Red, R, K)
  • Mrs. Wolowitz (Orange/White, L, NR)
  • Mrs. White (White, L, NR)
  • Helena (Dk Blue/White, L., NR)
  • Millie (Gold/Yellow, L, NR)
  • Al (Gold/Orange, R, NR)
  • Balboa (Gold/Pink, R, NR)
  • Dwaine (Pink/Green, R, NR)
  • Nestor (Dk Blue/Pink, R, NR)
  • Tristan (Lt Blue/Yellow, R, NR)
  • Eddie (Black/Green, R, NR)
  • Issy (Lt Blue, Yellow, L, NR)
  • Gordon (Brown/Gold, R, NR)
  • Isla (Lt Blue/Yellow, L, NR)
  • Jura (Gold/Yellow, R, NR)
  • Wesley (Gold/White, R, NR)
  • Bruce (Dk Blue/Gold, R, NR)
  • Penny (Brown/Gold, L, NR)
  • Pinhead (Gold/Orange, L., NR
  • Amy (Gold/White, L, NR)
  • Brucetta (Dk Blue/Gold, L, NR)
  • Batman (Gold, R, NR)
  • Boy (Blue/Orange/Yellow, R, G)
  • Mrs. Spain (Orange/White, L, G)
  • BB (Dk Blue/Lt Blue, L, G)
  • Snowflake (Unbanded, G)
  • Mary (Dk Blue/Red, L, G)
  • Mrs. Colin (Lt Blue/Yellow, R, G)
  • Boo (Lt Blue/White, L, G)
  • Poppet (Dk Blue/White, L, G)
  • Dolores (Grey/White, L, G)
  • Buzz (Lt Blue/Grey, R, G)
  • Mr. Spain (Red/Yellow, R, G)
  • Chip (Orange/Yellow, R, G)
  • Kevin (Gold, R, G)
A penguin with a band on its wing. Who do you think this is? Photo courtesy of the Edinburgh Zoo.

After the two zookeepers finished rating all 43 penguins on all of the 31 personality traits, the scientists gathered all of the ratings and figured out how similar or different the ratings were. They discovered that, for the most part, the zookeepers had similar ratings for the penguins for traits such as aggressive to other penguins, aggressive to the keepers, calm, curious, friendly to keepers, playful, and vocal-aggressive. On the other hand, the zookeepers had less agreement for traits like eccentric, excitable, insecure, smart, and timid/shy. These traits were probably trickier for the zookeepers to determine from the penguins’ behaviour.

So, were there differences in personalities between the three species of penguins? Yes! The scientists discovered that gentoo penguins were more active than the northern rockhopper penguins. The northern rockhopper penguins were much calmer. Compared to the northern rockhopper penguins, gentoo penguins were more curious and less friendly with other penguins. Gentoo penguins were also more playful, and were much more vocal than the other two species of penguins.

Overall, the scientists found that the three species of penguins at the zoo had distinctive personality traits. Which is really cool, considering that the three species all live together in the same enclosure, have close contact, and experience the same routines each day (like feeding time). Despite this, each species has their own individuality.

Click here to watch a live webcam of the penguins at the Edinburgh Zoo!

Check out this video of penguins who had been set loose inside Chicago’s Shedd Aquarium:

Reference

Pastorino, G. Q., Preziosi, R., Faustini, M., Curone, G., Albertini, M., Nicoll, D., Moffat, L., Pizzi, R., & Mazzola, S. (2019). Comparative personality traits assessment of three species of communally housed captive penguins. Animals, 9, 376. https://www.mdpi.com/2076-2615/9/6/376

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