Claire Corlett

Fish Food, Fish Tanks, and More
Freshwater Fish with Dr. Katherine O’Reilly

Freshwater Fish with Dr. Katherine O’Reilly


hey everyone I’m still getting things
just set up so if you’re on a little early bear with me as I try and
make sure we’re all technologically sound here we’re getting Twitter updates when
you’re you know live-streaming it’s kind of a very surreal experience I’ll make
sure the fish are the main attraction here not my
random assortment of stuff that I’m taking with me too bad about the glare I really wanted you guys to see my beautiful artistic ability I am no
Sunday fish sketcher so this is my attempt at putting together a fish or
Skype a Scientist so we will I don’t want to you know
break the mold and go before things get started so for those of you who’ve
joined early we’ll be starting this off at 1 p.m. Eastern Time I was just you
know feeling very eager and wanted to get everything technically set up
and so if you’re here twiddle your thumbs for a few moments and then we
will jump it will dive right in to a an episode all about freshwater fish and
the places they call home Oh awesome we’ve got a classroom up Mrs.
Lindquist fifth grade gifted students class from Andover Elementary in Orlando
Florida thanks for joining me today I’m really excited to talk to you guys as
you guys are tuning in we are just you know just giving it a few minutes I
wanna you know stick play it by the books and start at 1:00 p.m. so I’m
so eager that I wanted to get started early I just love talking about fish
that much and I feel like I should have a
countdown timer in the background thank you it I do love this shirt I figured
you know I really when you get to be a fish scientist you start to accumulate
really silly looking shirts but this is one of my favorites so thanks guys what it we have a question already and
it is officially one o’clock so I can get into it I’ll give my whole spiel
afterwards but I want to definitely answer
Angelina’s question what which is what is the biggest freshwater fish and that
is an awesome question there are a couple different ways of looking at it
in terms of like a big fish being long versus a big fish weighing a lot and so
we are really you know there’s a lot of really cool fish that we’re going to
talk about today but some of the biggest fish there’s one called the Mekong
Catfish so if you’ve ever seen a catfish but the little whiskers on it if you’re
in North America you’ve seen kind of small catfish maybe they can get you
know kind of big the Mekong Catfish gets really big and this is a fish that lives
in southeastern Asia and it is really cool I will see if I can bring up
a picture at some point during my talk and I if I don’t get to pick up a
picture you guys should totally Google Mekong Catfish and you’ll just be like
how is that even a fish because it looks more like a small dog or actually not
even small dog probably like a really big dog so now that I you know already
started launching into the freshwater fish I just want to give you guys I want
to say thank you for joining me my name is Katie O’Reilly and I am leading
today’s Skype a Scientist live all about freshwater fish and the awesome cool
places they call home as you can see I’m not I’m kind of a weird scientist I’m
actually a PhD student so that means I’m still in the process of you know doing
research to become a doctor so you know a full-fledged scientist but I
really enjoy learning about the world around me
and being a student is a great time to get research ooh and someone did provide
a link to the Mekong catfish so thank you for that but so getting back to things I
am a PhD student at the University of Notre Dame which is a University in
Indiana in the United States I’m actually not in Indiana right now you
can see I not a scientist in a traditional lab setting this year I’m
doing a fellowship in Washington DC which is more science policy so if I get
a chance to talk or if you guys have questions about what being a scientist
working in the government is like and kind of you know seeing how you know
science can get applied in lots of different ways I’d be happy to talk
about that as well but so when I’m wearing my grad student hat back at the
University of Notre Dame I am a freshwater scientist I look at
freshwater ecosystems and particularly the fish that call these ecosystems home
I particularly look at the North American Great Lakes so if you ever heard the
term like HOMES there’s Lakes Huron, Ontario, Michigan, Erie and Superior and
this is one of the largest freshwater ecosystems on earth so it’s a really
cool place to do a lot of science and there’s some really awesome fish there
but first off like when I say ecosystem what exactly am I talking about what do
I mean by that in ecology which is the study of ecosystems it’s an ecosystem is
all of the living things all the plants and animals that are in a particular
area as well as all of the nonliving things that are around them so think of
things like Sun, the dirt, the weather, the atmosphere and the air and
together an ecosystem is all of those parts the living things the plants and
animals interacting with these nonliving things and what’s really cool about that
for me as a scientist who’s studying these ecosystem
I like to think of studying ecosystems as a bit of a puzzle in order to see the
big picture to see how everything works you have to look at all these little
different pieces put together and there’s so many different kinds of
ecosystems you know if you’re I do the freshwater stuff as I kind of said but
there you can study forests you can study grasslands you can study oceans
and there’s so we generally because there are so many of these things called
ecosystems we generally tend to group them into being either aquatic which is
water-based so that’s things like the ocean like freshwaters or terrestrial
which is land-based so it’s like kind of site a terrestrial ecosystem could be
something like a forest, a grassland and then within aquatic ecosystems so those
water-based ecosystems they can either be salty so you know you go to the ocean
you’re dealing with saltwater or they can be fresh so these are things like
rivers, lakes, ponds and what I find really cool and what drew me to doing
freshwater ecosystem science is that freshwater systems are all around us
you know you can have things everything from the mighty Mississippi River here
in North America which is this huge massive river to the large Great Lakes
which contain about 20% of the world’s fresh water which is really that just
blows my mind every time I think about it so you have these really big
ecosystems but what’s also cool and what’s also an ecosystem are really
small things so think of like a small creek maybe in your backyard or a pond
there’s even ecosystems within a you know plants so some plants can contain
like they can hold a little bit of water and then within that water in a single
plant you can have an entire ecosystem so plants animals just develop within a
single plant to me that’s so cool thinking about we can study things every
from massive oceans, the Great Lakes, all the
way down to these very small, little places and they all have similar similar
characteristics at certain levels so that’s really cool to me as I
said I study the Great Lakes of North America which is just a really if you’ve
never seen the Great Lakes it’s hard to believe like how massive they are when
you think of the word lake you tend that you know you kind of think
okay you know a small body of water I can maybe see across across the surface
but the Great Lakes are really more like freshwater oceans so they’re not salty
but you can’t look across and when you look across you just keep seeing water
they have rolling waves they have currents they’re really deep and so for
me it’s really cool you know looking at these freshwater ecosystems on a big
scale and seeing how the fish within these ecosystems live and live in and
contribute to the rest of it they play a part in their ecosystem so specifically
I’ve given you just my whole ecosystems are really cool you know this is
the setting for which we have these really cool characters called fish and
so what it may sound silly but like what is a fish
exactly and that might seem like an easy question to answer but it’s actually
pretty difficult for scientists to define what makes a fish a fish because
there’s just so much diversity in the shapes and sizes and just all the
general characteristics of fish because I’m not in my lab and I’m in Washington
DC right now I can’t show you real fish so I brought in a couple of my stuffed
yeah a stuffed animal example friends and just showing you know this is
obviously not super scientific but there is a whole diversity of freshwater
shapes and sizes anything from like a salmon which has kind of your
traditional fish body shape to more primitive fish such as a sturgeon which
if you like primitive fish you should totally check out an earlier Skype a
Scientist’s live session with Dr. Solomon David who really likes to talk about
some really weird-looking fish if you’re interested in that diversity so but
getting back to the question of what makes a fish a fish
they’re are even though there’s a lot of diversity and there’s a lot of
variation in the shapes and sizes of these animals they in general
that will be my disclaimer the in general are animals with they’re animals
called vertebrates so they’re animals with a backbone, they live in water, they
fish breathe primarily using their gills so not lungs like we do as mammals and
they also so again wait so we’ve said they have a backbone, they live in water,
they breathe using their gills, they also are what we call cold blooded so they
can’t maintain their internal temperature as well and they also
another thing is they have scales so we have a few general guidelines of what we
consider a fish you’ve probably got an image in your head of you know what
what’s a fishy thing is it like a goldfish in a tank but as
I kind of already you know given away the answer there’s within that broad
category there are so many exceptions to this these guidelines for example as I
alluded to a little bit earlier with these primitive fish the ones that have
kind of really awesome cool body shapes some of these primitive fish like lungfishes and gars actually can you know breathe
air using structures that you know are more similar to lungs than gills so
you know that’s off you know not all fish just rely on their gills there’s a fish called a mudskipper which
can live outside the water can actually use its its pectoral fins which are kind
of the fins at the front of the fish I could actually point out on my
whiteboard if the glare isn’t too bad so it can use pectoral which are these
fins as well as sometimes they can use these structures to you know
help them walk across land and live in muddy environments so you know not all
fish have to live in water all the time another expectation and you know
there’s even some fish and so I’m veering out of the freshwater sphere but
there’s some fish like tuna that can actually regulate their body temperature
so they’re not the traditional cold blooded fish that we think of so I think
that’s part of what really drew me to studying fish is that there’s so many
cool examples that we group into this study of fish that we call ichthyology
and there’s so much diversity and it’s fun figuring out you know why are fish
why are certain fish shaped or have you know different things that help them
survive in their environment their ecosystem and that is it’s studying the adaptations that allow them to be successful in
different environments and that’s just really cool to me as well and I don’t
know if I’ve said it too many times but if you’ve been paying attention
sometimes I use the word fish and other times I use the word fishes so fish
is one of those weird words in which you know it’s not plural all the time but
it’s a little more complicated than traditionally saying like you know
plural versus singular as scientists we use
fish to refer to multiple individuals of the same species so say I had 20 of
these little salmon stuffed animals I would say I had 20 fish if I had 20 of a
mix of these two animals I would say I have 20 fishes so the fish is referring
to a bunch of different you know different individuals of one species
whereas fishes is more generally used for a group of a bunch of different
species which is just kind of a weird fishing fun fact that’s not actually
more science but it’s something that a scientist we talk about and I always
like sharing that little blurb and I’m almost done with the end of my
spiel because I want to get to some of your great questions but where I kind of
you know got drawn in in addition to just thinking fish are these super cool
organisms that are so incredibly diverse and live in all different habitats you
can find fish from the very deepest parts of the ocean to you know one lake
on a mountain somewhere and that’s the only place it lives so fish are
remarkable in that you can find them almost anywhere you know anywhere
there’s water in some cases and they have the adaptations to help them live
in an environment but the other parts of the fish are awesome the other part of
what drove me to go to grad school and want to study freshwater ecology is the
freshwater ecosystems like the Great Lakes are just really they’re
really threatened because we rely on them so much like humans rely on them
for water, we rely on them for catching fish, we rely on them for creating our
energy in some cases and so because humans have such a close relationship
with the water that’s around them things like rivers and lakes that means they
also face a lot of threats that come from human interaction so this is
everything if you think of environmental threats
environmental issues they all are very front and center when it comes to
freshwater ecosystems so one of the biggest things but specifically
like is a threat to freshwater ecosystems throughout the world is what
we call habitat modification which is just a long word for saying we’re
changing how a river or a lake the structure of it so the best example of
that is when we create dams on rivers so we’re harnessing the power of the
river to create energy – you know regulate the flow to help provide water
but at the same time that can also mean that fish can’t get to places
they normally would so if you’re a salmon again you’re a salmon who needs
to swim upstream to get to the place where you were spawned or born to lay your
eggs and produce the next class of salmon if someone has a dam there
unfortunately you don’t you’re not like the mudskipper and you can’t go out of
the water so you can’t walk around and get beyond that dam and go upstream so
for these species that need to travel long distances that we call migratory
fish things like dams and other structures can really affect how much
they can get to places where they need to be they need to spawn or
reproduce so that’s one major threat that is happening around the world and
the Mekong Catfish that we talked about right at the beginning of the time it’s
one of those animals that’s threatened by the creation of dams on some of the
rivers in Southeast Asia so it’s that is a big issue that really affects a lot of
freshwater ecosystems around the world another one we could go on and on about
all of the different things that affect freshwater ecosystems and while there
are a lot of challenges that I think it gives us a lot of time to you know work
on solutions and we have a lot of amazing people and I’ve learned this working here
in Washington DC there’s a lot of amazing people working on solutions for
these challenges so there’s a lot that kind of a lot of things that
threaten freshwater ecosystems and that’s one of the things and that we are
going to work on to help protect the awesome, cool, amazing, crazy fish that
I love so much so that was just a lot of information to throw at you guys but
this is for you to ask me questions so I want to make sure I get to those so we
talked about what the biggest freshwater fish is which Angela is a great question
or Angelina it’s a great question I would say so the Mekong Catfish is one
of them another really big freshwater fish I don’t know if it’s considered the
biggest are some of the sturgeon species that live in North America those are
some pretty awesome animals they are just really they can grow really really
big which leads into another question that I wanted to get to which is is it
David asks is it true that keeping a fish in a small tank will keep its body
small to be honest I have not had too much experience you know raising
fish I know that’s kind of the myth is that you know you keep it in there and
it will constrain the growth because you know can only get so big but
if you know I don’t know I think that’s you have to have an appropriate size
tank for your fish because that’s you know not kind of fair to the fish’s
size but that is a great question I I’m gonna defer to you I think some of my
more aquarium minded friends I typically so most of my research is field based so
I don’t actually spend a lot of time with fish in tanks in the lab but
that is a great question that I’m hoping you know maybe someone else can chime in
and give us an answer to I’m used to just like finding my fishing and nature
and then the fun part about what I do a lot of time is I can you know catch
the fish we do our measurements and you know see
how long they are you know what kind of species we find and then we can release
them so that’s always really fun for me so it’s like oh you know
have a good life fish thanks for contributing to science but yeah great
question and if I see an update I will let you know David another one which is
from Mrs. Linguist class in Florida is are there any endangered freshwater fish
and that also is a phenomenal question because like I kind of mentioned at the
end of my spiel there are a lot of threats against freshwater and that is
leading to a lot of endangered freshwater species so it particularly I
can speak from the kind of North American side because that’s where I do
most my work and I’m most familiar with species there are a lot of endangered
species in particular regions so in the southeastern US there are a lot of
different fish species because there’s a lot of difference there’s a lot of
biodiversity and a lot of these species just already have very small ranges so a
range is kind of like you know I could say you know when I live in Washington
DC my range is the DC area it’s where I live it’s where I can go to the store I
can you know visit friends a fish’s range is kind of similar it’s like all the
places you can find the fish normally so in a lot of cases these species that are
in the southeast US have pretty small ranges like maybe it’s just one stream
or a couple streams in one part of the state and so with these fish because
they already have such a small area that they live in any threat so say someone
builds a dam or someone you know is cutting down some trees and that causes
a lot of sedimentation so a lot of soil going into the stream and messing you
know messing up the kind of status quo any small change can have
really big effects that can cause you know that species to disappear or go
extinct and so yeah so there are definitely endangered freshwater fish
especially a lot of these kind of rare like they’re normally rare
or have like small ranges in which they live so that is a great question and
they’re in addition to fish because you know even though I love fish and this is
all fish there are also other animals that live in freshwater
ecosystems that are pretty endangered again speaking from the North American
side of things freshwater mussels so you know when you go to the beach you think
of like clams maybe oysters things with a shell there
we also have freshwater mussels and a lot of really cool diverse species of
mussels in our streams, our rivers, our lakes and a lot of these have also
either you know they’re really threatened or they’re endangered because
being a mussel you know you don’t exactly have legs again to take you
anywhere you’re kind of stuck when you’re an adult when you’re
a larva you can kind of float on currents and move that way another really cool
fact sorry I’m thinking it because freshwater mussels are actually cool
because they need fish to complete their life cycles so get this when you have
when your freshwater mussel you know you’re hanging out at the bottom of the
stream you know doing your mussel things and if you want to reproduce you know
have babies you actually need to have a fish host so a fish will be you know
swimming on by and the mussels like how do I get this fish’s attention so the
mussels have evolved to have these little almost like lures so think of
like a fishing lure the mussel will put this out it attracts the fish sometimes
it looks like a small fish that they can come eat and then the mussel if when
the fish comes close it’s like oh hey awesome little snack the fish will
basically get a faceful mussel babies as weird as that may sound
but the mussel will send out some of its eggs to live on the fish’s gills and
that’s a key part of their life cycle again I think I’m gonna have to find a
video and share that with you guys because that is just it’s really cool to
see because it’s an example of how two species need each other so the
freshwater fish need these or the freshwater mussels need these freshwater
fish and in some cases like when we talked about dams the freshwater
if the freshwater fish can’t get to some place then the mussels don’t have the
host that they need to take their babies and help them complete their lifecycle
so again it goes back to that idea that ecology is all of these little pieces
kind of tied together and if you remove one part of an ecosystem you can have
effects that kind of like dominoes everything kind of collapses because you
took out a part that connects to a lot of different other pieces so yeah freshwater mussel I feel like we need a freshwater mussel Skype session
because those are also just really cool animals they have cool names like heel
splitter it’s wild they’re really cool animals as well okay next one
from Becca is is there any similarity between fish that live deep in fresh
water and fish that live deep deep in saltwater that is a phenomenal question
so freshwater and saltwater fish in general have I mean they can look very
similar you know body shape one of the biggest things between fresh and
saltwater fish that’s different is something you can’t actually see
really easily is the fact that their internal body chemistry is very
different and so what I mean by that is saltwater fish marine fish live in a
very salty environment obviously but because of that the salt water is always because
you’re living in salt water it’s always continuously bringing water out of your
body so these fish are always trying to like not become dehydrated if you’ve
ever tried to drink salt water which please don’t children this is not
a good decision to make salt water drinking salt water will
actually dehydrate you more so these fish have to have adaptations to deal
with that dehydration so what they do is their body is always trying to conserve
water and so they don’t pee very much and when they do pee it’s just a little a
little bit and that’s a way of them helping to regulate their body chemistry
freshwater fish on the other hand have kind of the opposite problem they’re
living in an environment where there’s actually less salt in the water that
surrounds them than the salt is just naturally in their body so water is
always coming into their body and this you know you might think okay well too
much water whatever but that can actually really throw off the fish’s
body chemistry and in that case one of the ways that they deal with trying to
keep their their salts their ions so we say regulated is by peeing all the time
and I mean it like all the time they are I think somewhere they can pee up to
about a third of their body weight every day and that to me it’s just a wild it’s
like wow and but it’s very dilute urine or pee and so this is just because
they’re trying to get rid of all of that water without losing too many of the
salts or ions that are inside their body so in general like those so a saltwater
fish and a freshwater fish deal with their environment again in a different
way and that is you know that’s kind of just the inside part of things but in
terms of deep specifically like so when we’re talking about really deep depths
fish have again adaptations that help them deal with
that really you know these really extreme environments so deep oceans
and deep lakes like really deep lakes so things like Lake Superior have a lot of
similarities you have high pressure so you’ve got all this water pushing down
on a fish think about if you go if you dive down to the bottom of a pool and
your ears start to hurt that’s kind of the pressure pushing down on you and
just kind of a fraction of what a fish would be feeling so they have to have
adaptations to deal with the pressure they also have to adapt to having not a
lot of light so in some cases depending on how clear your lake is you might be
able to get a little bit of light near the bottom but at like the deepest depths
of say Lake Superior or Lake Michigan you’re not going to get any light at the bottom either and in the deep sea if you’ve ever seen Finding Nemo when they go way
down to the bottom you know it’s dark down there and animals have to
create their own light so that they can you know they can see each other they
can find food and that’s a process we call bioluminescence so they’ve got
pressure, they’ve got this really dark environment where it’s you
know they have to figure out how do I find food how do I find you know my
friends and then they also have to deal you know these are it’s usually pretty
cold down there too you know you have the Sun warming up the top layers of
your lake or your ocean but it tends to generally get colder the further deep
down you go so you’ve got pressure, dark, cold and because you’ve got kind of
similar factors you’re gonna have kind of similar adaptations in terms of your
fish so what their bodies you know sometimes one way of dealing with it
dealing with these environments is you know really like your eyes are really
reduced so sometimes deepwater fish if you see pictures of them they look a bit
like aliens because they’ve got like either no eyes or their eyes are really
tiny and that’s just because they don’t need their eyes to see they’re not going
to see anything down there anyway and it’s you
know they’ve evolved other senses that help them better find their way around
so one of the things that you know fish can do other than like relying on its
eyesight is this thing called again we’re going back to the silly-looking
little fish I’ve got it’s this thing called a lateral line so in some case in
some fishes you can see this lateral line a lot easier but it’s basically a
sensory organ that fish use to feel kind of the pressure around them and
they can use that to sense prey since other fish without relying as
much on their eyesight so it’s you know the eyesight is one adaptation that
freshwater and saltwater fish may share when they are adapted for living at
really deep depths as well as sometimes their bodies just look really strange if
you’ve ever seen like a blob fish it doesn’t exactly look
great when you bring it up to the surface but that’s because you know it’s
body is adapted for the requirements of what you need to survive at the
bottom of the ocean and so sometimes that involves having a body structure
that’s really flexible you know and basically creating ways that your body
will restrict and withstand that enormous pressure that you have and
there’s a little bit of that in a freshwater side as much too I would say
there’s definitely more marine or saltwater fish that are adapted for life
in the deep just because you know we have deep oceans all around the world
there’s only probably a handful of lakes that get really deep and get kind of
that dark you know dark cold high-pressure environment that we’re
talking about I mean I’m thinking it’s things like Lake Superior which is part
of the North American Great Lakes where I do my work Lake Baikal which is in
Russia which is the deepest lake also fun fact
Lake Baikal in Russia has the only exclusively freshwater seal species so
that’s really cool it’s like you know we always see seals in marine
environments but there’s actually a lake where you can find seals but that’s
always just a really cool fact for me and then there’s some of the great lakes
in Africa so Africa also has a system that are referred to as the Great Lakes
some of those lakes are really deep and have fish that are adapted for more of
that deep environment but definitely more deep adapted fish in the oceans for
sure so Nick asks how do fish get into ponds that are isolated from other water
that you guys have just amazing questions I’m just this is really cool
but so one of that’s one of the challenges I think a lot of you know
some researchers are looking into is like you know say you have a small pond
that’s not connected to anything else there’s no stream that connects it
there’s no river you know how do fish move around in that case one of the ways
is actually humans so in a lot of places humans have introduced fish to different
ecosystems because they want to catch fish you know that’s one of
the ways people connect with fish is because they like going fishing they
like catching fish and in some cases that means that they bring the fish with
them which is not always a great thing it can be if a
fish isn’t native or not you know meant I would say it’s not native to an area
so it’s not originally from there by bringing in a fish that’s not from there
originally that can actually throw off the ecosystem because you’ve introduced
a piece that you know isn’t it hasn’t been in contact with the other plants
and animals there and sometimes it throws off the food webs of who eats who
and it’s a non-native species that’s been introduced somewhere where it’s not
originally from if it has a lot of negative effects
we call it an invasive species so one fish that I can think of that’s an
invasive species in the Great Lakes is actually from the oceans it’s a marine
fish called the sea lamprey and that was not brought intentionally so it was
brought or it came to the Great Lakes from the ocean but through some of the
canals that had been built to allow ships to move in and out of the Great
Lakes and connect to the ocean so that was kind of an inadvertent way that the
humans introduced the sea lamprey to the Great Lakes that they wouldn’t normally
have been able to get there but we made it easy enough that they could swim into
a new place like humans created that connection between the two ecosystems so in some cases maybe it’s a chance thing like there’s a
really big flood and a fish gets from it’s normal place and
it gets to a new pond and then you know if it got swept away and then that flood
is not there and then that pond is isolated sometimes things like that
happen there’s always a lot of weird chance events in nature which makes
studying nature so much fun because you never know what’s going to happen but so
there’s the natural ways like a flood you know maybe an animal has picked up a
fish and drop it off somewhere who knows it’s a bird those darn birds always
picking picking fish up and then dropping them places but it’s also a lot
of times because humans have moved fish there for one reason or another but
that’s a great question Nick thank you are there bioluminescent fish like there are
in the marine environment that actually is a great question I to my
knowledge I don’t know any off the top of
my head but I definitely would like to look that up because if anywhere I think
you know maybe some of those deep lakes that I talked about a little
bit earlier that might be where they exist
I really don’t know that’s a fantastic question and I am gonna be
looking that one up bioluminescent freshwater fish we got a team fish
we gotta get on it another one what types of fish do the big beluga fish eat
hmm so with beluga fish I know there’s a beluga caviar like beluga
sturgeon and there it’s weird but a lot of times fish have names that are like
based on other animals so sometimes you say like lionfish or I’m blanking on it
but it’s so it’s funny because like a lot of times you’re like talking about
fishing you’re like oh this is like another animal but I know the beluga
sturgeon and sturgeon are really cool and that they have like a and this is talking
again based on my knowledge of the North American sturgeon which are pretty
similar the sturgeon can actually like vacuum up so they hang out on the
bottom of like streams, lakes, rivers and they use their like suction mouths
to vacuum up you can kind of see he’s got his mouth on the bottom of his body
they use that mouth to suction up bugs and algae, plankton that are kind of
hanging out in the along the bottom of these rivers and lakes and so they they
kind of we call them benthic for hanging out at the bottom and you know feeding
on things that are also hanging out on the bottom but sturgeon are cool and
that they kind of have this vacuum mouth that sucks stuff up and
that’s always a really fun adaptation again it’s an adaptation to suit their
environment because the sturgeon live on on the bottom of the river they have
their mouths on the bottom so that it makes it easier to feed some fish that
live in the water column so that means like you know they’re
above the bottom of the river or lake and they’re hanging out in the middle of
the water they have their mouths either they can have their mouths in the front
so the salmon has the mouth in the front of its body while some fish even have their
mouth pointed up so that they can eat stuff that’s hanging out kind of above
them in the water and again the placement of the mouth is one of those
things that just helps it’s an adaptation so that they can be
successful they can survive in their environment so that’s really you know
fish are like all other animals their main thing in life is to survive and so
whatever are the ways that they can do that you know if it’s a mouth that helps
them feed a little easier it’s a body shape that helps them swim a little
faster these are things that give them a bit of an advantage and that means that
they can survive and then have babies that might share those those same
characteristics or attributes with them so that’s kind of where we think about
you know oh this fish is adapted to its environment it’s the strong and the
ones who are best adapted were surviving and reproducing or having babies let’s
see if I hit all of the questions thus far you guys have awesome questions
those are just really fun I did want to say hi to Mr. Chapman’s
fifth grade science class in Columbus Ohio thanks for joining me guys and you
are learning about different ecosystems and how food webs work and I have to say
I love food webs so within you know I said I study ecology which is the
study of all these different pieces a lot of the stuff I’m doing for my PhD
work is food web based and I’m looking at food webs in coastal wetlands which
wetlands are another type of aquatic ecosystem wetlands are kind of this
weird in between terrestrial aquatic ecosystem a wetland is like a marsh or a
swamp so it’s a place where you’ve got a lot of plants and it’s kind of like
muddy I like to joke again just jump in and get all muddy and like play around
stomping in the marsh all day but it’s also really important because there are areas
of water we’re a lot of really cool fish species live and so I’m looking at the
food webs in these wetlands which are really unique because you have parts
coming in from the terrestrial or the land as well as parts coming in from the
water or the aquatic ecosystem and so it’s really cool to see that all come
together and figure out you know is this fish eating stuff that’s come from the
land is it eating stuff that came from the water and like how much
do they rely on each each different food so yeah if you guys have any questions
about food webs I’d love to talk a little bit more about that as well Rosa that is a great question what is the deal with swim bladders why
do some fish have them and some don’t so swim ladders
are an organ that some fish species have that like a bladder contains you
know urine or pee a swim bladder contains air and this is an organ that
helps them regulate their buoyancy in the water column so we talked about the
different fish living in different parts of a river or lake and to adjust
like if you can go up and down you need some way to adjust how buoyant you are or
how much you float because obviously a fish doesn’t want to like you know hang
out right at the surface because again those darn birds hanging out you know
swooping in if you’re right at the surface you’re you know you could be a snack for someone but in some cases fish also don’t want to be right
at the bottom either because that’s not where they can find their food it’s not
where they can you know find other friends so the swim bladder helps
them adjust where in that water column they are in some cases not all fish and
like Rosa said not all fish have swim bladders so you probably like wonder how
do they regulate their buoyancy I’m actually thinking of one in particular
which again is not a freshwater species but if you bear with me I did my
graduate work in marine biology so I kind of feel like I’m you know dabbling
in both worlds of freshwater and marine biology but in marine ecosystems sharks
have these big livers actually like the liver takes up a lot of their body
cavity and the oil in fact in that liver helps them regulate their buoyancy
that way so in some cases of a fish doesn’t have a swim bladder it can also
have other organs that it can use to regulate that or if it just hangs out on
the bottom it may not need a swim bladder but that’s a great
question Rosa another question do all fish have gills oh that is a good
question there are some fish like I talked a little bit about earlier that
do not have gills or they have sorry do not need their gills all
the time so things like lungfish which are found in Africa in Australia and gar
which we have in in North America and other places they can you know they can
use their gills when they’re in the water but if the water has really low
oxygen which happens sometimes if water gets really warm or there’s a lot of
like chemical processes happening you can have low oxygen in the
water and in that case the gills won’t be much help because the gills function
by like bringing the water over or bringing water over the gills and taking
out the oxygen from that so if you have a fish that lives in really low oxygen
environments like gar and lungfish do they had to also evolve these lung like
structures so lungs like we have and you can see them actually go up to
the surface of the water, take a breath like they gulp air and then they go back
down kind of like you know a marine mammal like a dolphin or a whale does it
comes to the surface grabs a breath
and then comes back down so in some cases they you know they do have
the gills but they don’t always need to use them in some cases they’re you know
it’s a reduced function but that’s a great question hey we’ve got another
another question I saw a bunch of people on a beach pulling a shark back into the
water and someone said the shark probably would have died anyway because
its organs are too heavy does that only happen to sharks so
speaking as not a shark expert which you know I if you want to check out Dr.
David Shiffman on Twitter he’s at @WhySharksMatter he will answer all your
shark questions but i can talk a little bit about taking fish out of the water
because that is you know kind of an important issue obviously you wouldn’t
like it if someone grabbed you and put you in the water you probably you know
the fish it’s probably not the best day for them when they get taken out of the
water so one of the ways that scientists and anglers you know try and keep the
fish in the best quality of life is minimizing the time when we’re handling
them taking out of the water because it is tough on them they have you know
unless it’s like a cool gar or lungfish they may not be able to breathe because
they don’t have the water going over their gills and then they also a lot of
cases they have a mucus cover on their body which sounds really gross but it’s
really cool they have a mucus cover that helps them prevent drying out but if
you’re handling them outside the water some of that mucus can come out and that
can cause them to get sick and so we want to minimize that and so one of the
things there’s actually a researcher Dr. Steve Cook who is doing a lot i would
like this keep them wet campaign and that’s like you know we all love
catching fish like going fishing is really fun but just minimizing the time
like we keep the fish out of the water before we release it is really important
in terms of just keeping keeping the fish you know healthy and and handling
them in a humane way because you know it’s tough we don’t
we’re not normally in the water fish aren’t normally in the air and so
we gotta kind of you know be considerate of those but that is a great question I
had the shark thing I think would be really interesting to learn more about
so another question from Colin are there common freshwater fish in North America
that are also common far away like Europe, Asia, or Africa so the first thing
that comes to mind is actually going back to that kind of introduced and
non-native species there is a very common fish in North America that you
might not believe was actually not native here so if you’ve ever seen a
common carp or a goldfish we have those in a lot of rivers, lakes around North
America I know in the Great Lakes is specifically you know there can
be rivers and stuff around the Great Lakes region that have these really huge
goldfish and you know it’s because people have released them they are their
pets but there’s also common carp in North America have been around for a
while 1800’s etcetera you know they so they’ve
been here and common carp are originally from Europe, Eurasia and so this
is you know it’s an example of how species can get moved from one place to
another and then become very common within a particular habitat so
yeah so common carp not originally native to United
States North America and but now it’s a very common species that you may
see a lot but thanks Colin so Hank who is a great person to follow on Twitter I
believe it’s @spoonbill_hank and he is great for talking about you know
paddlefish which also a really awesome looking fish with a cool like flat
paddle you should you should totally check him out he asks what the biggest
threat faced by wetlands in the Great Lakes
and that is the biggest threat hmm that’s a tough one because there are a
lot of threats facing the wetlands that I study in the Great Lakes like I said
they’re kind of at this weird boundary between the water, the lake and the land
and so a lot of the things that we do on the land affect these wetlands
because they’re kind of like our buffer between the lake and so I’d say probably
the biggest challenge or biggest threat against the wetlands is just the fact
that we’ve gotten rid of most of our wetlands
they’ve been converted to other types of land use so wetlands have really
rich, really fertile soils so in a lot of cases they were drained and turned into
agricultural lands to grow you know the crops that feed us so that’s one case
but you know I believe there’s a stat but it’s something like 50% of all Great
Lakes its coastal wetlands that existed at one time are now gone because we used
it we’ve developed it into into some of the land that we live on and so that’s a
big challenge it’s just a lot of these fish species other animals which are
just cool as fish they all rely on these wetlands and now we’ve really reduced
the amount of habitat that there is for them and so that’s one of the big
things but there are a lot of groups doing restoration so I know in Western
Lake Erie they are doing a lot in terms of trying to bring back the coastal
wetlands because the wetlands are just they’re like the superheroes of
the ecosystem world they are great habitat for fish they help improve water
quality so they kind of act like a sponge and they take in all the
nutrients and runoff and kind of you know hold it and prevent it from getting
into a lake so they’re just these really awesome ecosystems that we
are we’re trying to get back and get back some of what we’ve lost
but thank you Hank that’s a great question how did fish make that mucus
cover and is the mucus cover of a freshwater fish different than a
saltwater fish one of the you know again that’s kind of one of those adaptations you know I’m really not sure that’s a great question I don’t know too much
about the exact physiology of how they create that mucus cover but yeah wow
that is actually that’s a great question I want to look that up and get
back to you because I I would like to know how they make the mucus cover too I
and the first thing that popped into my head is there’s actually a saltwater
fish called the parrotfish which can create like a mucus bubble so it’s not
just the mucus on its scales but it actually creates a mucus bubble around
itself which is weird because you think of it’s like you’ve created this giant
snot bubble but it’s a way of like keeping itself free of like parasites
while it rests at nighttime and that’s kind of you know what the mucus cover in
general does like on the scales not the big snot bubble is keeping a fish
protected from some of the stuff that’s around it you know it’s always in the
water there’s parasites there’s whatever and so the mucus cover serves as a
protective function but I would like to know how a mucus cover is made as well
and I will hopefully get you an answer
stay tuned but thank you Natasha that’s a great a really interesting question
that I want to learn more about we have another question that one time I had a
goldfish jump out of the tank and when I put it back in all its scales fell
off and then when it grew back the side turned white do you know why that happened
hmm Sarah that is a great question in a
lot of cases you know the one thing about scales that’s really nice and
scales is the fish is always growing its scales so you know even though it’s like
Sarah said it lost its scales when it jumped out it was able to regrow them
I’m not sure exactly why they grew back a different color that’s really in
testing but one of the cool things about scales that I think is is kind of I
actually didn’t know about it until I like was in which in college and that’s
probably like you know kind of a silly confession for the ichthyologist to know
but scales can be used to tell the age of a fish so there’s a couple of
different structures that fish have where we can use them to find out how
old they are because unfortunately you know every time I ask fish you know
their age they you know give me the cold shoulder there’s no response but instead
what we do is we look at scales we look at otoliths which are the ear bones in
fish and since these structures the scales, the otoliths are always growing
throughout a fish’s life we can actually count the rings that are in these
structures like tree rings almost you can count the rings and see how old they
are and it’s cool that you can do that with both the otolith which is in the
fish’s head as well well as the scales which because you can just take a scale
off and it regrows like Sarah’s fish did that’s not a lethal way of sampling
and figuring out how old a fish is because obviously with the otolith
really tough to get out when the fish is alive so that’s usually what we call a
lethal sample where we have to sacrifice the fish but we can also use scales in
that way to age them so while I don’t know exactly why the fish’s scales
grew back light that’s really interesting and it’s that would actually
be kind of a cool you’d have to like think about you know the
different processes that went into turning it white maybe the fish was so
stressed and that you know you got like gray hair but no it’s a silly kind of way of looking at but it would be interesting to do for me to do
a little bit of digging and see if I can find any any places where that’s
happened before so thanks Sarah so I think I have reached the end of
your questions and I want to be respectful of your time
thank you guys so much for for joining me if there’s a few other questions we can
hang out a few minutes more but I just want to thank you guys so much for
joining me today it’s been my pleasure talking to you thanks for letting me geek
out about fish and you know I’m happy I’m hopefully going to answer figure out
a couple of those questions and I will post things on my Twitter which is @drkatfish hopefully we can you know get you the link because I want to those
are some really great questions and I want to make sure I get to all of them
and figure out some answers for you guys so with that have a wonderful Friday
wherever you are and thanks again for joining me thanks for joining on Skype a
Scientist live

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