Hello this is Dr. Lyons and today
we're gonna be talking about the second
group of invertebrates that we're going
to cover in Chapter seven so as I was
saying before chapter seven is split up
into four parts in the last part we
talked about it's kind of some general
is about about invertebrates such as
what they are
in general we talked about the sponges
and then in this part we're going to
talk about three new groups that we
haven't discussed yet the the cnidarians
the the teen of four is in the mollusks
and what you're seeing in this picture
is a type of cnidarian this is what a
particular species of coral and the in
the indo-pacific looks like and and so
we've already seen this this
evolutionary tree before last time like
I said we talked about the sponges these
guys over here and what we're going to
be getting into today is these three
groups so that I Darien Stettin aphorism
in the mollusks and we're kinda slowly
working our way from the sponges all the
way up to the chordates that's what
would be out at the very end of chapter
7 so something that we're going to kind
of talk about is is what coral and
jellyfish have in common
so corals and jellyfish are both in this
group the phylum Cnidaria
and as a reminder when you see words
that have two consonants at the
beginning that don't seem to fit such as
the CN n typically the first letter is
silent so it's pronounced cnidarian so
just just cut out that C there and so
we're going to talk about what corals
and jellyfish which are both cnidarians
we're going to talk a little bit about
what they have in common so for instance
something that they both have in common
is radial symmetry so we discussed how
animals have either radial symmetry
bilateral symmetry or have no symmetries
sometimes called a regular symmetry so
radial symmetry that's one of those
those animals have kind of a circle
shaped think of like a typical jellyfish
it has kind of a circular shape to it
everything
originates from the center and works its
way out as opposed to like a human is
bilateral it has a left and a right side
as opposed to a sponge which doesn't
have any symmetry which is why we call
it a regular symmetry the cnidarians are
mostly marine there are some that are
found in freshwater but most of them are
found in the ocean and there's two
general body shapes that cnidarians can
have then you'll find all of them in one
is what's known as the medusa body form
and so that's what this jellyfish has
right here it has that Medusa body shape
and it's named after this Greek mythical
figure Medusa Medusa was a woman that
had snakes for hair and if you looked at
Medusa you would turn you into stone
so this jellyfish obviously won't turn
you into stone if you look at it but it
does have a mouth with tentacles around
it just like Medusa has a mouth with
snakes around it so that's why why the
Medusa jelly the Medusa shape of a
cnidarian is named after her and so the
key thing about this body form that
makes it different from the other body
form then we'll talk about in a minute
is that it has a mouth in tentacles
facing downward and it moves around so
jellyfish swim as opposed to this thing
down here so this is the ball of pulp
body shape so this is a type of an enemy
so this is an it and an enemy that only
comes out at night in the Caribbean
so that's places like Florida the
Bahamas and such and what this polyp has
going on it's got a mouth that's what's
in the middle right there
and then it's got tentacles all the way
around the mouth so just like the
jellyfish just like Medusa has a mouth
with tentacles all the way around it so
does a polyp but the difference is that
with the polyp the mouth and the
tentacles are facing up with the Medusa
the mouth and the tentacles are facing
down and in another very important
difference as you can see this anenome
is attached to the seafloor it is stuck
in place whereas the Medusa jellyfish
here
it is swimming around so too many
differences what is that what the Medusa
the mouth faces down as to the tentacles
with the anatomy the polyp the mouth
faces up along with the tentacles facing
up and one swims around and what doesn't
so that's how they're different and this
is again just showing kind of a
different look at each of those so
Medusa on the top again mouth this thing
right here
tentacles right they're facing downward
whereas on a polyp mouth right there
tentacles facing up right there so what
makes cnidarians cnidarians what what
they all share in common so this is then
what a coral and a jellyfish share in
common is they have these these crazy
features known as the mat assists so
that's how one pronounces that word and
so you might remember another type of
nomad assist we talked about that was
the small little air-filled balls that
that some algae use that no mattis's
this is pronounced the same way but it's
spelled differently now in those new mat
assists are used for helping an algae
stay afloat whereas these the medicines
are used for stinging things so why
jellyfish are so unpleasant to touch or
at least a touch their tentacles is
these new mattis's things that they use
for protecting themselves and for
feeding themselves and how to mattis
this work essentially is typically
there's a little like hair at the
surface of them and if you bump into
that hair this spear like thing that has
these nasty barb sticking out of it they
shoot out and so if you've ever gone
stung by jellyfish essentially what
happened is millions and millions and
millions of these tiny little cells shot
their tiny little spears into your skin
so that's why it's not so pleasant
because if you can imagine you know
having millions of tiny little
hypodermic needles shot into your skin
all at once it's not a particularly
pleasant sensation and on top of that
some types of jellyfish actually have
toxins inside of these Barb's so not
only do you have the
the sensation of it not being very
pleasant to have little Spears read unto
you
then you can also have a toxin that
might get my kids you know stuck into
your skin which can be really implore in
some cases can actually even be deadly
so that's what in the matter sisters so
some more things that that unites all of
the various cnidarians so they're all
carnivores right so they're all eating
other animals they all have an
inconvenient from ours so with them they
have just one hole they have a mouth in
that mouth is also their anus it's also
their butt so essentially they eat food
through their mouths they digested it
and then they spit it back out through
their mouths that is that is also there
but all of us or at least most of us I
assume obviously have a mouth and a butt
so we have very a very different way of
digesting our food from them so we're
much less disgusting than they are with
with their mouths being there but they
do have something kind of like a brain
not completely like a brain but like a
brain they have this thing known as a
nerve nest that kind of goes throughout
their body in that is what they used to
move around and to coordinate what
they're what they're doing so if that
was us it would be almost as if as if
your brain was located everywhere in
your body instead of having a brain just
in one place it's all throughout your
body that's what they have some of the
cnidarians that swim around can actually
use that brain that's throughout their
whole body in order to sense light so
some can actually see for instance a lot
of these things will often see so now
we're going to talk about the different
type about a few different types of
cnidarians and the first one that we'll
talk about are these things so this
crazy word is pronounced sky fazil ones
so these are the sky FFA's owns within
the class sky fellas oh wow so these are
what we typically call jellyfishes or as
some people call sea jellies because
there are obviously not fishes there
they're not related to them very closely
so some people call them sea jellies we
can
called jellyfishes now and how these
things kind of operate is that they have
a large Medusa in that will switch to
smaller polyps and then back to a large
Medusa and then back to small polyps so
so that they spend most of their lives
in this shape and this is what we are
kind of used to seeing but I do have
small polyps as well how these things
move around is that there's a ring of
muscles around the bell of there of the
well this thing but it's called the Bell
there's muscles around it and when those
muscles contract they force water and
downward out through the bottom of the
Bell
and that pushes them forward so it's not
a particularly efficient way to swim
around and as a result these things
can't swim very quickly
so in general jellyfish just kind of
drift with with whatever current that
happens to be around them in general
they can't swim against strong Carman's
so like I was just saying they get
pushed around by water so one really
important thing to know is that
jellyfish have tentacles in octopi have
arms which is why active eyes sometimes
sometimes get more credit than than
deadly cnidarians or then jelly fishes
even though even though they shouldn't
get that credit because they don't even
have tentacles so Joel year after year
gets disappointed by the fact that he
doesn't win the the most tentacle award
goes to stupid here's the next group I
want to talk about so these are the the
Cuba Medusa known as the class Cuba ZOA
and so you might recognize the the
prefix here cubes sounds like the word
cube which is a box and so these are one
of known as the box jellyfish you see
they're kind of in this box shape and so
these things say they're pretty small as
opposed to the sky Pisans which have
large Medusa these are pretty small
Medusa but even if they are small they
can oftentimes pack a punch so a lot of
box jellyfish they have no mat assists
that are so potent and toxins that they
can kill humans
so these like I said are the box
jellyfish and and like I was saying they
can kill humans they kill as many as a
hundred
per year in particular there's something
known as an Australian box jellyfish
which is obviously found in Australia
and that jellyfish has enough toxin in
it to kill a couple dozen people so each
one of those tiny little jellyfish that
are maybe like a couple of inches long
they can kill maybe like 30 or 40 people
which is why when people run into them
they you know unless they get medical
treatment really really fast that
they're gonna lot of trouble so these
things are really some of the more
dangerous animals in the ocean people
are oftentimes you know really scared of
sharks they worry about sharks in the
ocean nobody wants to get eaten by a
shark but actually sharks only kill
something like maybe five to ten people
per year whereas these things can kill
somewhere around a hundred people per
year so if you go in the ocean it should
be these you're looking out for not
really for sharks so then that last
group of cnidarians that I wanted to
talk about are what are known as the
anthozoa pnes so these are the anthozoa
pnes which are all in the class in two
ZOA
and these could include the the more
sessile types of cnidarians so things
that are attached to the seafloor so
we're talking about corals we're talking
about sea fans and we're talking about
enemies and so these things they can
either be single or in a colony I'll
describe what that means in a minute and
they have polyps that Lakha Medusa so
what you see here each of these things
only exist in the polyp form they're
never swimming around in a sort of
jellyfish shape and and so sometimes
they can be single and sometimes they
can be in a colony so this for instance
is one single polyp right so there's
just one of it but over in this coral
this coral is made up of many many many
many many individual polyps that are all
in a colony so so that's why corals in
general tend to be a lot bigger than an
enemies because corals are made up of
many polyps whereas the enemy is made up
of just one polyp so these things some
of them have a hard skeleton underneath
so corals like this thing here there
will be soft tissue on the top world the
polyps are but then underneath it
there's going to be a hard skeleton of
calcium carbonate right which is why
which is part of why corals are so
important is because the hard skeleton
that is underneath them is what's is
what forms the foundation for this
entire reef that you see behind there
without these corals that whole reef
doesn't exist so this is showing a
close-up of of a type of coral known as
Mont Astraea this is a coral that is
found in the Caribbean and so this is
showing you how there are all these
different polyps here so that's a polyp
there's a polyp that's a polyp that's a
Paula that's a polyp all of these things
are individual polyps but all of these
individual polyps make up one coral so
these are all a colony of polyps and so
how these polyps work is essentially if
a polyp gets really big then it kind of
splits itself in half and now becomes
two polyps and because it's done that
both of those polyps have the same DNA
as each other they're like identical
twins to each other so they are
essentially clones of each other which
is why we call this a colony so think
colony sounds kind of like clone these
are all individual clones of each other
so that they are a little bit separate
from each other you know they do have
their own mouth and their digestive
tracts so that is separate but they are
connected to each other so there's soft
tissue that connects all of these things
so they're kind of individual then you
know they have an individual amount they
each have their own mouth and gut but
they are all connected to the same thing
so they are all essentially one animal
so that's a close-up of some lobsters
all right here's another one so this is
a different type of coral is found in
the red sea and again you can see these
the individual mouths all along here so
like there's a mouth there there's a
mouth and you can see all the tentacles
there that are facing outward now this
is what a coral reef looks like in the
daytime you know very vibrant lots and
lots of things will live
and here's another type of this is
what's known as staghorn coral so this
is a coral that was really common in the
Caribbean until recently and now sadly
as it isn't so common anymore but you
can see there's a lot of shelter inside
of there and you can't see any fish in
there but there are tons and tons of
fish inside of that coral that are all
hiding within it so let's now go on to
the second group I want to talk about
and these are the tena fours so they are
pretty closely related to it's a
cnidarians in fact in the past people
used to consider them to be the same
thing and they're even called comb
jellies so they're similar to the jelly
fishes of the cnidarians but there are
some really important differences
between the comb jellies which are the
phylum tena fora
and in the cnidarians we just talked
about so what a point difference is that
the comb jellies have these things that
are called ciliary combs that run along
the length of their body right so these
little things that look like tiny little
combs
those are the ciliary combs and those
things they're like little paddles that
they beat back and forth and what
they're essentially doing is pushing
this thing through the water right by
the the effort of all these tiny little
paddles moving that quiz this thing
through the water
so these clubs are for movements these
things like the cnidarians have radial
symmetry so they have a central point
running through their middle and
everything radiates out from that
central point so one really key
difference between the cone jellyfish
and in the cnidarians
is that comb jellies do not have nomad
assists so these things you can pick up
you can touch them and they won't sting
you right so these are the much much
more benign version of the jelly fishes
which is not to say that they that
they're not dangerous to other things
you know so they do have tentacles that
are sticky the wool that will attach to
their prey and used and they use them to
feed on things but they won't hurt you
and so their tentacles I think they're
kind of more or less
like flypaper so you know how you know
if you have flies in your house you
might put you know hang flypaper from
the ceiling the Flies you know run into
it and get stuck this is kind of like
what the the Tina fours do they have
that long sticky tentacle that stuff
gets stuck on to and so these things are
not super diverse there's only about a
hundred species of them they're only
found in the ocean but even though
there's only about a hundred species
they can get really really abundant in
the ocean in fact there's been a growing
concern in the past maybe maybe 10 15
years that in a lot of places where
there used to be lots of fish lots of
tasty fish that we've now even a lot of
or more most of or all of in those areas
where the fish are disappearing we're
now seeing more and more of these comb
jellyfish so it seems like the ocean is
getting more and more gelatinous every
year that where there were once fish now
there are now there are these comb
jellies that are taking their place
which is not a obviously not a good
thing because fish are tasty and comb
jellies
you know nobody eats them they're
basically just like a imagine like jello
that just tastes kind of salty that's
kind of what they I think what eating
them so then the last group that we're
going to talk about in this in this part
of chapter seven are the mollusks so now
we've kind of taken a jump from from
these things these very simple
cnidarians and tina fours that have
radial symmetry and now we're jumping
into these groups of animals that all
have that all have bilateral symmetry so
first let's now talk about the and what
we're essentially going to do is we're
gonna answer what does an octopus a
mussel in a garden snail all have in
common so all of those things are types
of mollusks and so they all have some
things in common because they are all
related to each other
so the Mullis are maybe one of my my
favorite groups of invertebrates simply
because they're they're really huge
there's lots and lots
in their super diverse right so there
are a lot of different ways that an
animal could be a mollusk there's a lot
of different body shapes that they can
have which I find to be pretty
interesting the body plan of mollis all
of them essentially have a head which
you know you can see on this on this
octopus right there there's his head
they all have something that's known as
a foot that is typically on the bottom
of a mollusk so for instance with a
garden snail the thing that the thing
that is on the ground the day that they
used to move around on top of that's
their foot in the case of an octopus the
arms are the foot in the case of a like
a mussel the foot is is part of what
attaches it to the ground
so in general the foot is is something
that is used for for grabbing onto
things or moving around in all them have
a big you know massive thing of internal
organs
you know actually not that different
from us we have a chest cavity a chest
cavity and abdominal cavity that have
our internal organs they have this thing
that has a big mass typically called a
visceral mass that has all of their
internal organs inside in what is
covering that mass of internal organs is
something known as a mantle so that the
mantle is kind of a outer protective
covering of that mass of internal organs
and on some mollusks the mantle is what
actually makes a hard shell so an
octopus doesn't have a hard shell but
something like a clam or a snail has a
hard shell and what actually produces
that hard shell is the the mantle so
some laws have what's known as a radula
and that is a it's kind of like a paint
scraper that you might use for for
scraping paint off off a wall and it's
used for essentially scraping stuff off
of off of surfaces and so that's what a
lot of mosque used to eat small
invertebrates off of the sea floor or
just meat eat small plants off off the
sea floor some things like an octopus
they don't really have a radula so much
they have
of something more kind of like it that
the beak of a bird but some mollusks
have a radula anyway so these things
unlike all the groups we've talked about
until now they do have a central nervous
system that has a brain
in fact probably a lot of you have even
heard of the intelligence of octopi and
some of the incredible things that they
are capable of doing and why they're
able to do that is that they have a very
well developed brain so Mouse all have
brains and they have a lot of the same
organ systems that we have actually so
they have a circulatory system that they
so they have a heart and they have veins
and capillaries and all that stuff that
they that they use for for pumping
nutrients and oxygen and carbon dioxide
around their bodies they also have a
complete digestive system meaning that
they they have a mouth and they they
have a but you know unlike those
disgusting Nigerians that we talked
about a little while ago that their
mouth is there but the the mollusks are
more like us and that they have a mouth
and they have a separate button so the
mouse in a lot of ways are not actually
that different from us you know that the
main difference being there that you
know they mostly live underwater and if
they don't have a backbone
whereas we obviously do have a backbone
and most of us spend most of our time so
we're gonna we're gonna go through a few
different groups of mollusks kind of
starting with you know kind of maybe the
the simpler ones and then getting a
little bit more complex so that the
first one that I want to talk about it
the first group I want to talk about I
want to known as the gastropods so these
are things that are in the class gastro
poda and in this includes things like
snails so there's a what's known as a
cone snail it includes things like
lipids that's what this thing is right
there it includes a balloonies which
which you can find you know on the west
coast of the US so this is a type of
abalone that we
here in California and then we have
different types of sea slugs and so what
the word gastropod means it means belly
footed and so the gastro part you know
refers to the gut like the digestive
tract you know like if you were to go to
like a like a gastropub refers to a
place with really good really good food
so gastro means means stomach or gut or
something like that in the suffix pota
means foot all right so some pod means
foot kind of like a tripod is a is a
three-legged thing used for holding up a
camera so the gastropod means belly foot
and essentially how it works is on
something like this now so all of the
internal organs are in there and then
that sits on top of the foot same right
there with the limpid all the internal
organs are here and that sits on top of
the foot so all these things have
essentially a they have their at their
visceral mass with all of their their
important internal organs and that sits
on top of a foot on a lot of these they
have a shell that's in a coil right the
snails have a have a coiled shell on top
sea slugs don't have any sort of shell a
balloons abalone have you know something
like a partially coiled shell it's about
a full coil but they do have a kind of
circle shaped shell and lipids also have
a have a show so sea slugs like I was
saying a minute ago they've completely
lost their shell
you can probably guess that this shell
is mostly used for defense for keeping
yourself from getting eaten so what a
lot of sea slugs do instead is they'll
have these have these kind of spiny like
things that that have venom in them so
that they're not something that you want
to eat and how most of these things eat
is with their gradual ax so for instance
like this abalone and miss limpet how
they feed is they have tiny little
radula
and they and they kind of use that and
scrape it along the sea floor
so so in doing so what they're doing is
scraping tiny little invertebrates and
little pieces of algae off of the off
the seafloor so this is it's more more
kind of like deposit feeding they're
eating stuff that's deposited on the
seafloor so that's how how things like
this limpid feed now the abalone sorry I
think I mistook a a second ago abalone
don't scrape the stuff off the seafloor
what they actually do is they're their
suspension feeders so they suck in water
they filter the the public particles out
of it and they spit it back out now so
they're filter feeders essentially like
a like a clam or a muscle or or like a
sponge for that matter and then and then
some of these so like for instance this
snail is actually a carnivore so this is
what's known as a cone snail and it
actually specializes in eating fishes so
it has this thing known as a proboscis
which is kind of like its tongue and
what that tongue does is it is it is it
comes out like a little sphere and that
spear has toxins in it that will that
will kill a fish really really quickly
it attacks the nervous system of the of
the fish and and neutralizes it because
fish are not that different from us in
terms of their nervous system these
things can actually also be dangerous to
humans so if you ever see something like
if you're ever in like Australia and you
see something like this do not pick it
up because it could be a cone snail and
if it is a cone snail that it could
actually kill you it could have a toxin
and it's in its tongue that could
actually shut down your nervous system
and it's a good thing to have your
nervous system running so don't let that
happen to you the the gastropods can be
really pretty even if they might be kind
of small they can be really pretty so
this is what's known as a nudibranch
it's a type of sea slug this little guy
which may be maybe an inch long or so so
there's this little gills it's guys a
little butt right there little antennae
uses this since the world around it and
its mouth is essentially underneath
here's another type of
to bring again his cute little mouth and
tentacles little gills right there and
his little butt is right underneath
there and it's got these these nasty
kind of things sticking out that have
toxins in them that essentially
advertise their predators you know hey I
have these toxins you don't want to eat
me even though I'm not protected by a
shell I do have these things so don't
mess with me that's okay the second
group of mollusks that I want to talk
about are the bivalves so these are
things in the class by val vida and so
these include mussels and include
scallops clams oysters this includes
probably the tastier varieties of
mollusks and what makes a bivalve a
bivalve
first of all and how it feeds so all of
these things are filter feeders so they
all suck in water through what are known
as siphons they run that water over
their gills which cleans all of the the
food particles out of the water and then
they spit clean water back out through
through their siphon so they're all
filter feeders and in what we call them
bye-bye valves so I think a lot of you
will will notice it has the prefix bi
which means 2 2 valves so that's
literally all the animals that have two
valves you know so each one of these
things they have two shells you know in
these pictures you can really only see
one you know one shell but I think a lot
of you know that each of these things
will have two shells in the in the the
whole body so the whole mantle cavity is
kind of shoved between the two shells
and I think it's probably fairly obvious
that the point of having those shells is
for is for protection it protects those
soft bits that are underneath and so I
kind of mentioned this a minute ago but
how they feed is they have little
siphons that they use for sucking in
water you know so imagine like imagine
like a snorkel that you would use for
breathing in air while you're while
you're snorkeling around so they have
these little siphons for sucking in
water in those siphon stand run that
water over their gills and so the gills
actually you know have to
options so that you're used for
respirations so you know getting oxygen
and getting rid of carbon dioxide but
they're also used for filter feeding so
any small little particles of food that
are in the water gets wrapped on the
gills and then those are then moved to
the mouth with something that's known as
the the palps of bivalve so these things
they don't have a head like a like a
squid or an octopus does and they don't
have rajala and they don't really need
those things because these are all you
know around the seafloor they don't move
around so much or at all and they're not
scraping stuff off the seafloor so they
don't really need to have a head and
they don't need to have rajala now and
so where you can find these things and
what you could find them doing things
like clams will borrow themselves into
sand so you pretty much only ever find
them in sandy areas hoisters and mussels
will be attached to to hard sea floors
and attached to each other
scallops are the only wants to kind of
swim around and swim is kind of a it's
kind of maybe a little bit of an
exaggeration they swim I'll kind of a
little bit by by opening and closing
they're at their their shells and kind
of forcing water up but it's not as if
they can just you know decide okay I'm
going to move a couple miles away right
now it's a pretty it's a pretty
rudimentary type of swimming but either
way they're not attached to the seafloor
or kind of living in this in the
seafloor like so I want to talk a little
bit about the importance of by vows in
the ecosystems that they are found so
they are water cleaners as we talked
about just a minute ago they filter
water through their through their bodies
and so they essentially clean up the
water and so this is been this has been
kind of a problem for a lot of bays and
estuaries throughout the u.s. because in
a lot of areas the number of bivalves
found in those areas have gone down so
this for instance is a chart showing the
amount of caches of bivalves made mainly
oysters in Chesapeake Bay
so Chesapeake Bay is is on the east
coast of the US it's that day that is
between Virginia and Maryland you know
pretty close to like where Washington DC
is and you can see that the you know in
the 1800's you know up through up
through today there's been a steady
decline in the amount of bivalves that
are in the water and the reason for that
is because people catch them to eat them
so in the in the late 18-hundreds it
started to become a fashionable thing to
eat oysters and so people started eating
lots and lots and lots of them before
that oysters weren't really seen as a as
a as a delicacy or as even anything to
eat at all in fact back in the day they
used to feed Easter's and lobsters to
inmates so people in prison would would
be said lobsters and oysters you know
can you imagine your year in jail in the
in the in year you know you're brought
to the cafeteria and you see that you
have a dinner of lobster in oyster and
you're like I'm gonna god do I have to
eat lobster in oysters again what's
what's with all the water noise stir
it's terrible it's funny funny now
because now those things are considered
delicacies but back in the day those
were considered like the food of
prisoners and of poor people so that's
what was fed to prisoners back in the
day but now they're considered
delicacies and as a result we see this
plot where were the number of oysters in
in estuaries and has gone down a lot
pollution hasn't been so good for them
either certain types of pollution have
really really wrecked them a lot of
these bays have also been developed to
some places where there were five elves
before have now been filled in and and
made into you know maintenance said the
the cities that are around these bays
like for instance the whole like all of
Manhattan you know Newton New York used
to used to be salt marsh and used to the
area where there was a stirs and you
know it's one of the biggest cities in
the u.s. so so anyway these things have
been bad for for these in as results the
the role of oysters as as things that
can clean the water has gone down so
there's nothing filtering that water
anymore which is why there has been some
there has been some efforts to restore
them so for instance something that that
I did when I was in graduate school as I
as I helped to work on a project where
we put boy stores in different parts of
New York Harbor so like in New York
Harbor and then some of like the
estuaries around like Brooklyn and
Queens and in Staten Island and up into
the Hudson River we we were basically
looking to see if the oysters would even
just grow there if the water was clean
enough for them to grow in if it was it
was if it was free enough of pollution
for them to grow and we did find
actually that in some places that they
grew quite well which is basically the
first step you know then the second step
is you know making making places where
hoisters can then live in those in those
estuaries because if they can if they
can live there in a cage like cages that
that we were putting out then they can
presumably live on the on the sea floor
and start helping to clean the wire okay
so this is what's known as a Giant
Pacific clam and I want to talk about
this a little bit because these are the
things that make pearls that you
probably so this is a pearl of a of a
giant pacific clam and what that pearl
actually is is a little piece of shell
essentially so how pearls are made is
that a little piece of shell gets into
the body of the of the clam and it
doesn't like having that little piece of
sand in it but the sand get kind gets
kind of stuck and so what it will do is
it'll grow it'll start growing shell
around that piece of sand and in some
cases it'll just keep growing and
growing and growing that that shell
around around
that piece of sinned so it gets bigger
and bigger and bigger and sometimes it
can get even really huge like this I
mean typically they're pretty small
maybe just like you know at the most
maybe half an inch across but this but
this one was massive right so this one
went to the market in 2016 and it
weighed 75 pounds it was by far the
biggest pearl ever found I think the
biggest one up to that was maybe 20
pounds so this one was huge right so
think of a for a second about what the
value of that thing might have been and
in what it was valued at was a hundred
and thirty million dollars right so just
stupid amounts of money and so that's
what you know so that's what what a
pearl is and so that's I don't know if
it's worth 130 million dollars but
essentially it's just a piece of sand
that a a Giant Pacific clam has built is
built a shell around okay so the the
next group that I want to talk about are
the cephalopods so these are some of my
be the more interesting types of mollusk
because they they're the most active
so this includes the squids it includes
the octopi and includes the the
cuttlefishes it includes this thing
that's known as a nautilus and it
includes a group known as the ammonites
which are where sure actually now
extinct animals but they are the the
ancestor of all of these different
things so why these are called
cephalopods is because the the prefix
cephalo means head in Poteau which we
just talked about in the case of the
gastropods means foot so they are head
footed all right so there's the head and
there's its foot so the arms on these
things is that is the foot so a head in
a foot is what these are made of these
things are all predatory so they will
all attack and kill their at their prey
and eat them how they move around is
with water jet propulsion so on a squid
for instance on the underside of the
squid is its siphon you know not not
that different from the siphon of a
Bible and what it will do is it'll suck
in water
into its mental cavity and then shoot
that water out through the siphon so if
I shooting that water out in a directed
way that's going to propel the the squid
in whichever direction the water is
being forced out so a sweet a squid can
aim it siphon and say this way and
that'll cause the squid to move that
direction whereas the squid can also
turn a siphon around so then water gets
shot out this direction making a squid
go this way so these things are all very
fast very agile predators and they have
a siphon and a mantle so the mantle part
is the top part so that's the mantle
there's the mantle of this one there's
the mantle of the cuttlefish and then
the mantle is under the shell of this
Nautilus and so these things are known
for being very smart so they all have a
very well-developed nervous system they
have eyes that are just as complex as
ours they have a really large brain that
they can use to coordinate their
movements to coordinate the you know the
movement of all their various arms and
if their eyes and to perceive the things
that they see with their eyes you know
so they're they're pretty intelligent
animals especially on the top part of
their bodies they have this mantle thing
that then covers all of their organs so
inside of a squid all of the organs are
right there inside arcticus all the
organs are right there inside of a
cuttlefish they're all up there and
inside of a Nautilus they're all
underneath the shell so these things
they they have a radula which has
basically been conformed into these beak
like jaws so that the jaws of them are
kind of like the beak of a bird really
and in what they use that beat to do is
to is to either crush up prey so like
not alive for instance we'll eat you
know like things like snails off the
seafloor and so they can use that their
their beaks for crushing things or they
use it for ripping you know bits of
flesh off of their off of their prey the
shells of these things are different
depending on which one you look at so in
the case of a squid and a
fish they have an internal shell so both
these things they have this hard piece
that runs along the length of their body
so not a squid that's along here what's
known as the pen runs along that and
then a cuttlefish has what's typically
called a cuttlebone which is along that
the back along there in those things
they kind of function in the same way
that our backbones function they give
them some some support an octopus
doesn't have anything like that so the
only hard part of an octopus are the
other jaws which is why except I can can
fit through really small cracks and
crevices and the Nautilus does have a
hole shell and so when you look at a
nautilus you can kind of see that it's
not that different from the snail and
that's because snails are the ancestors
of all of these things it's just on some
of these they've lost that that shell
that they used to have in there when
they're with their snail in there's a
picture of an octopus so I've seen lots
of massive octopi Whannell what I've
been scuba diving you know mostly at
night because they tend to be more night
predators yeah sometimes I've been lucky
enough to see some that are really
really active like this one was was
moving around on the reef you know
feeding and hunting for for its prey so
octopi are definitely fun animals too so
let's talk a little bit about the
intelligence of of those octopi so
octopi are capable of something known as
social learning so social you can you
can guess you know has something to do
with like Society something to do with
with other individuals it essentially is
is being able to learn by looking at
other things doing something so for
instance we can kind of learn how to do
tasks by watching others do it you know
the the way that you you know start to
learn how to drive a car is by watching
you know somebody else do it
it's the same with octopi not that they
can drive cars but they can watch other
other octopi do things like solve
puzzles inside of aquaria
learn how to do those puzzles by
watching their their fellow octopi so
that's one kind of cool thing that they
can do they're also known for using
tools so there is something known as a
is a coconut octopus and what coconut
octopi do is they will gather coconut
shells on the sea floor and put them
together so they'll get like two pieces
of coconut shells put them together and
that makes one whole home for them so
they will find these things bring them
together and use them as a as a home so
it's a little bit different from say a
hermit crab you know so hermit crabs
they use their their home they use their
shell their whole lives whereas an
octopus will assemble the pieces of
their home and those sometimes use it
and sometimes they won't use it
so that's why we call this tool use
because it's something that's not used
all the time whereas the hermit crab
uses its shell all the time in something
that cephalopods are also known for is
is their uncanny ability to predict
World Cup games so World Cup you know
football us or what we call soccer games
so this is one who's what's known as
Paul the Octopus into the 2010 World Cup
he successfully predicted 11 of 13 games
that his owner had him predict
so essentially what he did is he would
take two flags so you know Spain in
Germany he would have a clam in each of
those crabs I'm sorry a clam in each of
those these boxes that you see there and
whichever one whichever clam Paul went
in ate was his prediction and so we got
11 out of 13 right which is pretty good
that's that's typically a lot better
than that I can do and in predicting
World Cup games okay of course I'm gonna
make a couple joke because cuttlefish
you know do like to cuddle well not
really they're just called cuttlefish
now okay last group didn't wants to talk
about are the kings so they have this
crazy word here so they're called the
class Poli placa for
so let's break that word down so Polly I
think a lot of you know means many so
like a polygon is a is a multiple sided
shape plaque think of like plaque on
your teeth right so it's like a hard
plate on on your teeth
so plaque means plate in forum means to
bear to have something like we talked
about how the porifera like the poor
part needs holes in for our means to
bear so porifera our whole bearing
animals so these are the multiple plate
bearing animals so if you look on this
chitin you see all of these different
things here those are the hard plates of
a of a chitin so it has multiple hard
plates on its back so it has multiple
hard plates that's why we call it poly
placa for so they have a foot underneath
that's like this straight thing that you
see there so they have this foot on the
ground they have a mouth with a radula
they use for for grazing on things that
are on the sea floor
so scraping seaweeds and Inter
vertebrates off of the sea floor
underneath oh and that's all I get to
tell you about about the Nigerians about
the tena fours and about the mollusks so
the next lesson we'll learn about some
other different types of invertebrates
