okay hello everyone this is dr. Lyons
once again and we are in the third part
of chapter seven the chapter all about
marine and invertebrates
in this chapter we're going to talk
about two different groups the annelids
which are the worms and the arthropods
which are the shrimps and lobsters and
things such as that such as this cute
little thing this is a little shrimp
that it tends to hang out on the surface
of corals and I'm not sure what this
shrimp is called that I think but I
refer to it as the popcorn shrimp
because it looks kind of like a like a
piece of popcorn so we're going to be
over in in this top part of the of the
evolutionary tree that you've seen
before so we have so we're going to be
looking at these things here the
annelids and arthropods we have already
gone through these groups and we are
making our way across going in the
direction of the chordates which will be
the last group that we get to today
we'll cover the annelids in them will
cover the arthropods so that the
annelids are what are known as the
segments and worms in the phylum and
Annelida and some things that characterize
them is that they are bilateral so you
see this worm right here it has a
definite left side and it has a right
side they are all segmented and what it
means what I mean by that is that the
body comes in individual compartments so
if you look at this worm along here you
can see that there's a set of legs here
and a set of legs right there in those
legs each are each belong to one
compartment and then next over here then
we have another compartment and then
over here we have another compartment
and over here another compartments and
so on and so forth so the the whole
length of the body has these individual
compartments running running its length
kind of like repeating units and that's
what it means to be segmented is to have
these repeating compartments or
repeating units through the through the
length of the of the body
so these things have a nervous system
then you have a brain that's gonna be
around here on on this guy and they have
a circulatory system and you can
actually see that this dark red line
running along the back of this worm that
is actually what's known as the I
believe it's the dorsal artery so that
is a long artery that runs the whole
length of the body so the worms they
feed themselves in a lot of different
ways so some are carnivores that eat
other animals for instance you see the
big fangs on this thing which is known
as a sand worm sometimes known as a clam
worm I've been pinched by these things
many times because this is a common bait
that one uses for catching a fish on the
east coast of the United States and and
these are obviously carnivores that's
why they have these big pinchers there
are things that are there are worms that
are passive suspension feeders this for
instance is what's known as a Christmas
tree worm it puts its these these gills
that it has these are the gills and it
puts those freely gills out in a out in
the water and any bits of organic matter
like small bits of dead things that
drift by will get caught on the gills
and that's how it feeds others are
deposit feeders this is what's known as
a spaghetti worm so these long things
are its feeding appendages and I guess
they kind of look like spaghetti and
essentially they eat things they eat
small particles of food that are
deposited onto the sea floor that's
again an important distinction between
deposit feeders things that eat things
that are deposited onto the sea floor
and suspension feeders such as these
that eat bits of food that are suspended
in the water so that these things eat
stuff out of the water these things eat
stuff that lands on the bottom of the seafloor
finally there are some segments and
worms that are parasites as well what
gets to those minutes here's a couple of
Christmas tree worms so again these are
suspension feeders right so they put
their their feathery gills out into the
water and wait for particles to drift by
that they can that they
can eat these are also Christmas tree
worms again doing the same thing and he
sort of known as feather duster worms
because they kind of look like old timey
feather dusters that people would use
for dusting they're at their apartments
and such so these are the gills of them
in those gills like those of the feather
of the Christmas tree worms are used for
capturing particles as they drift by in
the in the water so they use these
things for breathing entry so worms can
move around of course in how they do
that is with the use of a couple
different sets of muscles so they have
muscles that run the whole length of
their bodies so they can essentially
constrict themselves from front to back
they also have muscles that that are
running in a circle around there at
their sides so there are kind of these
circular muscles that run a lot around
the body and what essentially they do is
by contracting and in releasing and
contracting releasing circular muscle
and longitudinal muscle that makes a
small anchor that will kind of hold the
body in that place and then by moving
the anchor or along the length of the
body that's how they kind of push
themselves forward through the through
the the sea floor or over the surface of
the sea floor or however they move so
they kind of make this moving anchor
thing that pushes them forward so let's
talk about about a couple of different
groups of of segments and worms
probably the most important one to us
are the Polychaetes because the Polychaetes are nearly nearly all the the
worms you find in the ocean are
polychaetes
or all the segments and worms I should
say that you find in the ocean or Polychaetes
so there's about 10,000 species
most of them are marine like I said and
they feed in a lot of different ways
right so we learned about how this thing
is a carnivore this thing is a deposit
feeder
these are suspension feeders this thing
is what's known as a fire worm it's
called that because if you touch it it
feels like fire all of these whitish
things are these tiny little glass
needle-like things
and if you touch them they get embedded
into your skin not very pleasant
and these things are carnivores they
also eat that they eat corals in fact
and a lot of the segments of worms they
have a really important role in getting
detritus so that is like small dead
things out of the sand and so I'm posing
the question has anybody seen something
like this at the beach if you have this
is essentially the poop of a worm so
what some worms do that live in the sand
is they'll be deposit feeders meaning
that they'll eat they'll ingest large
amounts of sand that has like small bits
of dead organic matter in it and
essentially what they do is a coop out
clean sand so this is saying that's this
been through the digestive tract of a
worm and is now clean of all the organic
matter that had been in that sand and so
with Polychaetes eats the thing that makes
them the thing that distinguishes them
from the other worms the other segments
and worms is they have these things
called Chaetes
so poly as we've talked about before
means many and Chaetes means means hairs
and so the along the length of the body
of Polychaetes are many of these tiny
little hairs hairs that are often called
Seatae so with each Polyhaetes there's a
segments and each segment has a set of
of gills and a set of bristles or Cheatae or
or or what we call Chaetae so the next
group of words I want to talk about are
the beard worms and so this word is
pronounced Pogonophorans so so these
things are called beard worms because
they have they have this this kind of
beard like thing that comes out of them
and so there's a couple interesting
things about them so they don't have a
digestive system so they don't have any
stomach or intestines or anything such
as that they're very simple in that way
what they do instead is they have these
tentacle things which is what you see
here these reddish beard like things
that are sticking out
and what those tentacles do is they
absorb organic matter that's in the
water so they absorb you know you know
sugars and proteins and stuff like that
that's floating around in the water and
so some of these are kind of interesting
and then the in that they have symbiotic
bacteria inside of them so we've talked
about the word symbiotic before and what
it refers to is two things that are kind
of helping each other out in the case of
of this relationship the bacteria that
are inside of them will take chemicals
from the water and they use those
chemicals in order to create sugars
those worms can then use those sugars in
a room in return they give the bacteria
a home to live inside of so that is the
relationship that they have so the
bacteria makes sugar is using chemicals
in the water around them in the worms
provide a home and so these types are
mostly found in the in the deep sea I've
never seen one of these myself because
I've never been in a submarine to great
depth where you would find these sorts
of things but they're pretty much only
found in in deep-sea areas such as what
you see here this is around a deep sea
hydrothermal vent so this is an area
where there's really hot water full of
chemicals coming up out of the sea floor
and the bacteria inside of these beard'
worms are essentially taking those those
chemicals and making food food on which
the whole rest of this ecosystem is
reliance upon by the last group of worms
I want to talk about are the leeches so
these things are strictly parasites and
and by parasites I mean that they live
on either the outside or the inside of
other invertebrates and other fishes and
what they're doing is they're eating
bits of skin they're eating bits of
muscle of other types of tissue they're
essentially eating the the larger thing
very slowly and so it's important to
note that parasites and predators are
different things in general
parasites are smaller than the thing
that they are eating whereas predators
are often bigger than the
that they are eating Leaches have
little suckers that they use for for
holding their prey and kind of an
interesting about them historically is
that they used to be used in medicine so
bloodletting is a was a common medical
practice in the in the darker days of
Medicine essentially a long time ago
people used to think that that if you
were sick and meant that you had either
too much phlegm or too much bile or too
much blood
and so what doctors would commonly do is
if you were sick they would surmise that
you had too much blood so they would
attach a bunch of leeches to your arm
that would then drain a bunch of your
blood out of you obviously obviously we
know now that that's ridiculous that
that wouldn't help but you know we're
talking about the dark days of Medicine
before people knew about about pathogens
and about bacteria and viruses and any
of those things so this is what this is
what used to be done back in the day
thank goodness now we don't do that I'm
pretty glad that I don't live in that so
now we're going to go from the segmented
worms over to the arthropods and so
these groups are our sister groups to
each other
the reason being is that they both have
segmentation but the difference being is
that arthropods tend to have legs
whereas annelids do not so arthropods
are noteworthy in that 75 percent of all
animals on the earth are arthropods the
reason being is that arthropods include
insects insects and and you know things
such as like wasps and ants and all the
various bugs you can think of they're
all arthropods and it turns out that
there is a crap-ton of them on the
planet if you reduced to go to any tree
in the Amazon rainforest and count all
the different types of insects in it
there would be hundreds if not thousands
of different species of insects in each
tree in the Amazon so there's a there's
a huge huge amount of them
they include arthropods include the
insects crustaceans such
Eugene Krabs over here he's a crustacean
and includes spiders and things kind of
related to that so what makes an
arthropod an arthropod is that they have
jointed legs and jointed appendages so
the word arthropod refers to that so the
prefix arthro refers to joints so if you
or someone you know is suffering from
arthritis what they're suffering from is
a condition that affects the joints
which is why it's called arthritis and
we've learned before that Pods refers to
feet or appendages for instance a tripod
is a three-legged object that holds up a
camera so arthropod means jointed
appendages and if you look at eugene
krabs over here for instance you know
that his that he can move his eyes his
arms around his claws around I should
say he can open and close his claws so
there are so those are his appendages
and their joints within them which which
is why he can move them around all of
the arthropods have a hard exoskeleton
made of chitin now chitin is a is a hard
type of protein in EXO refers to outside
so this is a hard outside skeleton as
opposed to the skeleton that we have
which is a hard endoskeleton an internal
skeleton and because these these things
the arthropods have this exoskeleton
thing it means that in order for them to
grow they have to be able to shed that
so in order for eugene krabs that get
bigger and bigger he essentially has to
over time get rid of that hardshell and
so what they do is something known as
molting where essentially the the soft
part of the of the crab or insect or
whatever kind of Wiggles its way out of
its hard shell and it's it's then soft
for a couple of days and then it's and
then it goes back to being hard that the
soft part eventually becomes hard over
time and I have kind of a kind of a fun
anecdote about that when when I was in
grad school the the department that I
was in we had a fish tank that had local
fish and crustaceans and such in it from
the ocean
and there was one large crowd that kind
of bullied around the other crabs so it
would you know he would pull the legs
off the other crabs and like eat you
know eat the legs of other crabs and it
was just a general jerk to the rest of
the crabs until one day that large crab
had to molt and so when it molted now it
is soft in is vulnerable so what
happened all the small crabs eat the
larger crab which I thought was was
pretty awesome poetic justice that all
the small crabs that had been terrorized
by this larger bully ganged up and ate
him when when he when he was soft and
vulnerable you know so so be nice to
people that are you know that are weaker
than you because one day you might have
to molt and when you do they might eat
you anyway with arthropods that the body
is often divided into a few different
parts so they're in in this ant for
instance we have a head we have a thorax
and we have a abdomen
and you can really see the segmentation
there right so we have a head segment a
thorax segment and then we have these
different segments here along the the
abdomen of that you can see the same
thing in in this lobster here right so
we have a head thorax and then we have
these abdomen sections so first we'll
talk a little bit about their crustacean
so that's the first group of arthropods
I want to discuss and that's the main
one that we'll discuss because this is
the most of the arthropods that are in
the ocean are crustaceans so this is the
subphylum Crustacea and so these are a
lot of the shellfish that you would
think of think of like lobsters crabs
shrimps things like that they are
crustaceans so what makes these
different from other arthropods is that
in general they have two pairs of
antennae right so this Lobster has this
longer pair of antennae and then it has
the smaller pair of antennae down there
they all have gills which is why they're
able to live underwater in the case of a
lobster the gills are going to be
underneath the thorax right here
protected by that the thorax and in a
lot of these the head and the thorax is
fused together right so the
the a lobster for instance it can't move
its head around because the head is
attached to the thorax so it's all one
fused thing that is known as the
cephalothorax in this hard part that's
covering it is known as the carapace of
the of this of this so how how crustaceans
feed is through a lot of
different ways so there are some that
are suspension feeders that that are
eating just bits of food that you're buy
there are some that are scavengers such
as this such as this Caribbean spiny
lobster lobsters in general are
scavengers which is kind of funny
because we consider them to be such a
food delicacy but they are totally
bottom feeders they just eat whatever
dead crap they can find on the seafloor
but nonetheless we think they're great
there are some crustaceans that are
parasites there are some that are
carnivores that will actually hunt and
kill live things so there's a lot of
different ways that crustaceans survive
and in a lot of why there's such a
prominent group in the ocean is because
they have a lot of specialized
appendages that allow them to feed allow
them to swim allow them to carry eggs
around by having all those different
appendages that they can use in those
appendages that can have evolved
crustaceans have really kind of filled
in a lot of the available niches that
the things in the ocean can have by
Niches I mean like ways of living like
things that you can do to survive and
crustaceans fill a lot of those one
thing about crustaceans that will become
important when we talk about the
barnacles is that they have internal
fertilization so they have they have sex
you know just like a lot of other
animals including us that you can think
of right so eggs and sperm have to be
each other
here's one of my favorite types of
crustaceans this is a picture I took in
Indonesia
this is what's known as a cleaner shrimp
what it does is it it hangs out on anenomes such as this and essentially
fish will come by that that wants to get
cleaned by that I mean have parasites
removed from them so this little shrimp
will go into the mouth
of larger fishes and remove parasites
from them so this is a another symbiotic
relationship where the small shrimp gets
a meal and the larger fish gets I guess
the parasites removed from it now here's
another one of those such cleaner shrimp
living inside of an Anatomy this one
though has some eggs which you can
actually see it so this is a pregnant
female shrimp this is one of my favorite
types of crustaceans it's probably hard
to see what's going on here but this is
the one of the claws this is another
claw
here's an eye and there's another eye
and and this thing is covered in all
sorts of stuff because this is what's
known as a decorator crab so decorator
crabs they find things that are on the
sea floor and they attach them to their
shells their shells have these tiny
little hooks on them almost kind of like
velcro and I think you can probably all
guess that the reason they do this is
for camouflage by covering themselves
with bits of stuff from the sea floor it
allows them to blend in and make it
makes them very very hard to notice some
of you may be maybe thinking about the
movie Moana there was a there was the
the shiny crab played by the the New
Zealand guy Jermaine Clemente that
character the the shiny crab was based
on decorator crabs but typically
decorator crabs don't cover themselves
and shiny stuff that would make them
noticeable they cover themselves in and
stuff like algae and sponges and things
like that to make themselves blend in
let's talk about some of the different
types of crustaceans the first one I
want to talk about are copepods and they
are noteworthy and that they're the most
abundant animals on the entire planet if
you were to go out to the ocean
virtually anywhere in the ocean and and
just take a scoop of water in in a
bottle you would find hundreds of
copepods they are just absolutely
everywhere super super abundant and
these things occur they can be
planktonic meaning that they drift
around in the water that can be benthic
meaning that they hang out in the sea
floor there's some that are found
fresh water there's some that are even
found in the canopy of redwood trees in
Northern California so somehow a type of
copepod evolved the the specialized use
of the canopy of redwoods and so you
find them there you know hundreds of
feet off the ground inside of redwoods
these things they what makes them
different from some of the others is
that they have a super long antenna
that's oftentimes as long as their body
is and what they use that antenna for
aside from sensing the world around them
is they use it for swimming so they can
beat this antenna back and forth and
that propels them forward through the
water kind of like a like a rower will
will pull oars through through water in
order to push themselves forward and how
these things kind of survive what they
do to feed themselves as they eat to try
this meaning like if it's small bits of
dead stuff on the sea floor or they'll
eat suspended particles out of the water
so in general they're at their deposit
feeders in there and their suspension
feeders ok let's talk about the
barnacles a little bit so barnacles are
very common on on sea shores like like
in California and in what barnacles do
is they is they essentially attach to
hard surfaces so like these barnacles
here they're stuck in place they can't
go anywhere right they're stuck right
there so they are sessile they have
these hard plates all around their
bodies that they that they use for
protection and they are past those
suspension feeders so what they do is
they is they wave their their feathery
appendage in the water in order to
collect bits of food that they come by
and and with them probably something
really noteworthy about them is that
they have the largest penis of all
animals sorry that should say the
largest penis of not off the largest
penis of all animals and in what that
that means or why that is is because
they are stuck to rocks right this
barnacle can't just go over here to this
other barnacle for them to
so the how they've kind of dealt with
this situation is if they have a really
long penis so essentially this barnacle
what it will do is it'll extend its long
penis out of its shell
insert its penis into this barnacle
nearby its neighbor and that's how they
copulate and and with barnacles
they are simultaneous hermaphrodites
meaning that they have both both male
and female parts so each one of these
can reproduce with the other they just
have to have a long enough penis to
reach there at their neighbor in some
barnacles the penis is 20 times the
length of their body so just imagine
that 20 times the total length of their
body so it's not as if they have penises
that are larger than like those of a
whale but relative to their body size
they have pretty huge penises so that's
that's probably the most noteworthy
thing about about barnacles and probably
something you didn't think you liked
anyway that's done so let's talk about
the isopods so so what makes them
different from the others is is that
each of their segments are roughly
identical to each other right if you
look at each of these segments it almost
kind of looks like those of a worm where
they're they're pretty similar so the
prefix iso mate means the same so all of
their their their segments are pretty
similar to each other and their legs are
pretty similar to each other so these
things are known for being really
disgusting parasites so they will attach
to the outside of fishes and you know
eat their blood and eat their muscle and
the tissues and whatnot probably the
worst one of these something that is
truly disgusting is there is a type of
isopod known as a tongue eating louse
and what that tongue eating louse does
is it goes into the mouth of a larger
fish it eats them the tongue of the
larger fish and then it assumes the
position of that tongue so now that
isopod lives inside of the mouth of a
fish in it and it takes the role of the
of the tongue it fills that space so
essentially any any
food that that fish eats now that I
support is right there in the mouth and
can eat some of its food so the I supply
just spends the rest of its life in the
mouth of that fish just eating the the
fish as food as the fish is is feeding
so pretty pretty disgusting so if you
see one of these things coming towards
you in the ocean you know make sure to
close your mouth you don't want one of
these in your you know you don't want
one of these eating your in your food
and being stuck inside your mouth I'm
joking of course these things wouldn't
actually go inside of you but if you're
a fish you know if there any fish out
there listening to this lecture then
make sure to watch out ok another group
of crustaceans I want to talk about are
the krill so these are what are known as
he faces and the you faces are small
shrimp-like crustaceans that specialize
in eating plankton and what is probably
most noteworthy about them is that they
can get to be super super abundant so
there will be billions and millions of
these things that are about maybe an
inch long or so they tend to be in cold
waters in there the whole reason why
whales will migrate to very cold waters
is is because there's a trick you know
even though each one of these is pretty
small
there's a tremendous amount of them here
so there's a lot of food right here for
something like a whale to come along and
eat so particularly the baleen whales so
things like like minke whales and blue
whales and humpback whales they will
migrate to cold parts of the planet in
order to feed on on these on this krill
ok and then probably in terms of you
know of ocean functioning or in terms of
the many more in terms of the
crustaceans that we know of we should
talk about deca pods because most of the
crustaceans that you would typically
think of our decoupage so these are like
shrimp they're lobsters the crabs things
such as that so these are the largest
group of crustaceans so they make up the
bulk of the crustaceans that exist out
there while they're air called deca pods
is because they have ten feet so the
prefix that means 10 pod means foot
as we've been talking about so each of
these have five pairs
of Limbs so for instance if we look at
this crab over here which is what's
known as a Dungeness crab we see one two
three four five legs there and then one
two three four five so they've got ten
ten legs total of course sometimes those
legs are modified so in the you know in
the case of this crab you know its first
two legs have been modified into claws
you see the same thing with this lobster
first two legs have been modified in
front claws over here you might think
this looks like more than ten but these
actually aren't legs here these are what
are known as swimmer runs these are the
the legs of that shrimp right there so
what these things do in order to feed
themselves is they're scavengers right
so like these things crabs and lobsters
in general are scavengers in dead stuff
off the seafloor some are carnivores
we'll get some one of those in a bit
some are our detritivores which more or
less means that they're deposit feeders
that you just dead you know small stuff
that don't lands on the seafloor
and in the case of a lot of these the
first pair of legs as I mentioned
earlier are often bigger in and then
used for feeding or used for defense so
for instance the on the typical lobster
that you would find if you went to the
Red Lobster or seafood restaurant or
whatnot is that the this Lobster that
you find on the east coast of the US has
these big claws in front and those claws
are quite powerful when I was a kid my
dad used to keep used to have lobster
traps for catching lobsters when when me
and my brothers were young and in the
biggest one he ever he ever caught
he wasn't very careful with and it
pinched him and I imagine there was
quite a lot of profanity maybe not
appropriate for the young ears of a very
young dr. Lyons but anyway I think me
and my me and my brothers apparently
thought it was pretty damn hilarious
which is probably why my dad didn't
catch didn't keep catching lobsters for
too long after that kids are jerks
so then so then with these things the a
lot of times the head and the thorax are
fuse kind of like I was saying before so
on this lobster here's the head here's
the thorax those things are fused
together
in the case of crabs the abdomen is also
fused so here's the abdomen on a lobster
in this triangular thing here that's the
abdomen on a crab so their abdomen and
the thorax in their head are all fused
together so you might notice that that
with these two crabs these are both what
are known as green crabs you notice that
the triangle thing that the abdomen is
kind of shaped differently on the two of
them the reason being is that one is a
male and one is a female and so the
females are the ones that carry eggs and
they carry it in their abdomen so then
you could probably guess that the female
is this one down here it's got a wider
abdomen which allows it to carry those
eggs whereas the male doesn't need to
have a wide abdomen because it doesn't
need to carry them around so sometimes
in and I've found this many times myself
have found crabs that have females that
have a pouch of eggs essentially
underneath the abdomen here and I've
seen this some lobsters as well female
lobsters will carry eggs underneath
underneath the abdomen to go back to
that story I was telling a minute ago
about about the lobster that pinched my
my dad's finger when I was a young kid
that lobster was a female and had a
bunch of eggs
meaning that he couldn't even eat the
lobster when you touch in general when
you catch lobsters that have eggs you're
required by law to let them go so so I
think that was a pretty bad day for her
from my dad's career as a lobster
fisherman because he got pinched his
kids laughed at him and it wasn't even a
lobster that he could that he could that
he could keep okay
there's a couple of a couple of
different types of decapod I wanted to
talk about specifically because they
have interesting features pistol shrimps
are definitely one of these so with this
shrimp here you can see that it's got
one large claw and then one smaller claw
and so what that one large claw does is
it kind of fires what's known as a
bubble bullet so it will kind of snap
this claw back and snap it shut it's
super super fast speeds and by doing so
it it releases so much energy that it
sends this little kind of bubble bullet
that it uses to
it's prey so these pistol shrimp in a
way that they kind of shoot their at
their prey so they use it to kind of
shoot into in to decapitate their their
or incapacitate their their prey
another things that that these pistol
shrimp are known for that I that is
pretty near and dear to me is that they
have mutualisms with larger fish so
what's going on here is you see a pistol
shrimp down here and up here is a larger
fish known as a goby fish and what
happens is this pistol shrimp is really
good at making a hole in the sand so
there's a whole like burrow underneath
here that that it can hide inside when
there are predators around
however this shrimp you're looking at it
and you're not really seeing any eyes
and the reason is because they're
evolved for a below-ground lifestyle so
they have lost their eyes and lost their
vision so anytime this shrimp comes out
of its little hole to feed or to or to
push sand out of the hole
essentially it's vulnerable to predators
because they cannot see them coming so
that's where the fish comes into place
so the fish has these big eyes which you
can see and what that fish does is it
acts as a lookout for this smaller
shrimp so anytime there is a predator
outside this fish will kind of wave its
little tail back and forth in the shrimp
has its antenna on the tail of the fish
as you can see there so if it feels the
fish waving its little tail back and
forth the shrimp knows that it better
get back in the Burrow otherwise it's
going to get e'en so the shrimp makes a
makes a little burrow in the sand and it
allows this fish to live in the Burrow
so they're kind of roommates and what
the fish provides in return is a warning
signal for when there are predators
around so this is a classic example of a
mutualism or a symbiosis where they're
trading two different benefits right so
there's protection that the that the
fish provides is being exchanged for a
home which the shrimp provides and this
is really near and dear to me because
this is actually what I studied my PhD
on so I've spent hours and hours and
hours watching these things and kind of
working out the relationship between
these things okay so a lot of arthropods
are of in decapod specifically are of a
lot of commercial importance so what
you're looking at here this is what's
known as the California spiny lobster
they don't get quite as big as the like
American lobster that you find on the
East Coast but nonetheless they're
they're relatively big pretty tasty
lobsters and so I want you to think
about what sort of economic impact this
lobster might have right so how much
money do you think the the lot the spiny
lobster fishery might generate in
California each year and so like how
much money is made by people going out
and catching these things and so the
number is roughly somewhere in the order
of like fifty to sixty million dollars
per year so the commercial fishery
meaning meaning professional fishermen
like professional commercial lobster
fishermen will go out and they when they
catch they catch lobsters and they sell
them to you know to markets and that
generates somewhere around 20 million
dollars a year in the recreational
fishery meaning just regular people like
you and me not not could not
professional fishers people like us
going out and catching these things
generate something between 30 and 40
million dollars per year
right so actually a pretty important
fishery on them okay one less type of of
crustacean that I want to talk about are
the mantis shrimp and so if you are a
small crab this would this site of this
thing would strike terror in your in
your heart the reason being is that
mantis shrimp they are really really
effective predators so why they're so
effective is first of all they've got
really crazy vision so they have they
they can see more color than us the
reason being is that they have an extra
set of cones that we don't have so
inside of your eyeball in your retina
there are rods and cones rods and cones
are the cells that your that your eyes
use to detect light and cones are the
types of cells that are used for for
detecting color in the case of a of a
mantis shrimp
they can they have more types of cones
than we do so they can see more light
than we can on top of that they can move
these eyeballs all around in all
directions so they can see around them
really really well so that's pretty cool
but then the thing that makes mantis
shrimp really different from a lot of
other type of crustaceans is how they
actually you know killed their prey so
here in there they have these cloths
that are modified into little boxing
gloves
so essentially what they do is they
corner their prey and they just beat the
crap out of it so imagine like Mike
Tyson just beaten the crap out of like
some poor defenseless
person this is what these things do they
are they're mean bullies that just beat
the crap out of their prey and then and
then eats their eat their prey so like I
said if you're a small crap you would
want to avoid these things as far as we
go you know these things are no longer
than a foot so they're not really a big
threat to us okay so there is one other
type of marine arthropod that I want to
talk about a little bit in its these
kind of interesting things so these are
what are known as horseshoe crabs so
they are a completely different group
from the crustaceans so they're not
crustaceans they're actually more
closely related to things like spiders
and ticks and scorpions and things like
that so this is the the class Merostomata and in some important things
about them is that first of all they are
not true crabs so like eugene krabs he
is a true crab he's a decapod crab of
the crustacean group of arthropods
whereas these things are not that they
are not true crabs like I was saying
before they're more closely related to
spiders and in ticks so probably the
most interesting thing about these
things is that they are old so this is a
fossil of a horseshoe crab and you can
see that this fossil looks pretty
similar to what they look like now so
these things have been around for a very
long time some somewhere around 450
million years in over that entire period
of time they have stayed relatively
unchanged
right so they've have pretty much the
same exact shape in lifestyle that they
had 450 million years ago so they have
just they have this really simple but
really effective way of living and they
have just kind of stuck with that for a
long period of time right so these
things go back you know longer than
sharks larger than dinosaurs in in in
that whole time they've stayed unchanged
so these things you're not gonna be able
to see one over here because in
California we don't have them the
nearest place where you would see one of
these is on the east coast of the US so
where I grew up near Boston I would see
tons and tons of these when I was a kid
and you'd see them on the shoreline kind
of clamoring around kind of kind of like
this when you see them all kind of piled
up like this essentially as what's going
on is its reproduction time so these are
all males and females that have all
clambered up on the beach and they're
all getting ready to reproduce so how
these things feed themselves is they're
scavengers so they just see whatever you
know dead stuff they can find on the on
the sea floor yeah so those are the
horseshoe crabs and that's pretty much
all I got to tell you about the annelids
in the arthropods so in the the next
chapter we'll get into the last groups
of of invertebrates so we'll talk about
the the echinoderms and then we'll get
into the chordates that don't have a
backbone
