Do Kangaroos Eat Meat?

I don’t remember the exact circumstances that brought this one up, but out of the blue my son asked the following question: “Do kangaroos eat meat?”

“Uhm…” I temporized, racking my brains. I know a few odd facts about kangaroos – for example, their legs have evolved so that once they start hopping they barely have to use any energy to continue hopping in a straight line at a steady pace, and females have two uteruses – but I suddenly realized that I have [i]no idea[/i] what they eat. “I don’t know,” I admit. “I think they’re herbivores, though.”

“No, they don’t eat meat,” my wife adds. “They do eat bugs, though.”

“Bugs are meat!” my son retorts.

Well played, son. Well played.

What do kangaroos eat?

This looks pretty straight forward. Kangaroos are herbivores. Most of them are “grazing herbivores”, meaning that they eat kind of like cattle – grass, leaves from shrubs and low-hanging trees, fungus if they find it, that sort of thing. They crop the plant matter with their sharp front teeth and grind it with their molars before swallowing. As the molars wear down, new molars grow at the back of the mouth and push forward, shoving out the worn front molars.

Also like cattle, kangaroos have two stomach chambers and chew their cud. The plant matter they swallow is held in the front chamber, where it is fermented by bacteria and fungi until it is regurgitated and chewed and swallowed again. Unlike cattle, though, they don’t fart. Cows fart because their stomach bacteria produces methane as they ferment their cud. Kangaroo stomach bacteria, however, produce hydrogen that is changed into acetate which is used for additional energy.

That seems pretty straight forward

It did, didn’t it? But then I saw this:

Wait. What the heck was that?

That was a kangaroo eating a bird on a beach.

But… but… wait! You said they were herbivores!

Yeah, that’s what I said. And it makes sense to say that, because they’re adapted to a plant-eating diet. And we all learn from an early age that animals fit neatly into one of three categories: herbivores (who eat plants), carnivores (who eat meat), and omnivores (who eat meat and plants). But it turns out that nature is messy and doesn’t really care at all about the neat little categories human beings come up with to explain things.

The animals we call “herbivores” are best thought of as “animals that are adapted for, and primarily consume, a plant-based diet”. Let’s start with the easy proof of that: do you really think that a cow would spit out a worm or a mouse if it picked it up while tucking in to a bale of hay? The answer is, it might. Or it might keep chewing. Cows have to eat a lot, after all.

But it goes beyond simple things like “oops, I ate a mouse”. Deer will actively prey on bird nests, consuming the eggs and even the hatchlings within. They’ll also rummage through animal remains, both to eat partially digested foods in the remains and to eat the meat left behind – going as far as eating human remains.  Deer aren’t the only predatory “herbivores”, either. Cows have been observed eating chickens and giraffes have been observed eating animal bones. Hippos have been observed hunting, killing, and eating other animals.

In a less bloody example of “eating outside your assigned category”, alligators and crocodiles will eat fruit and vegetables.  And anyone who’s been around cats or dogs has seen them eat grass and houseplants.

So, uhm, why?

Sadly, I couldn’t find any specific explanation for this behavior. I assume that it happens for the same reason any animal eats anything at all: either it tastes good, or there’s something in the meat the animal needs, or both. Some nutrients may just be easier to get from animals – calcium, for instance, is easier to obtain in large quantities if you eat a bone. And a chicken has a lot more protein than the same weight of grass.

So, yes. Kangaroos do eat meat. So do a lot of other animals you wouldn’t expect to be eating meat. But they’re not predators, not really. Primarily herbivorous animals just aren’t adapted for a meat-heavy diet, or to hunt down and kill other animals.

Except for hippos.  They’ll probably just kill you for fun.

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Who Is Your Favorite President Riding A Dinosaur?

“Dad?” my son asks, looking at me from the other end of the couch, “who’s your favorite president?”

I look up from my book. It’s out of nowhere, and pretty obviously a “dad, pay attention to me” kind of question, and it’s hit me out of left field. “Well, I don’t…” I start to say.

“Only he has to be riding a dinosaur!” my son adds. “And it can be any dinosaur you want, as long as it’s real!”

How on earth do you answer that?

We’re dying to find that out, really.

All right. So, clearly this is a two-part question. “Who is my favorite president?”, and then “what is my favorite dinosaur that someone could read?” How hard could this be?

The internet never fails to deliver

Who is your favorite president?

That… is a really good question. I could easily list my top two or three least favorite presidents, but I’ve never really thought about which one of them is my favorite. I will say I’ve got an unreasonable soft spot in my heart for Ronald Reagan, mostly because the 1978 Carter vs. Reagan election is the first one I really paid any attention to, and I was seven years old (the same age as my son), and my mom was a Reagan Republican and my dad was a Reagan Democrat. So, yeah. There was an influence there, because when you’re seven years old your parents are the smartest and best people in the whole planet.

My political views have shifted since I was seven. Still, it’s hard not to remember him fondly through the lens of childhood memory.

So, it’s Ronald Reagan?

I don’t think so, not really.  Despite that picture up there of him riding some variety of velociraptor.

Then who?

See, that’s tricky. It’s easy to look back in history, and see problems – often huge problems – with any or all of the presidents. They were, after all, human beings with an interest in becoming (arguably) the most powerful single man in the country (and, particularly in the late 20th century, the world). That sort of man tends to have a number of less-than-admirable characteristics. Particularly if you don’t agree with his policies.

But, clearly, I need to make a choice. So, after doing some thinking, I’ll go (this time, at least) with Lyndon B. Johnson because of the things he accomplished as president.

Lyndon B. Johnson?

Lyndon Johnson was the 36th president of the United States, born August 27, 1908 near Johnson City, Texas. He was elected to the House of Representatives in 1937, served in the Navy in World War II, and then was elected to the Senate in 1948 (becoming the Senate minority Leader in 1953, and then the Senate Majority Leader in 1954). He served as John F. Kennedy’s running mate in 1960, and became president on November 22, 1963 after President Kennedy was assassinated. As president, he ran again and was reelected with 61% of the popular vote.

What did he do, to earn the position of my current favorite president? Well, here’s what his bio on Whitehouse.gov says:

First he obtained enactment of the measures President Kennedy had been urging at the time of his death–a new civil rights bill and a tax cut. Next he urged the Nation “to build a great society, a place where the meaning of man’s life matches the marvels of man’s labor.” In 1964, Johnson won the Presidency with 61 percent of the vote and had the widest popular margin in American history–more than 15,000,000 votes.

The Great Society program became Johnson’s agenda for Congress in January 1965: aid to education, attack on disease, Medicare, urban renewal, beautification, conservation, development of depressed regions, a wide-scale fight against poverty, control and prevention of crime and delinquency, removal of obstacles to the right to vote. Congress, at times augmenting or amending, rapidly enacted Johnson’s recommendations. Millions of elderly people found succor through the 1965 Medicare amendment to the Social Security Act.

Johnson also signed the Outer Space Treaty in January 1967, banning the use of nuclear weapons in earth orbit, on the moon, on other planets, and in deep space. He further signed the Nuclear Non-proliferation Treaty in 1968, committing the US to a policy of prohibiting the transfer of nuclear weapons to other nations, and began the negotiations that returned the Panama Canal Zone to Panama.

Pretty awesome, in my opinion, but not perfect. He dragged out the Vietnam War as well, and sent US Marines into the Dominican Republic to support the leader of a coup against the leaders of a coup against the democratically elected president of that country, when the people of that country rose up against the leaders of the coup. Neither of those things were what you’d call good things, but any president you care to name will have similar blemishes on his record – with the possible exception of William Henry Harrison, who didn’t manage to serve long enough to do anything particularly bad. As president, at least.  So, at this time, I’ll say Johnson still did some pretty good things for the country and say he’s my (current) favorite.

Fair enough. Now, what about dinosaurs?

Microraptor!

This is even trickier, because I love dinosaurs. All of them. Fortunately, I can narrow the field a little. The question, after all, states that the president has to ride the dinosaur, so I can rule out something like microraptor. The four wings are pretty cool, but it’s the size of a smallish chicken. You’d need hundreds of the things pulling a chariot, and that loses something quickly.

Actually, I tell a lie. It’s not tricky in the slightest. Because, no matter what, my favorite dinosaur is and always has been the Tyrannosaurus Rex.

Ah. The Tyrant Lizard King.

Oh, yeah.

Tyrannosaurus was always my favorite, from an early age. I mean, sure. I liked Triceratops and Stegosaurus as well, and I love some of the new dinosaurs that have been found over the past few decades, and Deinonychus caught my attention because my very first ever issue of National Geographic had a big article about the fossils of that brand new (to me, at least) dinosaur. But, at the end of the day, the idea of being a massive bipedal carnivore named the Tyrant Lizard King was awesome to my youthful mind and that feeling has never gone away.

Tell us about it.

Tyrannosaurus rex, based on recovered specimens, was a massive bipedal carnivore. Like, 12.3 meters (40 feet) long, 3.66 meters (12 feet) tall at the hips, and anywhere from 8.4 to 14 metric tons in weight. It was one of the largest land predators ever, and most paleontologists agree that it was an active predator that – like modern active predators – wouldn’t turn down the opportunity to chase other animals away from carrion and chow down as well. Their skulls are nearly as long as I am tall (I’m 6′ 5′ and their skulls were 5 feet long), and their teeth were foot long “lethal bananas”.

Well, maybe not every single tooth. But they still had some giant teeth.

They probably had feathers as well.

“I’m an utterly FABULOUS Tyrant Lizard King, baby!”

Yes, yes, I’m aware of the recent paper in Biology Letters (Tyrannosauroid integument reveals conflicting patterns of gigantism and feather evolution), indicating that they had scaly skin.  Early tyrannosauroids did have feathers, but the abstract states that “extensive feather coverings observed in some early tyrannosauroids were lost by the Albian”(the Albian being a stratigraphic layer and a period of time roughly 113 to 100 million years ago).  So, it’s unlikely at this point that T. rex was that fabulously fluffy thing in the image above, but the Smithsonian article on the paper (since the paper itself is paywalled) states that the authors indicate that T. rex still had plumage on it’s back.  Much more punk than New Wave, in other words. Still, I like to imagine them as 12 meter birds of paradise – which tells you everything you need to know about the way my mind works.

Which means..?

In answer to my son’s question, let’s saddle up Lyndon B. Johnson on a fabulous black and electric blue feathered Tyrannosaurus rex and do an elaborate ritual dance to celebrate the passage of the Civil Rights Act.

Are Roadrunners Really Real?

As a father, I believe it is my duty to see to my son’s education. So I’ve been exposing him to the classics. Specifically, Looney Tunes cartoons. I was flabbergasted when one of his friends stated he didn’t know who Bugs Bunny was. I mean, what is this world coming to?

So we’re sitting on the couch, eating popcorn and watching the Coyote blow himself up, and flatten himself, and fall off things in his endless quest to catch the Roadrunner. Dynamite and shotguns and anvils to the face. Good, clean family fun. Right? Right. And while we’re watching, my son asks the question. “Are roadrunners really real?”

“Well, yeah,” I tell him. “They live in the southwest.”

On the screen, the Roadrunner beep-beeps, and sticks his tongue out, and leaves the Coyote eating his dust.

“Are they that fast?” my son asks.

“I doubt it,” I reply. “But, let’s find out.”

 

He doesn’t think roadrunners are real?

It’s a sensible position, if you think about it. We weren’t watching Wild Kratts or Dinosaur Train or some other sort of educational program. We’re watching cartoons about coyotes getting 100,000 pound weights dropped on them. He’s seen coyotes on TV and at the zoo, so he can trust they’re real. But beeping birds that can outrun trucks? Yeah, he’s got a right to be skeptical.

Point taken. So tell us about roadrunners.

Sure. This is a roadrunner:

Specifically, that is Geococcyx californianus, also known as the Greater Roadrunner, a member of the cuckoo family (or, technically, a member of the Cuculidae family which includes roadrunners, cuckoos, and some other birds). As you can see, they don’t look much like the Roadrunner from the cartoons. They’re also a whole lot smaller than a coyote – coyotes in the American desert southwest range 15 to 25 pounds and get about 4 feet long, while the Greater Roadrunner gets up to 2 feet long and weighs up to 1 1/2 pounds. They’re also not blue and purple. They’re a mottled brown and white that blends in with the scrubland and desert they (mostly) inhabit – they can be found as far east as the Mississippi River, but you mostly find them in the southwestern United States and northern Mexico. Also, unlike the cartoon Roadrunner, they don’t beep. Instead, they make a sound that’d I’d describe as sounding like “wut-wut-wut-wut“.

The cartoons show the Roadrunner stopping to eat piles of birdseed, as part of the Coyote’s traps. If Wiley E. Coyote was hunting a real Greater Roadrunner, he’d be better off with a heap of bugs. Roadunners are primarily carnivorous, eating insects, spiders, scorpions, mice, other birds, lizards, and snakes (even rattlesnakes). They hunt by running up to their prey, grabbing it in their beak, and slamming it repeatedly against the ground until it stops refusing to be eaten. His trap might work on the Lesser Roadrunner (Geococcyx velox), though – they eat seeds. They als also roadkill, so they’d be attracted to the results of the Coyote’s inevitable failure (which could explain why it seems as if the Roadrunner keeps coming back to gloat…).

How fast is a roadrunner?

Fast. They’re fast.

Roadrunners can fly, keep this in mind. They’re just not much good at it. They’ll fly to get up to their nests, when sprinting downhill, and to escape from predators, but they can’t maintain altitude for more than about a minute. They’re much better adapted to running, and can hit speeds in excess of 20 miles per hour – an impressive feat for a tiny bird – fast enough to catch dragonflies and hummingbirds on the wing. They’re even fast enough to prey on rattlesnakes, one of the few animals that can.

That’s pretty fast. Could the Coyote catch one?

The answer to that is a solid “maybe”, because it turns out that coyotes are fast. They’ve been seen to sprint at up to 45 miles per hour, and can run at up to 20 mph over distances of a mile or two. That speed drops to about 10 mph if they’re running over longer distances. I couldn’t find any details on how long a roadrunner can maintain its 20+ mph running speed, but the videos I’ve watched don’t show them slowing down for much of anything. So, like so many things in nature, it comes down to circumstances. In a flat-out race, Coyote would finally be dining on Roadrunner. But the roadrunner would be bobbing and weaving and trying to dodge until the exhausted coyote couldn’t keep sprinting, and then (assuming it isn’t lodged in the coyote’s jaws) keep running.

Huh. Anything else?

Yeah. There’s one cartoon in which, in an effort to catch the Roadrunner, the Coyote dons a “female roadrunner costume”. The Roadrunner is unimpressed, running up with a sign that reads “No thanks, I’ve already got a date,” before beeping and sprinting off. This, it turns out, is actually fairly accurate. Well, except for the crosdressing coyote. See, roadrunners are monogamous. The mated couple breeds in the sring, lays anywhere from 2 to 12 eggs, and take turns incubating the eggs. It’s not all happy domesticity, though. The fledglings will crowd out any late-hatching runts, which are then generally eaten by the parents.

Also, along with pooping and peeing all at once, roadrunners have an extra adaptation to help conserve water. They excrete waste salt through their tear ducts, as a way of conserving water. As a result, they almost never need to drink – all of the fluids they need come from their prey.

What Are Cataracts?

This question came up because my son’s babysitter is fostering a blind dog – an adorable little black poodle with milky white eyes named Rosie.

Seriously. How cute is that?

My son and his babysitter’s two children love her and spoil her and carry her around, and they describe her as having “moon eyes” because they sort of look like full moons. The Peppermint Pig Animal Rescue was going to get her eyes operated on to remove the cataracts, but it turns out she also has detached retinas. So the surgery wouldn’t really change anything for her.

We were talking about the dog, and the news, and my son asked “what are cataracts?” Because we’d used the word and he didn’t know it.

“It’s what makes Rosie’s eyes white,” my wife replied.

“But what are they?” he replied.

“It’s…” My wife thought for a second. ‘It’s like a film on her eyes, that she can’t see through.”

“But why are they called that?” my son persisted.

So. What are cataracts?

This. This is a cataract.

I’ll be honest, here. I don’t actually know. My wife’s explanation seemed as good as any, and I think I always sort of assumed that they were something like scar tissue. But, like with so many other things, I’ve never really stopped to ask what they were or what causes them. So, since my son asked, it’s time to change that.

Definition

Merriam-Webster, my go to for dictionaries thanks to a handy app, gives two definitions for “cataract“:

  1. [Middle English, from Medieval French or Medieval Latin; Medieval French catharacte, from Medieval Latin cataracta, from Latin, portcullis] : a clouding of the lens of the eye or of its surrounding transparent membrane that obstructs the passage of light
  2. a obsolete : waterspout
    b : waterfall; especially : a large one over a precipice
    c : steep rapids in a river the cataracts of the Nile
    d : downpour, flood cataracts of rain cataracts of information

I’m guessing that the medical term is used explicitly because of the “portcullis” meaning in Latin, since cataracts more or less block light from entering the eye. The Online Etymology Dictionary seems to agree, so that makes me feel better.

The medical condition

Multiple online sources (the Mayo Clinic and the American Academy of Ophthalmology to name just two) agree with the Merriam-Webster definition. Cataracts are a clouding of the lens of the eye. This can result in blurry vision, seeing double, light sensitivity, having trouble seeing well at night, needing more light when reading, seeing “halos” around lights, and seeing bright colors as faded or yellowed. They are the most common form of vision loss in people over the age of 40, and the single most common cause of blindness in the world (in the US alone, more than 22 million people have cataracts).

Aging is the most common cause of cataracts, because the proteins in the lens of your eye will denature over time. This is not a good thing, because your lens is made of living cells and denatured proteins disrupt the cells and can even kill them. Diabetes and high blood pressure can accelerate the process, as can ultraviolet light (UVB, specifically) and other radiation and blunt trauma to the eye. There is a genetic component to the development of cataracts as well, particularly if someone develops them in childhood or as young adults. These aren’t the only causes, of course. Just the most common.

The most common forms of cataracts are subcapsular, nuclear, and cortical. Subcapsular cataracts start at the back of the lens, and are most common in diabetics and people taking medical steroids. Nuclear cataracts start in the center of the lens, and are most commonly associated with aging. Cortical cataracts start at the edge of the lens and work inwards ina “spoke-like fashion”. There are also congenital cataracts, which you are born with or develop during childhood – usually due to your genes or some form of infection or trauma.

Treatment

Ultimately, the only treatment for cataracts is to remove the existing lens and replace it with an artificial lens called an intraocular lens that matches the prescription (if any) that you need for your glasses. The intraocular lenses come in a wide variety of different types, and if you need one you should consult with your ophthalmologist to see which ones make the most sense for you.

Surgery is generally considered a last resort, though. As long as the cataract symptoms aren’t bothering you, and the problems with your vision can be corrected with glasses, there generally no need to undergo surgery. Cataract surgery is considered pretty routine, but the only really risk-free surgery is one that you don’t have.

Hang on, hang on. This is all about people. Didn’t this start with a dog?

Yep. But cataracts aren’t limited to humans. It’s a condition caused by disruption and damage to the lens of the eye, so any animal with an eye with lenses can develop cataracts. There’s a lot of information on the internet about dog cataracts, and mentions of cats. One veterinarian stated that they are “the most common cause of blindness in dogs, and can also affect people or any species of animal”. Like humans, animal cataracts can develop from age, diabetes, trauma, genetics, or something called Progressive Retinal Atrophy – the name for a cluster of generic disorders that cause the retina to degenerate. Animal cataracts can be treated in the same way as human cataracts. Progressive Retinal Atrophy has no treatment, though.

Impaired vision and even blindness aren’t a death sentence for a house pet, though. Rosie gets around just fine, as long as you don’t move her food and water dishes and rearrange the furniture a whole lot. So if you live in the Cincinnati area and want to adopt an adorable little blind dog (or another animal), contact the Peppermint Pig Animal Rescue. They’ve got a lot of animals looking for a loving new home.

What Fossils Did I Find?

Way back in February, I wrote about the fossils my son found. At that time, I promised him I’d do some research and find out what kind of fossils they were. To recap, here’s what they looked like:

Time passed, and he asked other questions, and I got busy studying for a certification test at work (which is why I’ve been so quiet the past few months). But finally, since I’ve had a chance to catch my breath, it’s time to answer a question: what, exactly, are those fossils?

Well?

My primary source for this is Identification Guide for Common Fossils of the Cincinnatian. Based on this guide, most of the fossils appear to be Brachiopods, most likely some species of Cincinnetina (since they’re common in the region) – from the pictures in the guide, though, they could be Platystrophia ponderosa. The point is, they’re certainly brachiopods, and they’re around 480 to 440 million years old.

To tell you the truth, my son was disappointed that he didn’t find a Tyrannosaurus Rex.  That wouldn’t be particularly likely, however, for a few reasons.  The first being that T. Rex didn’t live 440 million years ago, and the second being that if T. Rex did live 440 million years ago in Cincinnati he would have drowned.  Because Cincinnati was under water.

Map courtesy of The Paleomap Project

So, no Tyrannosaurs here.  Certainly not in the strata that was laid down on his brachiopods.

And what, exactly, is a brachiopod?

Well, Wikipedia says that brachiopods are:

…a group of lophotrochozoan animals that have hard “valves” (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, while the front can be opened for feeding or closed for protection.

“Lophotrochozoan” animals are a clade of bilaterally symmetrical animals with cillia around their middle, if that helps.

Brachiopods are related to mollusks and annelid worms (earthworms and leeches). There are around 330 living species. There were a whole lot more of them back in the past, with the greatest diversity of Brachiopods occurring in the Devonian. The Permo-Triassic mass extinction crushed a lot of that diversity, and it has never fully recovered.

Modern brachiopods feed by sucking water in through their sides, using their cilia to trap particles of food, and then expelling the water and any waste products through the front. They absorb oxygen through their skin, and have colorless blood, and some modern species can live over 30 years (assuming they aren’t eaten).

Case closed, right?

Well, except for this strange little thing:

Uhm. What is that?

I have no idea. I’m pretty sure that’s not a brachiopod. Not unless we’ve got the shell end-on, and it also folded in a pretty dramatic fashion. After some digging, I four possible candidates. Here they are.

1. It’s just a rock. Needless to say, I find that boring. It is the null hypothesis, but I don’t think it’s accurate. after all, the color resembles that of the other fossils in the piece of stone my son found. So, although it’s certainly possible, I don’t think it’s correct.

2. It’s a piece of an Isorophus cincinnatiensis. This might be a reach, because it would make it a fragment of an arm of a 440 million year old echinoderm. Pros for the argument are that it’s from the region, it’s about the right size, and it looks kind of like the arm seen in this picture. Cons for the argument include the fact that it doesn’t look a whole lot like the arm in that picture.

3. It’s a bit of coral. I couldn’t find any pictures of coral that curves like that, but that doesn’t mean they don’t exist.

4. It’s something I can’t identify. Yes, yes, that’s an utterly lame hypothesis. But I’ve got nothing else, and I’m pretty sure it’s some flavor of fossil. So, I’ll probably just leave it at that. Unless someone reading this happens to know what that might be.

Why Do Birds Poop And Pee At The Same Time?

I don’t know if my son was watching a nature program, or if he’d been talking about this at school, or what. All I know is that, as we were walking into the condo one day, he suddenly stops and points. “Look dad! An owl!”

I stare along the side of the building, wondering which of the trees he’s talking about. Or is it perched on a balcony, maybe? “I… don’t see it,” I say.

“It’s right there!” he exclaims, pointing. “Oh, no. It’s a squirrel. Look, dad! A squirrel!”

“I don’t see it,” I tell him. “But my eyes aren’t as good as yours.”

He nods at that. “Dad?”

“Yes, son?”

“Why do birds poop and pee at the same time?”

…that is not what I thought he was going to ask.

Do they poop and pee at the same time?

This seems like the first place to start, because I’m not at all certain they do. I mean, sure. I’ve heard this before. But it wouldn’t be the first time I’ve found that “received wisdom” is wrong and that something I thought was true wasn’t true. However, in this case, it seems that received wisdom is correct.

This is going to be more than I wanted to know, isn’t it?

Hey, you’re the one reading this.

Pretty much all animals produce ammonia (NH3) during digestion. It’s a side effect of the breakdown of proteins, which all animals need whether they’re carnivores or herbivores. Ammonia is, however, toxic (doses of 350 mg/kg of weight can kill), which means that animals have to deal with it in some fashion. And by “deal with” I mean “get rid of”.

Generally speaking, mammals will mix it with some of the waste carbon dioxide (CO2) they produce through breathing and convert it into urea (CO(NH3)2) – a far less toxic chemical (the lethal dose is 8,471 mg/kg) that also happens to be water soluble. Mammals then, generally speaking, expel it (along with other waste chemicals) in the form of urine.

Birds don’t do this. Birds, it seems, don’t even have bladders.

Sigh. Tell me more.

To start with, most birds convert ammonia into uric acid (C5H4N3O3, lethal dose around 5040 mg/kg) instead of urea. The other thing they do, which is the reason why they simultaneously poop and pee, has to do with anatomy. See, bird excretory systems work a lot like lizards. They have kidneys, of course, and ureters (the ducts that allow urine to leave the kidney). However, they lack bladders. Instead, they have something called a cloaca – a multipurpose organ that serves as both the reproductive and excretory organ.

The urine enters the cloaca through the ureters, where it is pushed up into the large intestine. The large intestine re-absorbs much of the water content, allowing the urine to be concentrated into a thick paste before it is passed by the bird. since uric acid dries white, this lends bird droppings their distinctive appearances.

So, in short, birds poop and pee at the same time because of evolution.  And because they aren’t equipped to poop and pee separately.

Why Do Sharks Eat So Many People?

“Dad?” my son asked as we got out of the car. “Why do sharks eat so many people?”

I assume he’d seen something about sharks at school, but the question still came out of nowhere. Thirty seconds before, he’d been telling me about his school’s Mardi Gras party and asking me if I felt better (because I’ve been sick, which is why this article still isn’t looking at the fossils he found). So, I put my mind to it. “I don’t think they do,” I answer.

“They don’t eat people?” he responds, sounding skeptical.

“Well, they can,” I concede. “But they don’t eat people all that often.”

“Why not?” he asks, and I swear he sounds disappointed.

“Well, a lot of them are kind of small. And we aren’t the kind of things they normally hunt.” I’m trying to remember shark facts, now. “Most of them are probably just wondering what we are, and people get scared of them and think they’re attacking.”

“Why do people get scared?” he asks.

I shrug. “Why did you get scared of them, when we went to the aquariam?”

“Because they look mean!” Then he grabs my hand. “Since you’re not feeling good, can we take a break and play Star Wars?”

Do sharks eat a lot of people?

This is one of those questions where I really hope I told my son the right thing, because I was working from half-remembered articles I’d read years ago, and memory is a fickle, tricky thing. Fortunately, it turns out that the University of Florida maintains the International Shark Attack File (ISAF), which they describe as “the longest running database on shark attacks, has a long-term scientifically documented database containing information on all known shark attacks, and is the only globally-comprehensive, scientific shark attack database in the world”.

Before we dive into the numbers, though, it’ll be important to define two terms the ISAF uses: provoked attacks and unprovoked attacks.

  • An unprovoked attack is edfined as “incidents where an attack on a live human occurs in the shark’s natural habitat with no human provocation of the shark.”
  • A provoked attack, on the other hand, usually occurs “when a human initiates physical contact with a shark, e.g. a diver bitten after grabbing a shark, attacks on spearfishers and those feeding sharks, bites occurring while unhooking or removing a shark from a fishing net, etc.”

The ISAF reports that 2016 was a pretty typical year, with a total of 150 alleged shark attacks. Out of those 150 attacks, here’s how the results broke out:

  • 81 were classified as unprovoked attacks (53 total in the United States, 43 of which were in Hawaii).
  • 37 were classified as provoked attacks.
  • 12 were sharks biting boats (aka “boat attacks”).
  • 1 was a shark eating part of an already dead human cadaver.
  • 12 had insufficient evidence to prove a shark attack.
  • 7 were determined to be attacks by other marine animals (including a barracuda and an eel).
  • 5 were determined to be abiotic injuries (that is, an environmental injury – scraping coral or rock, for instance).

So, in the fairly typical year of 2016, there were 118 total shark attacks on humans (131 if you count the boat attacks and the scavenging). 2015, by contract, hit 98 unprovoked shark attacks- the highest yearly total on record. On average, shark attacks result in 6 to 8 fatalities per year (depending on what period of time you average out), but 2016 only had 4 shark attack fatalities. Statistically, surfers are most likely to be attacked 958% of the total), followed by recreational swimmers and waders (32.1% of the attacks).

That’s not a lot of attacks, is it?

No, not really. In fact, there’s a whole lot of animals that are much more likely to kill you. According to the BBC, venomous snakes kill an estimated 50,000 people each year, rabid dogs kill an average 25,000 people each year, crocodiles kill an estimated 1,000 humans per year, and hippos kills an estimated 500 people per year. All of which makes the paltry 6-8 shark kills each year pretty tame.

friendly-shark

Still, it’s probably best not to do this unless you know what you’re doing.

The ISAF provides some other interesting comparisons. The odds of dying from a shark attack are 1 in 3,748,067. Fireworks are about 11 times more lethal (odds of death: 1 in 340,733), sun and heat exposure are 273 times more lethal (odds of death: 1 in 13,729), and the flu is 59,664 times more likely to kill you (odds of death: 1 in 63).

Why do shark attacks get so much attention, then?

Rarity, in my opinion. Rarity and shock/

See, we notice things that appear out of the ordinary. According to the CDC, heart disease is the leading cause of death in the United States (614,348 deaths in 2014), followed by chronic lower respiratory diseases (147,101 deaths), accidents (136,053 deaths), stroke (133,103 deaths), Alzheimer’s disease (93,541 deaths), diabetes (76,488 deaths), and influenza and pneumonia (55,227 deaths). Most of those get no attention at all, unless they’re really spectacular or they happen to someone famous. But death by animal attack? That’s unusual, particularly in the United States. And particularly because we like to think we’re outside the food chain. Homo sapiens sapiens is, realistically, the ultimate alpha predator and one of the dominant environmental forces on the planet. It’s unsettling to be reminded that we’re still animals, and that we can still become prey.

Also, sharks inhabit an alien environment that we can only meaningfully visit with the benefit of technology. A wolf or bear attack happens on dry land, so the surroundings aren’t inherently hostile to us. But sharks? A shark could kill us with their own environment, even if the bite isn’t fatal. So, they seem frightening.

Just in case I am one of the unlucky ones, any tips?

Actually, yes. Here’s what the ISAF says: “If one is attacked by a shark, we advise a proactive response. Hitting a shark on the nose, ideally with an inanimate object, usually results in the shark temporarily curtailing its attack. One should try to get out of the water at this time. If this is not possible, repeated blows to the snout may offer a temporary reprieve, but the result is likely to become increasingly less effective. If a shark actually bites, we suggest clawing at its eyes and gill openings, two sensitive areas. One should not act passively if under attack as sharks respect size and power. “