- I'm Professor Kory Evans.
I study fishes.
Let's answer some questions from the internet.
This is "Marine Biology Support."
[upbeat music]
@GabeSavage6 asked,
"Is 'Finding Nemo' an accurate representation
"of ocean life?"
Yes and no.
One thing that they did get right
is that clownfish do in fact live in anemones,
and they are in fact immune to the stings of the anemones.
One thing that is pretty different
is that clownfishes actually can change their sex.
So in the movie, Nemo's mom gets eaten,
and in real life,
after a female clownfish is eaten or dies,
the largest male will then become the female.
So Marlin in "Finding Nemo"
would've actually become a female clownfish
and laid his own clutch of eggs
within probably the next week or two.
So another thing that's different is Bruce the Shark.
So in the movie Bruce the Shark is a male shark,
but if you look close,
Bruce the Shark does not have claspers.
Claspers are the male intermittent organ the sharks have,
they're on the pelvic fins.
They're basically two very long penises.
Clear as day.
And Bruce doesn't have them.
So Bruce is technically, maybe a female shark.
@DoGsMoveSilent asked,
"Why is white sand different from brown?"
White sand is generally derived
from the shells of other animals.
Shells get broken down
either via wave action or via animal feeding.
And brown sand is different
in that it's typically the result
of rocks that have been eroded over time.
Most of the white sand comes from very unlikely source,
and that is parrotfishes.
They feed on coral skeletons,
and when they excrete it,
they excrete it as this nice white fine sand.
So much of the white sand that you see
is derived from parrotfish poop.
A single parrotfish
can produce 450 kilograms of sand per year.
So that's a lot of poop, that's a lot of sand.
@mayerwin asked, "How do schools of fish swim in harmony?"
So in order to answer that question,
we have to talk about the sensory systems of the fish.
So all fishes, for the most part,
have what we call a lateral line structure,
which is just a long line that runs from head to tail,
and it's covered with what we call mechanical receptors.
These are literal hair cells
that can sense changes in water pressure.
This is why if you ever try to catch a fish with your hand,
even if it's looking away from you,
it generally gets away from you.
And that's because when you put your hand in the water,
you push water towards these lateral line cells,
and the fish knows where you are without even looking.
Typically in a fish school,
one fish will generally respond
to the movements of the fish that's right next to it.
So as this fish moves,
it's gonna push water towards the lateral line of that fish.
And if you repeat that over a really large scale,
that's how you get
these really nice harmonious and synchronized movements
across fish schools.
Swimming in schools makes it easier to move through water.
Water is what we call highly viscous.
So when you have something in front of you
that's breaking up
kind of the flow and distribution of water,
makes it easier for the thing behind it to swim.
@muskoka_mike2 asked,
"Why are orcas attacking boats?"
The short answer is they don't want them there.
They're trying to move the boats out of the way,
and the boats generally disturb their marine environments.
Humans generally have a very long history
of messing with whales, especially from boats.
Humans basically wiped out
most of the whale populations in the Atlantic
via these whaling boats.
The unique thing about orcas
is that orcas kind of have culture like humans do.
They have the ability to transmit information
to subsequent generations
without having to pass it on through their genes.
Some orcas actually do have fashion.
There was a trend where one orca
started wearing a fish as a hat,
and later on the other orcas in the pods
also started wearing fish hats.
And then this fashion
actually jumped to other pods of orcas
also trying on the fish hat craze.
@reds_cp asked, "What is the fastest sea creature?
"No Google."
No Google needed.
The fastest sea creature in the ocean is the sailfish.
These fish can get up to 50 miles an hour.
Many of the fastest sea creatures
happen to be warm-blooded,
or what we call endothermic.
Tunas are famously warm-blooded.
These animals are also high-speed swimmers
at about 40 miles an hour for a tuna.
@MyshkinFool asked, "Serious question.
"Where do shells come from?
"Does marine life make them and then abandon them?"
All shells come from animals,
generally invertebrate animals
that basically lay these down as protection,
and things like this conch shell,
which is actually the remnant of a very large snail.
Marine invertebrates over the past 300 million years
have evolved the ability
to take in minerals from sea water and their food,
limestone or calcium carbonate,
and construct them into these very elaborate exoskeletons.
Sometimes you'll find shells
that have holes in the top
They're simply from a marine predator.
It's like boring snails.
Where they'll actually drill a hole
into the shell of this animal and consume it.
Some shells are really, really pretty,
and you might be tempted to pick them up.
One example here is the cone snail shell,
but the animal that lives in these is incredibly dangerous.
The cone snail is actually a venomous snail.
We don't have a antidote for their venom.
If they're disturbed,
they will shoot a harpoon full of venom
into the pocket of the person
who's likely put the shell in their pocket.
So even though they're beautiful,
some shells should stay at the beach.
@GeorgeM68340969 asked,
"The starfish has no brain.
"So how does it know it's hungry?"
The short answer to this question
is to assume the starfish is always hungry
because they most likely are.
They are voracious predators.
The starfish has no brain,
so it doesn't have a centralized decision-making center.
However, each arm is packed with sensory structures,
and each arm will basically taste the water,
and once enough kind of tentacles
start pointing towards where the food is,
the entire animal
will then kind of move its body in that direction.
Once a starfish lands on something that it wants to eat,
say, this clam for example,
it'll actually force the shell of that clam
open just a little bit,
and it'll insert its stomach into the shell of the clam.
So it'll eject the stomach out of its own body
into the shell of this clam
where it will then digest the clam inside its own shell
and then draw the stomach back inside of them
when they're done feeding.
@neongundam asked, "How can a mantis shrimp
"see more colors than I can?
"You're telling me
"there's a color out there called blurple that I can't see?
"Brellow? Gred?
"Man [beep] science and [beep] shrimp."
Yes, the mantis shrimp and many other aquatic animals
have the ability to see far more colors than we can
because they have more photoreceptors in their eyes.
So mantis shrimp can see well into the UV spectrum.
I'm not even sure
that this is the craziest thing about mantis shrimp.
Some mantis shrimp have the ability to punch so fast,
it looks like a flick when they punch,
that their actual punch and club
tears water molecules apart.
And when the water molecules rush in to fill that space
that's been created,
it causes them to boil at really, really high temperatures.
Inside of this little bubble of boiling water,
the temperatures can reach and exceed
the temperature of the surface of the sun.
@DynamicWebPaige asked,
"So freaking jealous of anglerfish sometimes.
"Why didn't I evolve
"with a built-in nighttime reading lamp?"
The short answer is
because you didn't evolve in the depths of the ocean
and you don't have to draw your food towards your mouth.
So in the anglerfish head,
there's a fin at the top
that's been transformed into a lure.
And in deep-sea angler fishes,
this lure is bioluminescent, so it lights up.
And they use it to attract prey.
What this anglerfish will do
is it'll sit there in the middle of the water column
with this light-up lure in front of its face,
and fish will come in thinking that it's food,
and they will then themselves become food.
@w_onderbot asked,
"What is the smartest animal in the sea?"
It's hard to compare intelligence,
but I would probably argue dolphins.
They have the ability to pass the mirror test,
which is being able to recognize themselves in the mirror.
Other examples include octopuses.
Some octopuses are able to solve maze problems
in order to find food.
Also, fun fact, many octopuses have the ability
to rapidly change their color to match their surroundings.
@JPBlough asked,
"How do octopuses change their color?"
Their skin actually has the ability
to see or perceive the color of the background
that they're sitting on,
and that information is somehow passed on
to the chromatophores that lives underneath the skin.
Each chromatophore holds one pigment.
There might be a blue pigment,
a red pigment, and a yellow pigment.
They can rapidly change the distribution
of these pigments in their skin.
It allows 'em to rapidly change color,
and they have fine-scale control
over each of these pigment cells.
@MrMckenzieSD5 asked,
"How do you tell a fish's age?"
So fishes generally have indeterminate growth.
However, there is a way to tell.
This is a 3D-printed fish skull.
There are a couple bones in the back of the skull here
that are called otoliths.
They're underneath the skull,
but if you were to pull them out,
you'd find these really nice coin-shaped bones
that have these concentric growth rings around them.
So fishes lay down these growth rings in their bone,
much like trees do.
So you can actually count the rings in fish bone
much like you would in a tree.
@xo_dani asked, "Fish fry at my grandma's today.
"Fish with bones and fish without bones.
"Yeah, this is how I classify my fish."
This is how I classify my fish too.
So it turns out
you can actually classify much of vertebrate diversity
into these really neat categories
of fishes with bones and fishes without bones.
All the vertebrates that have jaws
can be broken into two distinct categories.
So there are cartilaginous fish,
which are sharks, stingrays, and the rare chimaera.
And then there are bony fishes,
which include trouts, frogs, cats, dogs, and you and me.
Yes, even you and me.
Biologists typically classify humans and mammals in general
as a group of organisms
within the larger clade of bony fishes.
@CPFtrainer asked,
"Do all fish have similar numbers/types of fins,
"and what are these fins called?"
Some of the common fins you might see
are these pectoral fins off on the side.
Pectoral fins in general
are often used in hovering behaviors.
So you see these in fishes that live in coral reefs.
So things like wrasses and triggerfishes
will oftentimes flap their pectoral fins
to hover over a structure
to further investigate whatever is living in it.
The fins at the top are typically called dorsal fins.
The front dorsal fin is particularly interesting
because they oftentimes get adapted into venomous spines,
sometimes even fatal in the case of the stonefish.
In the case of this little Nile perch,
it looks like one continuous dorsal fin,
but there's basically a skin connection
between the front, spiny dorsal fin rays
and the back, kind of feathery dorsal fin rays.
This back fin is called the caudal fin,
and it's used to generate thrust.
If a fish is trying to get away,
it'll beat this tailfin to help it move quickly.
@Niv_Writes asked, "Does coral count as an animal?
"It's so alive and so pretty."
It is in fact an animal,
and it's also alive and very pretty.
They're closely related to jellyfish,
but instead of floating in the ocean,
they build these complex limestone skeletons.
So you can see these little holes
and pockmarks inside the coral skeleton,
and that's where the individual polyps live.
So in life, this coral would be very, very colorful.
However, this particular skeleton is bleached.
So when corals get stressed
because of higher temperatures in the ocean,
they'll expel the algae that they keep inside their tissues,
and they'll basically have no way to feed,
and they'll starve
over the course of the next several weeks.
Losing these reefs,
which can happen very, very quickly,
will have catastrophic effects
on tropical diversity worldwide.
So ways to prevent this include:
reducing global temperatures,
taking climate change seriously in general,
and in some very isolated cases,
pumping cold seawater back onto the corals.
@elizabeth_roush asked,
"How does the goblin shark even eat
"without its nose getting in the way?"
Goblin sharks have these very, very elongate rostra or noses
that they use to sense other animals in the water column.
In order to feed,
they actually have to protrude their mouth
out away from their nose
to catch prey and bring it back.
If you just try to bite something underwater,
you'll actually push it away from you.
So many animals have evolved the ability
to protrude their mouths
and generate suction to bring prey towards them.
Another one is the sling-jaw wrasse.
They have the ability to protrude their jaw
up to a third of their total body length
to bring in evasive prey, and then retract it.
@jameson_rich asked, "Never forget
"that there's a creature on this earth
"that was discovered and named by the people of science
"the vampire squid from hell."
So, yes, vampire squids are real.
They are a thing.
They were discovered in the late 1890s
in the Valdivia expedition.
If you dropped a net
thinking that there would be no life
at the bottom of the ocean
and you pulled up that vampire squid,
you would name it the vampire squid from hell too.
Contrary to their appearance,
which can be quite terrifying,
these animals have basically made a living
out of doing nothing.
They live in oxygen minimum zones in the ocean,
so they very rarely ever move,
and they feed primarily on leftover food
that basically floats down from the surface.
@Jacquel8277638 asked,
"OMG, when did whales learn to walk on land?"
Whales learned to walk on land about 35 million years ago.
So all whales, manatees, and seals
evolved from ancestors that once walked on land.
These whale ancestors gradually became more aquatic,
and as they got larger
and as they became more adapted to aquatic habitats,
they evolved a broader range
and a wider range of dietary strategies.
@stephanieelino asked,
"There's no way seahorses are real."
Seahorses are quite real.
Seahorses have been around for 13 million years,
and in that time,
they've actually evolved a broad variety of body shapes
typically associated with camouflage.
There are things like the leafy seadragon,
which looks like a piece of kelp.
Seahorses are terrible swimmers, some of the worst.
To get around that,
they've evolved these prehensile tails
that allow them
to basically wrap their tails around structures
so that they can stay put.
The seahorse is perhaps most famous
for the fact that the male seahorse gives birth.
The female will transfer her eggs into the brooding pouch
of the male seahorse,
and then when the eggs hatch,
the male seahorse will actually give birth
to the little seahorse babies.
@bybrandonwhite asked,
"What is the best defense mechanism in the sea?"
My favorite defense mechanism in the sea
actually happens to be electricity.
You see this in torpedo rays and stargazers oftentimes,
where if you grab them, you'll actually be shocked.
The way that they are able to shock you
is using these modified muscle cells
that have evolved to be able
to generate an electric current.
For some electric fishes,
for instance, the electric eel,
the current can be as strong as 600 volts.
The electric eel can drop a horse.
But perhaps the weirdest defense mechanism
that you'll see in the sea
actually comes from hagfish slime.
Hagfish slime feels weird.
It feels wet, slimy, but also fibrous.
So as you pull it apart,
it still has some consistency to it.
If a shark, for instance,
will come and take a bite out of a hagfish,
before the shark can even bite down,
the hagfish will secrete slime
and clog up the shark's mouth and gills,
allowing it to make an escape.
@MWSRXO asked, "What do fish breathe in, water or air?
"Wow, how do they make bubbles down there?"
So fish actually breathe oxygen.
They bring in the oxygen from the water,
and they extract it with their gills.
These gills are really sensitive.
They're often one or two cell layers thick.
They have to remain really thin to allow for gas exchange.
The internal structures here
that you can see in the gills are called gill rakers.
They'll swim through a school of plankton
with their mouths open,
and these rakers in the gills
will trap the plankton
while allowing water to pass through.
One way that fishes generate bubbles
is through their gas bladder.
So some fish, like, for instance, the Dojo loach,
actually has the ability to release gas out of its anus
to sink further down into the water.
@MJDookwah.
"It's crazy how sea creatures
"just know exactly where to go when they migrate."
Some marine animals
will follow the magnetic field of the Earth.
Big migrations include the migrations
that we see in humpback whales,
as they move from the tropics
where they give birth and where they breed
to temperate and colder feeding grounds
where they'll feed on plankton.
Other big migrations include salmon.
They grow up in freshwater,
they move out to the ocean,
and then they can return
to the stream that they were born in to reproduce.
And they accomplish this
by following the Earth's magnetic field
and also tracking the scent of the stream
that they were born in.
@TheHinduScience asked,
"What is the Diel Vertical Migration
"and its role in carbon sequestration?"
The Diel vertical migration
is the largest migration on the planet.
This occurs every night all around the world
where plankton will actually move up
from the depths of the oceans.
There's mixing of the carbon dioxide in the air
with the water right at the surface.
Plant plankton will basically extract
carbon dioxide from the ocean
and use this carbon to build their bodies.
Larger plankton will then come and eat these plant plankton,
and then fishes and other animals
will come eat the larger plankton as well,
and then sink back down to the depths,
taking that carbon with them.
So it actually ends up being very important
for the sequestration of carbon dioxide.
@C4_A_1 asked,
"Do you ever think about what lives in the Mariana trench
"and freak yourself out?"
Yes.
The Mariana Trench is the deepest point in the ocean.
36,000 feet deep.
It's deeper than Mount Everest is tall.
We have actually reached close to the bottom.
James Cameron and about six other ocean explorers
have taken submersibles down into the depths
of the Mariana Trench.
At that depth, the ocean reaches pressures
that would basically crush us instantly
if we ever went down there.
But many animals have evolved to actually live there.
In order to do so,
vertebrates have generally reduced their bony skeletons.
You probably wouldn't find a megalodon
at the depths of the Marianas Trench
because megalodons actually evolved
to live in shallow tropical waters like in The Bahamas.
But you might find like some weird clams.
@C22HONCHO asked,
"How do these bioluminescent waves work?
"Do people just throw glow sticks in there or what?"
These bioluminescent waves are widespread around the world.
You can find them in places like Puerto Rico.
You can also find them off the coast of the Pacific Ocean.
They're produced by plankton,
and whenever plankton are startled or disturbed,
they'll release bioluminescence to disorient predators.
So they'll have little openings in their exoskeletons
that allow for light to be produced.
@nekkohbk asked, "Y'all knew jellyfish are immortal?
"Like them bitches don't die...ever."
Turns out some jellyfish are in fact immortal.
The immortal jellyfish, so aptly named,
has the ability to revert back to its juvenile stage
if it's ever injured or starving.
It will then later produce
a genetically identical clone of itself
to further perpetuate itself.
Other animals in the ocean are famously long lived.
The Greenland shark is a great example.
These animals can reach 600 years.
Many of our large whales
can live for hundreds and hundreds of years.
There are still whales out there today
that have the old harpoons from harpoon ships
still embedded in them.
Some lobsters can get pretty close to being immortal.
Whenever a lobster grows,
it actually has to shed its shell.
They're very vulnerable during molting process
because their soft parts are basically exposed,
and many animals are really cued in
to find crustaceans that are molting.
So especially once they get older,
it gets harder to escape that molting shell.
So a lobster that's been alive for 150 years
might finally die by, at last,
being unable to escape that shell.
The estimates for lifespan are technically indefinite
because if nothing eats them,
they can just keep going.
@hannahexgirl.
"I need to know why evolution keeps making crabs."
So we don't know why things keep turning into crabs,
but things that are not crabs
keep turning into things that look like crabs.
An example of an animal
that has evolved into a crab is a hermit crab.
Hermit crabs are not true crabs.
If you're trying to picture what a hermit crab looked like
before it became a hermit crab,
it most likely looked quite a bit like a shrimp
or a very skinny lobster.
So over the course of tens of millions of years,
these hermit crab ancestors began to roll their tails up
and project them at weird angles,
and also enlarge their claws,
and eventually came to resemble
the crabs that we know today.
@I_Am_Winter asked,
"Fishes don't have eyelids, so do they ever sleep?"
The answer to that is yes.
During the sleeping process in fishes,
part of the brain shuts off,
but they're still able to breathe.
So you can still see their gill flaps moving.
They have reduced response to stimuli
so you can swim up
and basically touch a sleeping fish in many cases.
In the case of whales,
the patterns are very much the same.
Part of their brain
tells 'em to go up and take a breath of air,
and then they'll do that,
and then they'll come back down,
all while sleeping.
Sperm whales are really famous for this
because they sleep vertically in pods.
You can stumble upon a pod of sleeping sperm whales
that look like big, tall forests in the middle of the ocean.
So those are all the questions for today.
Thanks for watching "Marine Biology Support."