Dear Shark Man, are the relative sizes of sharks in the “baby shark” dance scientifically accurate?

Welcome to  Dear Shark Man, an advice column inspired by a ridiculous e-mail I received. You can send your questions to me via twitter (@WhySharksMatter) or e-mail (WhySharksMatter at gmail).

Dear Shark Man,
Are Daddy and Grandpa sharks really morphologically bigger than Mommy and Grandma sharks?
Sincerely,
Addicted to “Baby Shark” in Arizona


Dear Addicted,

Thank you for a great question, which allows me to continue teaching science from things that go viral on the internet. First, let’s make sure that everyone’s on the same page about what precisely you are inquiring about.

You’re referencing the viral song “Baby Shark,” which has been made popular recently by the online educational company Pinkfong. (Though, let’s be clear here, the song is much older, I remember singing it at summer camp 25 years ago). The Pinkfong version of the song is an undeniable hit, inspiring remixes, educational parodies, clothing, food,  and even the baby shark challenge.

In case you haven’t seen it yet, you’re welcome:

Anyway, in the song and associated dance, a series of shark age classes are named, and the dancer moves their hands and arms progressively larger to signify an increased gape size (size of open mouth) associated with changes in shark life history. Baby shark is the smallest, mommy and grandma shark are the next largest, and daddy and grandpa shark are the largest. Additionally, both grandma and grandpa shark are shown to have no teeth.

So let’s get back to your question, Addicted. How accurate is the dance associated with “Baby Shark” in terms of portraying the relative dimensions of gape sizes associated with different life history stages of sharks?

Is the gape size of a reproductively mature shark (male or female) larger than that of it’s newborn offspring, which are called either “pups” or “young of year ” or “neonates”? Yes, because the whole shark would be larger. This makes intuitive sense, I hope! Indeed, a mommy or daddy shark would have a dramatically bigger mouth than a baby shark. The size disparity becomes a little blurrier when you’re talking about not-quite-reproductively-mature juveniles and have-just-become-reproductively-mature young adults, but the difference between baby and mommy or daddy sharks is noticeable.

Are reproductively mature adults old enough to have reproductively mature offspring going to be approximately the same size as their reproductively mature offspring? In other words, are grandma sharks the same size as mommy sharks, and are grandpa sharks the same size as daddy sharks? No. Sharks have what’s called “indeterminate growth,” which means that they continue growing throughout their lives. Therefore, grandma sharks would be larger than mommy sharks, and grandpa sharks would be larger than daddy sharks. This difference in size (and associated gape size) would not be as drastic as the difference in size between that of mommy/daddy sharks vs. baby sharks, however, because growth rate slows down as sharks age.

Next, are reproductively mature adult male sharks larger than reproductively mature adult female sharks? In other words, are daddy sharks bigger than mommy sharks, and are grandpa sharks bigger than grandma sharks? Typically not! In many (I’m always hesitant to say “all” because sharks are weird, but I don’t know of a counterexample) species of sharks, the females are larger than the males. The reasons for this are complex, but if you think of it in terms of how much energy and effort and space it takes to make sperm vs. eggs (or how much energy and effort and space it takes to have pups grow inside you), it makes some intuitive sense. In some other fish species, the smaller younger individuals are all males, and they *turn into* females when they age and grow, a phenomenon known as protandrous sequential hermaphroditism. (This happens with clownfish, which would have made Finding Nemo a very different movie if they paid a little more attention to scientific accuracy).

Finally, would older grandma and grandpa sharks have lost all their teeth as they aged? In reality, many shark species can continually regrow new teeth throughout their lifetime (sometimes going through thousands of teeth per individual shark). This is good, because when you’re a wild predator and you don’t have any teeth, you can’t eat and you, um, die.

So in summary, Addicted, “Baby Shark” is catchy as hell, but is not a new song, and the associated dance is not scientifically accurate. Put another way, the song is not quite right, doo doo doo doo doo, not quite right, doo doo doo doo doo, not quite right doo doo doo doo doo, not quite right.


If you appreciate my shark research and conservation outreach, please consider supporting me on Patreon! Any amount is appreciated, and supporters get exclusive rewards!

Dear Shark Man, what’s the deal with those notches on shark tails?

Welcome to  Dear Shark Man, an advice column inspired by a ridiculous e-mail I received. You can send your questions to me via twitter (@WhySharksMatter) or e-mail (WhySharksMatter at gmail).


Dear Shark Man,

Why do sharks tend to have those little notches in their tail fin? Is it like an aerodynamic thing? If you were to fill it with more shark does something magic happen?
Sincerely,

Grateful in Georgia

Dear Grateful,

That’s a great question, and I didn’t know the answer! I reached out to an expert in the structure and function of shark fins, Dr. Brooke Flammang of the New Jersey Institute of Technology, to ask. Here’s what she told me.

“Sadly, there has not (yet) been a study focused on the fluid dynamics of the subterminal lobe (the flappy bit of tissue at the end of the tail, which moves freely because of the notch) of the shark tail. However, we can come up with a really good hypothesis about how it works!

Sharks that have the notch and the subterminal lobe are mostly in the order Carcharhiniformes (and also Squalus, which is the odd duck for everything). In Carcharhiniforms, as compared to, for example, Lamnids, the angle between the dorsal and ventral lobes is small, they have a low aspect ratio, and tails are more flexible. This suggests that Carchariniforms do not generate as much power with every tailbeat as Lamnids do.

Sharks with subterminal lobes tend to be slow-swimming, epibenthic/benthic/demersal dwellers. If you are swimming slowly in an undulatory fashion, you need to generate a considerable amount of force to maintain forward propulsion because you have less inertial benefit than when you are swimming quickly with a stiffer, more streamlined body. One way to increase force generation is to increase the momentum being added to the surrounding fluid – which is to say, you need to move more water away to push yourself forward.

The subterminal lobe adds surface area but is not stiff, lacking muscular control, and trails slightly behind the rest of the dorsal lobe during a fin beat. Because it trails behind, it extends the duration of time that fluid builds momentum before being shed from the tail (and thus generating thrust). Such passive thrust enhancement would likely only be effective at slow swimming speeds with more flexible tails, such as we see within the Carchariniformes. If you fill in the notch (and lose the flappiness of the subterminal lobe) you would decrease the efficacy of this enlarged area of flexible tissue in the tail considerably.”

Congratulations, Grateful, you’ve found a question that no one has explicitly studied, and given an expert an idea for a future project! We can only guess what would happen to  shark’s swimming behavior if this notch were filled in, and Dr. Flammang’s guess is as good as anyone’s!


If you appreciate my shark research and conservation outreach, please consider supporting me on Patreon! Any amount is appreciated, and supporters get exclusive rewards!

Dear Shark Man, do open ocean sharks use nursery areas?

Welcome to  Dear Shark Man, an advice column inspired by a ridiculous e-mail I received. You can send your questions to me via twitter (@WhySharksMatter) or e-mail (WhySharksMatter at gmail).


Dear Shark Man,

I know that sharks that live close to the coast sometimes use “nursery areas” when they are young. Do open ocean sharks also use nursery areas?
Sincerely,
Nosey in North Carolina 

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Dear Shark Man, can rubbing a shark’s snout cause blindness?

Welcome to  Dear Shark Man, an advice column inspired by a ridiculous e-mail I received. You can send your questions to me via twitter (@WhySharksMatter) or e-mail (WhySharksMatter at gmail).


Dear Shark Man,

Someone I follow on Instagram posted this earlier this week. In this post, she claims that a shark became blind in one eye because SCUBA divers were regularly rubbing it’s snout. Is that a thing? It doesn’t seem like a thing.

Sincerely,
Frustrated in Fort Lauderdale 

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Galeophobia, Shark Teeth, and Non-Expert Awareness Campaigns: Dear Shark Man, Volume 5

Welcome to Volume #5 of Dear Shark Man, an advice column inspired by a ridiculous e-mail I received. You can send your questions to me via twitter (@WhySharksMatter) or e-mail (WhySharksMatter at gmail).


Dear Shark Man,

What’s the history of the shark’s cultural image as a sneaky aggressive predator? Do other cultures see it differently?

Sincerely,
Imaginative in Irvine

Dear imaginative,

Much of the large-scale public fear of sharks we see today can be traced to the movie “Jaws” (read my Gizmodo article about this here). Shark conservation biologists actually use the term “the Jaws effect” in peer reviewed scientific literature. Terror of sharks resulting from that movie is fairly common even among people you wouldn’t expect; for example, both of my parents are outdoorsy and have post-graduate degrees, and yet both reported being afraid to go swimming in pools or lakes the summer after Jaws came out. Personally, I don’t think that modern shark b-movies like “SharkNado” or “Two-Headed Shark Attack” inspire the same level of public misunderstanding because they’re obviously silly, but others disagree.

Media coverage of shark bites also plays a major role. If someone gets bitten by a shark anywhere in the world, it’s headline news everywhere even if the bite isn’t severe enough to require more than a band-aid. In Australia, 38% of reported “shark attacks” didn’t even involve any injury at all. This is part of why I, along with many other shark scientists, have called on the popular press to avoid the inflammatory and inaccurate term “shark attack” in favor of a typology of other terms (shark sighting, shark encounter, shark bite, fatal shark bite).

Other cultures absolutely see sharks differently. Where I now live in western Canada, coastal First Nations have stories about a supernatural being called the Dogfish Woman. In some South Pacific cultures, sharks are seen as spirits of ancestors called aumakua (briefly referenced in Moana, see below), and there are even shark gods like Dakuwaqa.

Maui in the form of a shark, from Moana. You’re welcome.

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Vegetarian sharks, non-lethal research, and friggin’ laser beams: Dear Shark Man, Volume 4

Welcome to Volume #4 of Dear Shark Man, an advice column inspired by a ridiculous e-mail I received. You can send your questions to me via twitter (@WhySharksMatter) or e-mail (WhySharksMatter at gmail).


Dear Shark Man,

I feel more and more guilty about my own meat consumption. I wonder, are there any vegan sharks?

Sincerely,
Eager in England

Dear Eager,

There are more than 500 species of sharks, and they range widely in shape, size, habitat, and behavior. However, every single species eats animals. Many eat fish, some eat invertebrates, and few eat mammals and birds, but they all eat animals. Even the filter-feeders like whale sharks are eating zooplankton, which are (tiny) animals.

Bonnethead sharks have been documented with seagrass in their stomachs, which is likely the result of accidentally ingesting seagrass while eating crabs that live among the grass. (Sometimes I fail to pick all the lettuce off of my turkey sandwich and eat it accidentally, that doesn’t mean I’m seeking out lettuce or that lettuce is a major component of my diet). Recent work by Samantha Leigh has shown that bonnetheads may be able to partially digest this seagrass, which is pretty neat. However, that does not make them vegans, or even vegetarians.

Incidentally, a member of an influential marine conservation family whose name rhymes with Mousteau once claimed that there are more than 1,000 species of sharks and most of them are vegetarian, which is…extremely not correct.

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Shark species names and hurricane sharks: Dear Shark Man, Volume 2

Welcome to volume #2 of Dear Shark Man, an advice column inspired by a ridiculous e-mail I received. You can send your questions to me via twitter (@WhySharksMatter) or e-mail (WhySharksMatter at gmail).


Dear Shark Man,

I know how you feel about sandbar sharks (even though I’m still #teamgoblinshark), but can we agree that Ninja Lanternshark is the best common name for a shark? Also, if you had an opportunity to name a shark, what would you name it? I’d name mine Storm Shark, not because of the meteorological event, but because Storm is Aquaman’s mighty seahorse steed.

Sincerely,
La Requin in Lake Buena Vista

Dear La Requin,

Ninja Lanternshark is a pretty sweet common name. My friend Vicky Vasquez was involved in the discovery and description of that species, which also has a cool scientific name (benchleyi, named after Jaws author and eventual shark conservationist Peter Benchley). If you haven’t read the great Hakai magazine story about this species, you should.

As an ecologist and conservation biologist, I am unlikely to get the opportunity to name a shark, but that doesn’t mean I haven’t thought about this. I’d love to see shark species named after influential shark conservation advocates, particularly those who engage in science-based conservation advocacy. If a new species of cownose ray is discovered, I hope that folks will consider naming it after Shark Advocates International President and frequent Southern Fried Science guest blogger Sonja Fordham, for example. And I certainly wouldn’t turn down a species named after me, if any taxonomists are reading this, though there are certainly plenty of more deserving people.

Incidentally, I have a colleague who studies marine mammal parasites. I’ve told her that I will donate to a conservation charity or her choice if a parasite that significantly annoys (but does not kill) dolphins is named after Southern Fried Science.

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