December 12, 2025 • 26 mins
On a rainy, windy day, But Why hopped on a ferry and headed to Governors Island in New York City with one thing on our minds - oysters! We met up with Mike McCann of the Billion Oyster Project to learn more about these very special bivalves. How do they get their shells? How long do they live? What do oysters eat and who eats them? Why do people eat oysters without cooking them?
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Jane (00:20):
This is But Why, A Podcast for Curious Kids, from Vermont
Public. I'm Jane Lindholm. Onthis show, we take questions
from curious kids all over theworld, and we go out and find
answers. This fall, on anexceptionally rainy afternoon,
the But Why team drove over toNew York City to visit a place
(00:40):
called Governor's Island. We hadto take a ferry to get there. We
went all the way to Governor'sIsland in the rain because we
wanted to learn about a veryspecific project and a very
specific animal. See if you canguess what it is! These animals
live in salt water. They'repretty small. Most species could
(01:03):
fit in the palm of your hand.When they're an adult, they
filter as much as 50 gallons ofwater per day per animal,
straining out pollutants andcleaning the environment around
them. They have no brains and noeyes, but they do have a heart.
And they're famous for makingpearls. That last fact might
(01:24):
have given it away. We'relearning about oysters today.
When you think about New YorkCity, oysters probably aren't
the first thing that springs tomind. But over a hundred years
ago, New York was known as theoyster capital of the world. You
could buy oysters from carts allacross the city, and oyster
(01:44):
shells were used in buildingconstruction. The oysters
themselves helped keep New YorkHarbor clean. Over time, though,
the oyster population declined,a result of over harvesting and
water pollution. And when NewYork Harbor lost its oyster
reefs, it also lost a lot ofbiodiversity--the wide variety
(02:05):
of plant and animal species thatmake a healthy ecosystem--and
that underwater environmentbecame more bare, less full of
crags and reefs and differentkinds of textures, which made it
less resilient and less able toabsorb floods and erosion.
But a group of young people,scientists and teachers have
(02:26):
been working for the last decadeto restore oysters to the harbor
in the hopes of reversing someof those negative consequences.
The project is called theBillion Oyster Project, and it's
headquartered on Governor'sIsland, which is why we were
there. When we got off theferry, we weren't sure exactly
where we were supposed to go,but then we saw a tall man drive
(02:49):
up in a golf cart and wave atus.
Okay, tell me who you are.
Mike McCann (02:52):
My name is Mike McCann. I'm Director of Science
and Research at the BillionOyster Project.
Jane (02:56):
We piled into Mike's golf cart, and he drove us to the
other side of the island, wherethere was a giant pile of empty
shells.
Describe these shells, becauseI'm looking at them and some of
these shells are really big.Some of these shells are really
small. Some of them are kind ofpurpley. This one is huge
compared to the other one. Sowhat are all these shells?
Mike McCann (03:17):
So 99% of the shells here are from oysters. So
we should back up and say,what's an oyster, right? An
oyster is an animal. It's amollusk.
Jane (03:25):
What's a mollusk?
Mike McCann (03:27):
An animal that has a shell, that makes its own
shell. Among the mollusks youprobably know: snails and slugs,
but octopus and abalone? Allthese things are mollusks. And
there's a branch of the molluskcalled the bivalves, and that's
where oysters live. So that'smussels and scallops and clams
(03:49):
and oysters. So they have bi,valve--two. That's what that
root bi means, and valve likethese two shells, which you can
maybe hear me clicking together.
Jane (03:58):
What kind of oyster shells are you holding?
Mike McCann (04:00):
So from the Gulf all the way up to Maine, up into
Nova Scotia, we have one singlespecies of oyster. Scientists
call it Crassostrea virginica,the common name, Atlantic
oyster, or Eastern oyster. Somost of this pile is of the
Eastern oyster.
Benjamin (04:20):
Hi, but why? My name is Benjamin. I am eight years
old, and I from Long Beach,California, and I want to know,
how do oysters make theirshells?
Mike McCann (04:33):
Yeah. So oysters are really special. Like all
these bivalves, they producetheir own shells. So you might
be familiar with a hermit crab,but a hermit crab doesn't make
its own shell. It actuallystole--it's a crab that stole it
from from a snail. So oystershave this very special tissue
called their mantle. And it'ssort of a very thin tissue
(04:56):
that's at the edge of theirbody. And they can take minerals
that are in the water, primarilycalcium, which is, you know, in
our teeth and in our bones. Sothey're taking calcium,
extracting it from the water,which there's plenty of calcium
in sea water, and they mix itwith protein. And then they can
secrete--layer by layer, thatmantle tissue can sort of build
(05:18):
more and more layers of shell.So as their body's growing,
their shell can grow around it,
Jane (05:24):
And does their shell grow for their entire life?
Mike McCann (05:26):
Yeah, that's right, they have a shell when they're a
baby, swimming free, swimming inthe water for those two to three
weeks, and then that shell iswith them for life. So unlike a
crab, who you may know that acrab can molt its exoskeleton,
where they basically climboutside of their hard shell. An
oyster never does that. It nevermolts. It never sheds that
(05:48):
shell. It has it for life.
Bennett (05:50):
My name is Bennett. I'm seven years old, and I live in
Grafton, Massachusetts. How longcan oysters live?
Mike McCann (05:57):
In New York City, many of our oysters, we've
restored reefs, and they mightbe seven or eight years old on
those reefs. Occasionally 10,12. I think we've heard from
other harbors, other estuaries,20 years old.
Jane (06:11):
20 years old. So you can have an oyster that's 20 years
old.
Mike McCann (06:14):
Yes.
Jane (06:14):
Old enough to go to college.
Mike McCann (06:15):
That's right.
Jane (06:16):
So if I look at one of these shells here, I can see
kind of rings on the shells.Does that tell me anything about
how old the oyster is?
Mike McCann (06:27):
Not precisely. You can get a general feel when you
see those sort of ridges andbreaks that there was probably a
period of rapid growth. But it'shard to infer. Like it's not as
precise as a tree ring, ifyou're familiar, so you can sort
of tell when summers and wintersare if you slice a tree trunk in
cross section. An oyster shell,it's a little bit less precise.
Jane (06:50):
I was trying to concentrate on Mike's answers
about what oysters are and howlong they live, but the giant
pile of shells in front of mewas really distracting. It was
just so big. If I had climbed upon it, I bet I could have seen
all of Governor's Island.
Mike McCann (07:08):
These are some good ones.
Jane (07:09):
Okay. How many shell pieces do you think there are? A
billion?
Mike McCann (07:15):
Oh, boy, that's a tough question. We have
collected 3 million pounds ofoyster shells from New York City
restaurants since our program'sbeen around. And you can imagine
each pound probably has a fewhundred or a hundred, so we
could do some math, 3 billion.
Jane (07:36):
Yeah, well over a billion.
Mike McCann (07:37):
Yeah.
Jane (07:38):
But wait, it's called the Billion Oyster Project, not the
3 Billion Oyster SHELL Project.So what's going on with all
these shells, and where do thebillion oysters come in? Stay
tuned.
BREAK (07:49):
BREAK
Jane (07:51):
This is But Why. I'm Jane Lindholm, and today we're
learning about oysters fromBillion Oyster Project's Mike
McCann on Governor's Island inNew York City. When we visited,
Mike had driven us across theisland from the ferry dock in
his golf cart to gaze inamazement at a pile of about 3
billion oyster shells. Theseshells, which also included some
(08:12):
clam and scallop and othermollusk shells, come from
restaurants all over New YorkCity. After people are done
eating their shellfish dinners,the restaurants give the shells
to Mike and his team, and theshells wind up on that pile.
Mike McCann (08:26):
This is sort of the raw materials, the building
blocks, for an restored oysterreef, or created oyster reef,
where humans get involved. Sowe've got tens of thousands of
pounds of oyster shell. It'sbeen collected from restaurants
all over New York City.
Jane (08:42):
Those are all oyster shells. I'm on a pile. I could
climb up this, and I would be,you know, queen of the mountain
if I climbed it.
Mike McCann (08:51):
And so these are going to spend about a year
outside curing. So there'sprobably, you know, little
specks of oyster tissue andother things on it. So we leave
them out here, expose theelements, so they get really
nice and clean. Then we cleanthem up, we crush them up, and
we combine them with ecoconcrete, and we build what are
called reef balls.
Jane (09:11):
It turned out those reef balls were actually right behind
us, so we turned around andwalked over to them.
Mike McCann (09:18):
So they look like sort of concrete domes with
holes maybe the size ofvolleyballs in it, and so that's
made of oyster shell, ecoconcrete, which is special blend
of concrete that oysters andother marine life really likes.
And this will be the sort ofbase of the reef.
Jane (09:39):
If you were to look at one of these, it looks kind of like
a very, very large plant pot,but the way they're stored here,
upside down. And it's got holesin it. So it's a little bit like
maybe if you use a colander toclean your raspberries or to
drain your pasta, it's kind oflike a colander for a giant.
Mike McCann (09:58):
And it weighs about 500 pounds, so definitely a
giant-size colander.
Jane (10:03):
Okay, so this is made up of eco concrete and oyster
shells?
Mike McCann (10:08):
And that's not enough to get a reef right. We
could put these in the harbor,and, you know, some fish would
be interested in maybe startbuilding a home around it, but
we need to introduce livingoysters. So also on Governor's
Island, we have what we call ourremote setting facility. And
these are giant shippingcontainers, big steel cubes that
(10:30):
we've retrofitted to hold thereef balls. And then we
introduce baby oysters. We canbuy them from professional
hatcheries, where we'll import70 million oysters at a time, 70
million, and we'll add those tothese shipping containers with
about 40 reef balls. And thenthose oysters, we're basically
(10:51):
going to recreate that processthat they'd be doing out there
in the harbor, where they'dspend a couple of days, find
their home on the reef balls.And then that can be the mobile
unit that we can then deploywherever we want, into New York
Harbor.
Jane (11:05):
Let's recap. The Billion Oyster Project takes billions of
shells from people who've beeneating shellfish for dinner. It
grinds them up and mixes themwith eco concrete, and then
turns those shells and theconcrete into these structures,
these reef balls, that they thencan drop into New York Harbor to
start forming the infrastructurefor oyster reefs. They add
(11:28):
millions of baby oysters to thereefs, and those tiny oysters
swim around and latch onto thereef balls and start building
their shells out of the calciumin the structures. As the
oysters get older and bigger,they stay latched onto the
reefs, and other animals beginusing those big, open structures
for safe habitat as well.
Cecily (11:49):
Hi, my name is Cecily. I'm 10 years old. I live in
Winnipeg, Manitoba, and myquestion is, what do oysters
eat?
Mike McCann (11:57):
Oysters eat algae, so they don't eat the big leafy
green seaweed kind of algae thatyou might be familiar with. But
in our harbor and in mostharbors, there's lots and lots
of microscopic algae calledphytoplankton. So these are
single celled algae that arereally abundant in huge numbers,
(12:19):
and the oysters filter thosemicro algae out of the water.
Jane (12:24):
They eat algae, and that helps filter the water. But how
are they actually doing that?
Mike McCann (12:28):
Yeah, it's an amazing process. Inside their
body, between the two shells, isa special tissue called the
ctenidium, and it--
Jane (12:38):
Can you spell that?
Mike McCann (12:39):
C, t, e, n, i, d, i, u, m. It's hard to spell out
loud.
Jane (12:46):
I did not think it was gonna start with a C!
Mike McCann (12:48):
Yeah, it's a tricky word. It comes from a Greek word
for comb, and it looks like atiny little comb. There's all
these sort of branches like youwould for the comb you use in
your hair, but they're coveredin cilia. And these are these
really tiny sort of hair-likecells, and those cilia just are
constantly beating, pulling thewater in. And this organ is
(13:10):
amazing, because the oyster canactually choose the particles
that it wants to eat and choosethe particles that says, "Nah,
that's not food. I don't want toeat that." And so on this
cone-like structure, there's allthese sort of conveyor belts,
and they can actually moveindividual microscopic algae
cell and move it to their mouth.And then, if there's, you know,
(13:31):
say, a piece of plastic, theymight say, "Ugh, let me get rid
of that." And they they bind itup with some mucus, and it comes
out as pseudo feces.
Jane (13:40):
Pseudo means fake. Feces means poop. So it's fake poop?
Mike McCann (13:44):
It never went through their body, but it kind
of looks and feels a lot likepoop.
Jane (13:50):
So if they're filtering bad stuff out and then putting
it back into the water, how isthat cleaning the harbor?
Mike McCann (13:57):
Right. So there's two ways that they can either
bind up or transform pollutants.So in that process of creating
pseudo feces, what they're doingis sort of taking it from the
water and depositing it andburying it into the sediment. So
it stays there, in many cases,and that's a good thing. But for
some of the pollutants, they canactually get rid of it entirely.
(14:20):
So in many estuaries, too muchnitrogen is one of the biggest
pollutants. 70% of the air webreathe is nitrogen. But too
much nitrogen in the water isactually a really bad thing. It
can cause algae blooms and allthese other problems in an
estuary. But the microbialcommunity that lives in and
around all those nooks andcrannies on the oyster reef
(14:42):
actually take that nitrogenthat's dissolved in the water
and convert it into nitrogengas, which then goes into the
atmosphere, where it's perfectlyfine for nitrogen gas to be. So
they're transforming andremoving nitrogen, one of the
biggest estuarine pollutants. Soan individual oyster can filter
tens of gallons, maybe up to 50gallons of water a day. That's
(15:03):
just one big, full grown oystercan really just move a lot of
water through its body and cleanit up.
Jane (15:10):
So what would a billion oysters do?
Mike McCann (15:12):
A billion oysters could filter, you know, a good
chunk of New York Harbor in afew days.
Jane (15:17):
That's pretty awesome. And you plan, or hope, to be able to
put a billion oysters into NewYork Harbor by...
Mike McCann (15:24):
2030.
Jane (15:25):
2030. Whoa. Okay, so you've got five years.
Mike McCann (15:28):
We're feeling optimistic.
Jane (15:30):
How many are you doing a year?
Mike McCann (15:31):
So, so far, we have returned 150 million oysters. So
we're currently doing about 25million a year. But in the next
year, our facility is going toexpand to do about 100 million a
year.
Jane (15:49):
Good, because you're gonna have to get speedier.
Mike McCann (15:49):
Gotta get moving. Yeah.
Aurora (15:50):
My name is Aurora. I'm five years old. I'm from
Brownsville, Texas. Why dooyster live in the ocean, but
not in the lake?
Mike McCann (15:59):
Oysters live in oceans because that's where
their mom and dads lived. Sothat's where most mollusk
species originated. So if you goback tens of thousands, hundreds
of thousands of years ago, whenmollusks originated, it was in
the oceans. And we know somemollusks, like snails and slugs,
(16:21):
have made it onto land. Somehave made it into freshwater
ponds, but the majority ofmollusks live in the ocean, and
it's a really tricky thing tolive both in the ocean and in
the fresh water, because all ofyour cells in your body need to
be able to osmoregulate, whichis basically balance salt and
(16:42):
water. And so you could really,for most organisms, only
specialize in one place, becausethe way your cells are trying to
balance, they're saying, "Hey, Ineed to get rid of excess salt."
Or "I need to get rid of excesswater." Most species have
adapted to just one of thoseenvironments, and not both.
There are a few exceptions, youknow, some fish species can span
fresh water and salt water, butit's a really hard task to do.
Caden (17:05):
My name is Caden. I'm four years old, and I live in
Rockland, Massachusetts. Wheredo oysters go in the winter?
Mike McCann (17:16):
So oysters, except for when they're a baby, can't
move, so they are stayingcemented in place on that reef
that they chose when they werejust two or three weeks old. So
what that means in a place likeNew York City, where it gets
really cold in the winter, thewater goes down to 33 degrees
Fahrenheit, that means they'restaying in place and they are
(17:40):
basically slowing theirmetabolic rate, and they're
living off all the food they ateall summer and all of those
reserve energy stores so anoyster can survive. And you
know, ice cold water.
Jane (17:52):
For 20 years!
Mike McCann (17:53):
For, well, you know, one winter at a time, for
20 years, yes.
Bennett (17:58):
My name is Bennett. I'm seven years old, and I live in
Grafton, Massachusetts. Myquestion is, what animals eat
oysters?
Mike McCann (18:07):
So oysters are food for other animals, and that's a
pretty natural and normal thing.So there are crabs that'll eat
oysters, like blue crabs and mudcrabs. There are fish, like the
oyster toadfish, it's gotspecial crunching teeth that can
break through shell. There'ssnails...
Jane (18:26):
Can you just pause on the oyster toadfish? Because first
of all, it has a fantastic name,but also it is a weird-looking
fish.
Mike McCann (18:33):
It looks kind of grumpy. It sounds like a toad.
That's how they communicate witheach other, and it loves to live
on oyster reefs. It's one of thereef residents. It sort of makes
their home on these reefs. Morepredators, oyster predators: so
we said crabs, we said fish.Also snails, like the oyster
(18:54):
drill, which is a snail that'ssmaller than a quarter, but it's
got a special mouth part thatcan drill holes into oysters,
and then they slurp out theinsides.
Jane (19:04):
So even though it's a fellow bivalve, it isn't like,
"Ah, you're cool."
Mike McCann (19:08):
There's no loyalties from the oyster drill.
And then sponges. There's asponge called a boring sponge,
boring not because it'suninteresting, but boring
because it bores holes into theoyster shell. So if we look
through that pile, we couldprobably find some oyster shells
that have had some boringsponge, looks like Swiss cheese.
Jane (19:27):
Oh, I think I saw one of those. And then, of course,
humans eat oysters.
Mike McCann (19:31):
Yeah, that's right. Oysters are, I think, famous
because of the fact that they'rereally delicious, and many
people love to eat them. Andthat's the source of these
oysters shells that we have hereat the shell pile. These all
came from New York Cityrestaurants where diners enjoyed
a dozen oysters on a night outon the town, and then they end
up here to be restored back toNew York Harbor. New York City
(19:53):
was, you know, once the oystercapital of the world in terms of
how many oysters were grown andproduced and harvested here and
shipped. Across the UnitedStates, over to Europe. Most
oysters at one point in timewere coming from these waters in
the 1800s but it's been 100years since we've had that.
We're not trying to restore apopulation of oysters in New
York City to eat anytime soon,our water is still much too
(20:15):
dirty for that.
Jane (20:17):
So that's one thing that you should be aware of when
you're thinking about eatingoysters, is that they are
incredible filterers. So youwant to make sure you're eating
oysters from clean water, notplucking one out of polluted
water.
Mike McCann (20:28):
Yeah, that's right. Oysters really reflect the water
that they're in. So you know,there are many places in New
York, not in New York City, ifyou go out in Long Island, where
the state has said these watersare clean and you can grow and
harvest and farm oysters here.
Lucy (20:43):
My name is Lucy. I'm six years old. I live in Guelph,
Ontario. Why is it safe to eatoysters without cooking them?
Mike McCann (20:55):
Yeah, so it's only safe to eat oysters if they've
come from clean water. And anyoyster you see in a store, in a
grocery store, a fish market, arestaurant, has come from waters
that have been designated safefor harvest, so oysters that
have been harvested from cleanwater and have been kept cold
(21:15):
are going to be safe to eat.
Jane (21:17):
So you should always check with your adult and maybe check
where you're buying the oystersfrom.
And don't harvest them from NewYork City.
Also, because we want theoysters to stay here, because
they're doing important work.
Mike McCann (21:28):
That's right.
Sarah (21:29):
My name is Sarah. I'm from Portland, Oregon, and I'm
eight years old. How do oystersmake pearls?
Jane (21:36):
Do you know what a pearl is? You might have seen pearls
on someone's earrings or anecklace. When you see them on a
piece of jewelry, pearls aretypically round and a lot of
them look milky white and shiny,but some pearls are other colors
too, like yellow or pink orshimmery black. Pearls are
produced by mollusks, likeoysters and clams.
Mike McCann (21:58):
So we can talk about how oysters form their
shells first, right? So allmollusks, for the most part, are
taking minerals like calciumfrom the water, mixing them with
protein, and building their ownshells. And then their body sort
of grows and the shell growsaround them. And so that shell
typically has multiple layers.There's a sort of harder layer
(22:21):
on the outside and a smootherlayer on the inside. It's called
nacre, N A, C, R, E, or it'skind of a mother of pearl, is
another way to describe it. Itlooks shiny and pearlescent.
Jane (22:32):
And it's really smooth when you touch it.
Mike McCann (22:34):
Any mollusk that makes a shell can make this
nacre or mother of pearl layer,and so even oysters that you see
here, like the Crassostreavirginica of New York City, has
that nacre layer. But only somespecies of bivalves, and
unfortunately, this species,doesn't make the really round
and beautiful pearls. There'sonly a few species that are, you
(22:57):
know, often cultured, whichmeans humans really get
involved. Sometimes they'll evenplant a little seed to start the
process. So what's happening is,anytime there's an irritant, a
grain of sand, an infection, theanimal is basically
encapsulating or growing a layerof nacre around that object. So
(23:18):
if you were to find a pearl inan oyster, it would be probably
really weird-shaped andirregular. It wouldn't look like
a perfect sphere. Most of thosecome from species in places like
Australia and the Pacific, andthey're completely different
species, and they are culturedpearls.
Jane (23:35):
Basically anytime you see a pearl, you can think of it as
something that really annoyedthat animal, that what they made
was something to put aroundsomething that was annoying.
Mike McCann (23:45):
That's a great way to look at it. Absolutely. It's
a way to get rid of that pest,but it stays with you forever.
Jane (23:51):
Yes, much like our siblings, sometimes.
One of the coolest things aboutthe Billion Oyster Project is
how many young people areinvolved in it. There's a high
school on Governor's Island, andthe students there are deeply
involved with this project.
Mike McCann (24:07):
We really believe that restoration is not just the
job of adults, and we think thatyoung people and kids and
students are the next--they'rethe leaders of what the harbor
is going to look like in thefuture. So what a lot of what we
do is work with students andyoung people and give them
opportunities to--high schoolersat the New York Harbor School
(24:29):
work with us to drive boats andlearn how to operate boats
safely. They learn how to scubadive and monitor oyster reefs.
They learn how to weld andfabricate some of the structures
that get used in restoration.These are real hands-on learning
opportunities for kids, foryoung people, because they're
the ones who are going to betaking care of New York Harbor
(24:49):
in the future.
Jane (24:49):
The day we were visiting was actually a holiday, so none
of the kids were at school, butnormally they'd be doing all
kinds of work helping to restoreNew York Harbor and racing to
accomplish the goal of getting abillion oysters restored into
New York Harbor. I wish I couldhave done that kind of project
when I was in school. Maybe youhave some projects near you that
(25:10):
you could get involved with.Maybe not as big as the Billion
Oyster Project, but there arelots of science research
centers, museums and animal carefacilities or universities that
encourage citizen science andhelp young people get involved.
Ask your adults to help you findone if you're feeling inspired.
Back on Governor's Island, itwas getting really, really
(25:33):
rainy, and the last ferry backto the city was about to depart,
so we had to go! [FERRY HONKING]That's it for this episode.
Thanks to Mike McCann forteaching us about oysters and
sharing the work the BillionOyster Project is doing to
restore oysters and oysterhabitat in New York Harbor. As
always, if you have aquestion--about anything--have
(25:56):
an adult record you asking it byusing a smartphone. You can use
an app like voice memos, andthen have your adult email the
file toquestions@butwhykids.org. Our
show is produced by MelodyBodette, Sarah Baik and me, Jane
Lindholm, at Vermont Public anddistributed by PRX. Our video
producer is Joey Palumbo, andour theme music is by Luke
(26:17):
Reynolds. If you like our show,please have your adults help you
give us a thumbs up or a reviewon whatever podcast platform you
use to listen to us; it helpsother kids and families find us.
We will be back in two weekswith an all new episode. Until
then, stay curious!
This is But Why, A Podcast for Curious Kids, from Vermont
Public. I'm Jane Lindholm. Onthis show, we take questions
from curious kids all over theworld, and we go out and find
answers. This fall, on anexceptionally rainy afternoon,
the But Why team drove over toNew York City to visit a place
(00:40):
called Governor's Island. We hadto take a ferry to get there. We
went all the way to Governor'sIsland in the rain because we
wanted to learn about a veryspecific project and a very
specific animal. See if you canguess what it is! These animals
live in salt water. They'repretty small. Most species could
(01:03):
fit in the palm of your hand.When they're an adult, they
filter as much as 50 gallons ofwater per day per animal,
straining out pollutants andcleaning the environment around
them. They have no brains and noeyes, but they do have a heart.
And they're famous for makingpearls. That last fact might
(01:24):
have given it away. We'relearning about oysters today.
When you think about New YorkCity, oysters probably aren't
the first thing that springs tomind. But over a hundred years
ago, New York was known as theoyster capital of the world. You
could buy oysters from carts allacross the city, and oyster
(01:44):
shells were used in buildingconstruction. The oysters
themselves helped keep New YorkHarbor clean. Over time, though,
the oyster population declined,a result of over harvesting and
water pollution. And when NewYork Harbor lost its oyster
reefs, it also lost a lot ofbiodiversity--the wide variety
(02:05):
of plant and animal species thatmake a healthy ecosystem--and
that underwater environmentbecame more bare, less full of
crags and reefs and differentkinds of textures, which made it
less resilient and less able toabsorb floods and erosion.
But a group of young people,scientists and teachers have
(02:26):
been working for the last decadeto restore oysters to the harbor
in the hopes of reversing someof those negative consequences.
The project is called theBillion Oyster Project, and it's
headquartered on Governor'sIsland, which is why we were
there. When we got off theferry, we weren't sure exactly
where we were supposed to go,but then we saw a tall man drive
(02:49):
up in a golf cart and wave atus.
Okay, tell me who you are.
Mike McCann (02:52):
My name is Mike McCann. I'm Director of Science
and Research at the BillionOyster Project.
Jane (02:56):
We piled into Mike's golf cart, and he drove us to the
other side of the island, wherethere was a giant pile of empty
shells.
Describe these shells, becauseI'm looking at them and some of
these shells are really big.Some of these shells are really
small. Some of them are kind ofpurpley. This one is huge
compared to the other one. Sowhat are all these shells?
Mike McCann (03:17):
So 99% of the shells here are from oysters. So
we should back up and say,what's an oyster, right? An
oyster is an animal. It's amollusk.
Jane (03:25):
What's a mollusk?
Mike McCann (03:27):
An animal that has a shell, that makes its own
shell. Among the mollusks youprobably know: snails and slugs,
but octopus and abalone? Allthese things are mollusks. And
there's a branch of the molluskcalled the bivalves, and that's
where oysters live. So that'smussels and scallops and clams
(03:49):
and oysters. So they have bi,valve--two. That's what that
root bi means, and valve likethese two shells, which you can
maybe hear me clicking together.
Jane (03:58):
What kind of oyster shells are you holding?
Mike McCann (04:00):
So from the Gulf all the way up to Maine, up into
Nova Scotia, we have one singlespecies of oyster. Scientists
call it Crassostrea virginica,the common name, Atlantic
oyster, or Eastern oyster. Somost of this pile is of the
Eastern oyster.
Benjamin (04:20):
Hi, but why? My name is Benjamin. I am eight years
old, and I from Long Beach,California, and I want to know,
how do oysters make theirshells?
Mike McCann (04:33):
Yeah. So oysters are really special. Like all
these bivalves, they producetheir own shells. So you might
be familiar with a hermit crab,but a hermit crab doesn't make
its own shell. It actuallystole--it's a crab that stole it
from from a snail. So oystershave this very special tissue
called their mantle. And it'ssort of a very thin tissue
(04:56):
that's at the edge of theirbody. And they can take minerals
that are in the water, primarilycalcium, which is, you know, in
our teeth and in our bones. Sothey're taking calcium,
extracting it from the water,which there's plenty of calcium
in sea water, and they mix itwith protein. And then they can
secrete--layer by layer, thatmantle tissue can sort of build
(05:18):
more and more layers of shell.So as their body's growing,
their shell can grow around it,
Jane (05:24):
And does their shell grow for their entire life?
Mike McCann (05:26):
Yeah, that's right, they have a shell when they're a
baby, swimming free, swimming inthe water for those two to three
weeks, and then that shell iswith them for life. So unlike a
crab, who you may know that acrab can molt its exoskeleton,
where they basically climboutside of their hard shell. An
oyster never does that. It nevermolts. It never sheds that
(05:48):
shell. It has it for life.
Bennett (05:50):
My name is Bennett. I'm seven years old, and I live in
Grafton, Massachusetts. How longcan oysters live?
Mike McCann (05:57):
In New York City, many of our oysters, we've
restored reefs, and they mightbe seven or eight years old on
those reefs. Occasionally 10,12. I think we've heard from
other harbors, other estuaries,20 years old.
Jane (06:11):
20 years old. So you can have an oyster that's 20 years
old.
Mike McCann (06:14):
Yes.
Jane (06:14):
Old enough to go to college.
Mike McCann (06:15):
That's right.
Jane (06:16):
So if I look at one of these shells here, I can see
kind of rings on the shells.Does that tell me anything about
how old the oyster is?
Mike McCann (06:27):
Not precisely. You can get a general feel when you
see those sort of ridges andbreaks that there was probably a
period of rapid growth. But it'shard to infer. Like it's not as
precise as a tree ring, ifyou're familiar, so you can sort
of tell when summers and wintersare if you slice a tree trunk in
cross section. An oyster shell,it's a little bit less precise.
Jane (06:50):
I was trying to concentrate on Mike's answers
about what oysters are and howlong they live, but the giant
pile of shells in front of mewas really distracting. It was
just so big. If I had climbed upon it, I bet I could have seen
all of Governor's Island.
Mike McCann (07:08):
These are some good ones.
Jane (07:09):
Okay. How many shell pieces do you think there are? A
billion?
Mike McCann (07:15):
Oh, boy, that's a tough question. We have
collected 3 million pounds ofoyster shells from New York City
restaurants since our program'sbeen around. And you can imagine
each pound probably has a fewhundred or a hundred, so we
could do some math, 3 billion.
Jane (07:36):
Yeah, well over a billion.
Mike McCann (07:37):
Yeah.
Jane (07:38):
But wait, it's called the Billion Oyster Project, not the
3 Billion Oyster SHELL Project.So what's going on with all
these shells, and where do thebillion oysters come in? Stay
tuned.
BREAK (07:49):
BREAK
Jane (07:51):
This is But Why. I'm Jane Lindholm, and today we're
learning about oysters fromBillion Oyster Project's Mike
McCann on Governor's Island inNew York City. When we visited,
Mike had driven us across theisland from the ferry dock in
his golf cart to gaze inamazement at a pile of about 3
billion oyster shells. Theseshells, which also included some
(08:12):
clam and scallop and othermollusk shells, come from
restaurants all over New YorkCity. After people are done
eating their shellfish dinners,the restaurants give the shells
to Mike and his team, and theshells wind up on that pile.
Mike McCann (08:26):
This is sort of the raw materials, the building
blocks, for an restored oysterreef, or created oyster reef,
where humans get involved. Sowe've got tens of thousands of
pounds of oyster shell. It'sbeen collected from restaurants
all over New York City.
Jane (08:42):
Those are all oyster shells. I'm on a pile. I could
climb up this, and I would be,you know, queen of the mountain
if I climbed it.
Mike McCann (08:51):
And so these are going to spend about a year
outside curing. So there'sprobably, you know, little
specks of oyster tissue andother things on it. So we leave
them out here, expose theelements, so they get really
nice and clean. Then we cleanthem up, we crush them up, and
we combine them with ecoconcrete, and we build what are
called reef balls.
Jane (09:11):
It turned out those reef balls were actually right behind
us, so we turned around andwalked over to them.
Mike McCann (09:18):
So they look like sort of concrete domes with
holes maybe the size ofvolleyballs in it, and so that's
made of oyster shell, ecoconcrete, which is special blend
of concrete that oysters andother marine life really likes.
And this will be the sort ofbase of the reef.
Jane (09:39):
If you were to look at one of these, it looks kind of like
a very, very large plant pot,but the way they're stored here,
upside down. And it's got holesin it. So it's a little bit like
maybe if you use a colander toclean your raspberries or to
drain your pasta, it's kind oflike a colander for a giant.
Mike McCann (09:58):
And it weighs about 500 pounds, so definitely a
giant-size colander.
Jane (10:03):
Okay, so this is made up of eco concrete and oyster
shells?
Mike McCann (10:08):
And that's not enough to get a reef right. We
could put these in the harbor,and, you know, some fish would
be interested in maybe startbuilding a home around it, but
we need to introduce livingoysters. So also on Governor's
Island, we have what we call ourremote setting facility. And
these are giant shippingcontainers, big steel cubes that
(10:30):
we've retrofitted to hold thereef balls. And then we
introduce baby oysters. We canbuy them from professional
hatcheries, where we'll import70 million oysters at a time, 70
million, and we'll add those tothese shipping containers with
about 40 reef balls. And thenthose oysters, we're basically
(10:51):
going to recreate that processthat they'd be doing out there
in the harbor, where they'dspend a couple of days, find
their home on the reef balls.And then that can be the mobile
unit that we can then deploywherever we want, into New York
Harbor.
Jane (11:05):
Let's recap. The Billion Oyster Project takes billions of
shells from people who've beeneating shellfish for dinner. It
grinds them up and mixes themwith eco concrete, and then
turns those shells and theconcrete into these structures,
these reef balls, that they thencan drop into New York Harbor to
start forming the infrastructurefor oyster reefs. They add
(11:28):
millions of baby oysters to thereefs, and those tiny oysters
swim around and latch onto thereef balls and start building
their shells out of the calciumin the structures. As the
oysters get older and bigger,they stay latched onto the
reefs, and other animals beginusing those big, open structures
for safe habitat as well.
Cecily (11:49):
Hi, my name is Cecily. I'm 10 years old. I live in
Winnipeg, Manitoba, and myquestion is, what do oysters
eat?
Mike McCann (11:57):
Oysters eat algae, so they don't eat the big leafy
green seaweed kind of algae thatyou might be familiar with. But
in our harbor and in mostharbors, there's lots and lots
of microscopic algae calledphytoplankton. So these are
single celled algae that arereally abundant in huge numbers,
(12:19):
and the oysters filter thosemicro algae out of the water.
Jane (12:24):
They eat algae, and that helps filter the water. But how
are they actually doing that?
Mike McCann (12:28):
Yeah, it's an amazing process. Inside their
body, between the two shells, isa special tissue called the
ctenidium, and it--
Jane (12:38):
Can you spell that?
Mike McCann (12:39):
C, t, e, n, i, d, i, u, m. It's hard to spell out
loud.
Jane (12:46):
I did not think it was gonna start with a C!
Mike McCann (12:48):
Yeah, it's a tricky word. It comes from a Greek word
for comb, and it looks like atiny little comb. There's all
these sort of branches like youwould for the comb you use in
your hair, but they're coveredin cilia. And these are these
really tiny sort of hair-likecells, and those cilia just are
constantly beating, pulling thewater in. And this organ is
(13:10):
amazing, because the oyster canactually choose the particles
that it wants to eat and choosethe particles that says, "Nah,
that's not food. I don't want toeat that." And so on this
cone-like structure, there's allthese sort of conveyor belts,
and they can actually moveindividual microscopic algae
cell and move it to their mouth.And then, if there's, you know,
(13:31):
say, a piece of plastic, theymight say, "Ugh, let me get rid
of that." And they they bind itup with some mucus, and it comes
out as pseudo feces.
Jane (13:40):
Pseudo means fake. Feces means poop. So it's fake poop?
Mike McCann (13:44):
It never went through their body, but it kind
of looks and feels a lot likepoop.
Jane (13:50):
So if they're filtering bad stuff out and then putting
it back into the water, how isthat cleaning the harbor?
Mike McCann (13:57):
Right. So there's two ways that they can either
bind up or transform pollutants.So in that process of creating
pseudo feces, what they're doingis sort of taking it from the
water and depositing it andburying it into the sediment. So
it stays there, in many cases,and that's a good thing. But for
some of the pollutants, they canactually get rid of it entirely.
(14:20):
So in many estuaries, too muchnitrogen is one of the biggest
pollutants. 70% of the air webreathe is nitrogen. But too
much nitrogen in the water isactually a really bad thing. It
can cause algae blooms and allthese other problems in an
estuary. But the microbialcommunity that lives in and
around all those nooks andcrannies on the oyster reef
(14:42):
actually take that nitrogenthat's dissolved in the water
and convert it into nitrogengas, which then goes into the
atmosphere, where it's perfectlyfine for nitrogen gas to be. So
they're transforming andremoving nitrogen, one of the
biggest estuarine pollutants. Soan individual oyster can filter
tens of gallons, maybe up to 50gallons of water a day. That's
(15:03):
just one big, full grown oystercan really just move a lot of
water through its body and cleanit up.
Jane (15:10):
So what would a billion oysters do?
Mike McCann (15:12):
A billion oysters could filter, you know, a good
chunk of New York Harbor in afew days.
Jane (15:17):
That's pretty awesome. And you plan, or hope, to be able to
put a billion oysters into NewYork Harbor by...
Mike McCann (15:24):
2030.
Jane (15:25):
2030. Whoa. Okay, so you've got five years.
Mike McCann (15:28):
We're feeling optimistic.
Jane (15:30):
How many are you doing a year?
Mike McCann (15:31):
So, so far, we have returned 150 million oysters. So
we're currently doing about 25million a year. But in the next
year, our facility is going toexpand to do about 100 million a
year.
Jane (15:49):
Good, because you're gonna have to get speedier.
Mike McCann (15:49):
Gotta get moving. Yeah.
Aurora (15:50):
My name is Aurora. I'm five years old. I'm from
Brownsville, Texas. Why dooyster live in the ocean, but
not in the lake?
Mike McCann (15:59):
Oysters live in oceans because that's where
their mom and dads lived. Sothat's where most mollusk
species originated. So if you goback tens of thousands, hundreds
of thousands of years ago, whenmollusks originated, it was in
the oceans. And we know somemollusks, like snails and slugs,
(16:21):
have made it onto land. Somehave made it into freshwater
ponds, but the majority ofmollusks live in the ocean, and
it's a really tricky thing tolive both in the ocean and in
the fresh water, because all ofyour cells in your body need to
be able to osmoregulate, whichis basically balance salt and
(16:42):
water. And so you could really,for most organisms, only
specialize in one place, becausethe way your cells are trying to
balance, they're saying, "Hey, Ineed to get rid of excess salt."
Or "I need to get rid of excesswater." Most species have
adapted to just one of thoseenvironments, and not both.
There are a few exceptions, youknow, some fish species can span
fresh water and salt water, butit's a really hard task to do.
Caden (17:05):
My name is Caden. I'm four years old, and I live in
Rockland, Massachusetts. Wheredo oysters go in the winter?
Mike McCann (17:16):
So oysters, except for when they're a baby, can't
move, so they are stayingcemented in place on that reef
that they chose when they werejust two or three weeks old. So
what that means in a place likeNew York City, where it gets
really cold in the winter, thewater goes down to 33 degrees
Fahrenheit, that means they'restaying in place and they are
(17:40):
basically slowing theirmetabolic rate, and they're
living off all the food they ateall summer and all of those
reserve energy stores so anoyster can survive. And you
know, ice cold water.
Jane (17:52):
For 20 years!
Mike McCann (17:53):
For, well, you know, one winter at a time, for
20 years, yes.
Bennett (17:58):
My name is Bennett. I'm seven years old, and I live in
Grafton, Massachusetts. Myquestion is, what animals eat
oysters?
Mike McCann (18:07):
So oysters are food for other animals, and that's a
pretty natural and normal thing.So there are crabs that'll eat
oysters, like blue crabs and mudcrabs. There are fish, like the
oyster toadfish, it's gotspecial crunching teeth that can
break through shell. There'ssnails...
Jane (18:26):
Can you just pause on the oyster toadfish? Because first
of all, it has a fantastic name,but also it is a weird-looking
fish.
Mike McCann (18:33):
It looks kind of grumpy. It sounds like a toad.
That's how they communicate witheach other, and it loves to live
on oyster reefs. It's one of thereef residents. It sort of makes
their home on these reefs. Morepredators, oyster predators: so
we said crabs, we said fish.Also snails, like the oyster
(18:54):
drill, which is a snail that'ssmaller than a quarter, but it's
got a special mouth part thatcan drill holes into oysters,
and then they slurp out theinsides.
Jane (19:04):
So even though it's a fellow bivalve, it isn't like,
"Ah, you're cool."
Mike McCann (19:08):
There's no loyalties from the oyster drill.
And then sponges. There's asponge called a boring sponge,
boring not because it'suninteresting, but boring
because it bores holes into theoyster shell. So if we look
through that pile, we couldprobably find some oyster shells
that have had some boringsponge, looks like Swiss cheese.
Jane (19:27):
Oh, I think I saw one of those. And then, of course,
humans eat oysters.
Mike McCann (19:31):
Yeah, that's right. Oysters are, I think, famous
because of the fact that they'rereally delicious, and many
people love to eat them. Andthat's the source of these
oysters shells that we have hereat the shell pile. These all
came from New York Cityrestaurants where diners enjoyed
a dozen oysters on a night outon the town, and then they end
up here to be restored back toNew York Harbor. New York City
(19:53):
was, you know, once the oystercapital of the world in terms of
how many oysters were grown andproduced and harvested here and
shipped. Across the UnitedStates, over to Europe. Most
oysters at one point in timewere coming from these waters in
the 1800s but it's been 100years since we've had that.
We're not trying to restore apopulation of oysters in New
York City to eat anytime soon,our water is still much too
(20:15):
dirty for that.
Jane (20:17):
So that's one thing that you should be aware of when
you're thinking about eatingoysters, is that they are
incredible filterers. So youwant to make sure you're eating
oysters from clean water, notplucking one out of polluted
water.
Mike McCann (20:28):
Yeah, that's right. Oysters really reflect the water
that they're in. So you know,there are many places in New
York, not in New York City, ifyou go out in Long Island, where
the state has said these watersare clean and you can grow and
harvest and farm oysters here.
Lucy (20:43):
My name is Lucy. I'm six years old. I live in Guelph,
Ontario. Why is it safe to eatoysters without cooking them?
Mike McCann (20:55):
Yeah, so it's only safe to eat oysters if they've
come from clean water. And anyoyster you see in a store, in a
grocery store, a fish market, arestaurant, has come from waters
that have been designated safefor harvest, so oysters that
have been harvested from cleanwater and have been kept cold
(21:15):
are going to be safe to eat.
Jane (21:17):
So you should always check with your adult and maybe check
where you're buying the oystersfrom.
And don't harvest them from NewYork City.
Also, because we want theoysters to stay here, because
they're doing important work.
Mike McCann (21:28):
That's right.
Sarah (21:29):
My name is Sarah. I'm from Portland, Oregon, and I'm
eight years old. How do oystersmake pearls?
Jane (21:36):
Do you know what a pearl is? You might have seen pearls
on someone's earrings or anecklace. When you see them on a
piece of jewelry, pearls aretypically round and a lot of
them look milky white and shiny,but some pearls are other colors
too, like yellow or pink orshimmery black. Pearls are
produced by mollusks, likeoysters and clams.
Mike McCann (21:58):
So we can talk about how oysters form their
shells first, right? So allmollusks, for the most part, are
taking minerals like calciumfrom the water, mixing them with
protein, and building their ownshells. And then their body sort
of grows and the shell growsaround them. And so that shell
typically has multiple layers.There's a sort of harder layer
(22:21):
on the outside and a smootherlayer on the inside. It's called
nacre, N A, C, R, E, or it'skind of a mother of pearl, is
another way to describe it. Itlooks shiny and pearlescent.
Jane (22:32):
And it's really smooth when you touch it.
Mike McCann (22:34):
Any mollusk that makes a shell can make this
nacre or mother of pearl layer,and so even oysters that you see
here, like the Crassostreavirginica of New York City, has
that nacre layer. But only somespecies of bivalves, and
unfortunately, this species,doesn't make the really round
and beautiful pearls. There'sonly a few species that are, you
(22:57):
know, often cultured, whichmeans humans really get
involved. Sometimes they'll evenplant a little seed to start the
process. So what's happening is,anytime there's an irritant, a
grain of sand, an infection, theanimal is basically
encapsulating or growing a layerof nacre around that object. So
(23:18):
if you were to find a pearl inan oyster, it would be probably
really weird-shaped andirregular. It wouldn't look like
a perfect sphere. Most of thosecome from species in places like
Australia and the Pacific, andthey're completely different
species, and they are culturedpearls.
Jane (23:35):
Basically anytime you see a pearl, you can think of it as
something that really annoyedthat animal, that what they made
was something to put aroundsomething that was annoying.
Mike McCann (23:45):
That's a great way to look at it. Absolutely. It's
a way to get rid of that pest,but it stays with you forever.
Jane (23:51):
Yes, much like our siblings, sometimes.
One of the coolest things aboutthe Billion Oyster Project is
how many young people areinvolved in it. There's a high
school on Governor's Island, andthe students there are deeply
involved with this project.
Mike McCann (24:07):
We really believe that restoration is not just the
job of adults, and we think thatyoung people and kids and
students are the next--they'rethe leaders of what the harbor
is going to look like in thefuture. So what a lot of what we
do is work with students andyoung people and give them
opportunities to--high schoolersat the New York Harbor School
(24:29):
work with us to drive boats andlearn how to operate boats
safely. They learn how to scubadive and monitor oyster reefs.
They learn how to weld andfabricate some of the structures
that get used in restoration.These are real hands-on learning
opportunities for kids, foryoung people, because they're
the ones who are going to betaking care of New York Harbor
(24:49):
in the future.
Jane (24:49):
The day we were visiting was actually a holiday, so none
of the kids were at school, butnormally they'd be doing all
kinds of work helping to restoreNew York Harbor and racing to
accomplish the goal of getting abillion oysters restored into
New York Harbor. I wish I couldhave done that kind of project
when I was in school. Maybe youhave some projects near you that
(25:10):
you could get involved with.Maybe not as big as the Billion
Oyster Project, but there arelots of science research
centers, museums and animal carefacilities or universities that
encourage citizen science andhelp young people get involved.
Ask your adults to help you findone if you're feeling inspired.
Back on Governor's Island, itwas getting really, really
(25:33):
rainy, and the last ferry backto the city was about to depart,
so we had to go! [FERRY HONKING]That's it for this episode.
Thanks to Mike McCann forteaching us about oysters and
sharing the work the BillionOyster Project is doing to
restore oysters and oysterhabitat in New York Harbor. As
always, if you have aquestion--about anything--have
(25:56):
an adult record you asking it byusing a smartphone. You can use
an app like voice memos, andthen have your adult email the
file toquestions@butwhykids.org. Our
show is produced by MelodyBodette, Sarah Baik and me, Jane
Lindholm, at Vermont Public anddistributed by PRX. Our video
producer is Joey Palumbo, andour theme music is by Luke
(26:17):
Reynolds. If you like our show,please have your adults help you
give us a thumbs up or a reviewon whatever podcast platform you
use to listen to us; it helpsother kids and families find us.
We will be back in two weekswith an all new episode. Until
then, stay curious!
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