Hey good morning everybody happy Friday you made it through another week so great job you guys are doing awesome on that note I hope you're all having a great Friday and that you have some wonderful Easter plans this weekend even if it's just a simple Sunday dinner like every other week with your family and I know this can be a challenging time considering the fact that we may not get to spend it with the friends and family we normally would on a holiday weekend but you know reach out pick up th
e phone give them a call it means so much I know that we were definitely looking forward to seeing my stepdaughters next week but because of all this they're not able to come out hopefully we'll get them out soon but I know we're kind of a little sad but we're gonna hang out together and make the best of it and give them and have a good FaceTime call on Sundays so I'll have that to look forward to okay so what do we have in store for lecture today so we are gonna just start off with a few update
s like normal I made this kind of little outline about all the assignments that we have going on we have a lot of assignments that are kind of kind of and their due dates are coming up next week so just so you have kind of an organized list the assignments that you have do a Monday those are the first assignments or that are coming up do they are the graded discussion board from lecture this week which is due April 13th at 11:59 p.m. you also have the LearnSmart assignment for chapter 26 which i
s gonna cover invertebrates that is also due on Monday April 13th the next assignment that we have do is Wednesday April 15th at 11:59 p.m. this is the connect homework from chapter 23 so covering that chapter on microorganisms this is again a graded assignment meaning that the your score for this assignment is based on the responses to the questions in the homework assignment the kind of next assignment we have due which is a week from today Friday April 17th at 11:59 p.m. is that unit 2 bonus
assignment so that'll be due and then I will start updating everyone's scores for their unit 2 exam and then the last assignment that is kind of out right now is that next LearnSmart assignment which will be due Sunday April 19th at 11:59 p.m. covering vertebrates so those are the kind of list of assignments that you guys have you guys should be kind of working through and they're kind of all do spread out over next week so just know that that's coming up and that if you have some time this week
end then you can knock a few of those off its gonna make next week much smoother for you guys ok and then my last announcement is that I have updated the YouTube video from Wednesday's lecture with the edited transcripts for you guys so you can check that out and I've updated all the links on our canvas page so those are out there for you as well okay so for lecture today we are actually going to start our next section in our diversity unit that is going to focus on animals and as we as people a
re animals I'm going to try to sprinkle in some kind of interesting comparative anatomy in to that as well as we move through kind of the major phyla the invertebrates and vertebrates so we're gonna spend some time as we introduce this topic talking about why animals matter why we as people should devote and why we should devote some time in this class to studying their evolutionary history and their biology and as kind of that justification we're going to talk about some biomimicry which is sup
er super cool so I'm excited to talk about that we're going to talk about some of the general kind of broad characteristics that scientists have used to define what an animal is and what it make what makes animals different than other living things like the microbes and plants we're then going to talk about some of the driving forces that have influenced animal evolution and have kind of led to the hypothesis of how true multicellular organisms kind of arose and then begin to talk about kind of
some of the primary body plans that scientists use to help classify animals into different phyla okay so again why why do we care about animals I like to start off different subjects with how they relate to us we as people are very egocentric we so having kind of an understanding of how and why animals are important to us kind of helps justify why we devote time to studying their evolutionary history and their biology in this class so for starters animals are a food source either through direct
harvesting like this beef cow you see here in this image or whether it's these fish or crustaceans that you see in this fish counter are kind of in the lower right hand corner of this image or it can be products that animals produce that we rely on things like milk and honey and eggs therefore to kind of help support and sustain our own selves there are whole fields of science that is devoted to kind of not only understanding the their ecology but their biology in order to help us sustain these
food sources so for example there are whole fields of science that are focused on dairy cow management so not only the business of learning how to run a farm but all of the biology that goes behind it so things like studying the reproductive cycles and their reproductive physiology since cows only produce milk after giving birth you know understanding what qualities generate a healthy heifer which can lead to high reproductive yields and help them produce a high nutritional nutrition rich milk a
re all extremely important and I'll give you an example so for example 50 years ago dairy cows the average dairy cow would have ten lactation periods so that means that dairy farmer was able to impregnate that cow ten different times and they typically have a lactation period of ten months and they were able to do that ten consecutive times now the average dairy cow due to inbreeding and other environmental environmental stressors as well as stressors that are associated with a much larger more
industrialized Eric dairy industry has led to these cows only having about three for lactation periods in their lifetime before it becomes more costly to maintain that cow than the amount of milk that it's producing so understanding how we can improve their reproductive health as well as different feed products and behavioral augmentations that we can make in the in their maybe in how they are housed or how they are pastured that help ensure that their milk yield is high is stuff that these many
scientists are studying which is super super cool I think another kind of example is that there are fields of science that are devoted to studying how meat like in the lake from this beef cow here how after that cow is harvested how that meat breaks down so there are a whole there's a lot of studies that are focused on looking at proteases which are enzymes that break down muscle tissue and how things like the slaughtering process how that meat is stored and packaged how that influences the amo
unt of those proteases and how it degrades that meat product because this is all directly related to the quality of meat that is put on your plate so there is a ton of science that goes into that glass of milk that you have in the morning or that steak that you eat for dinner other examples are we need to understand in all these fish that are harvested like in this blower image here understanding their biology helps us to set sustainable fishing yields to ensure that those resources are kind of
maintained so in addition to animals being a food source like all these examples we just talked about another main contribution to our lives is that they offer a ton of competitive companionship they offer enrichment in our lives about 62 percent of households have pets whether it's a horse or a dog or a bird or a lizard they all provide us with some benefits that have been scientifically proven things like people with pets tend to have decreased blood pressure it helps buffers stress in our liv
es families and individuals that own pets visit the doctor less than individuals that don't they have fewer cases of depression less anxiety they have a higher immunity so there's all these benefits to having a pet and in fact during this time of coronavirus and as people embrace this social distancing pet adoptions and fostering across the United States has gone up 700 percent um and on that same note there's a huge amount of science that has gone in into this into understanding breeding practi
ces in order to produce the large amount of domestic and agricultural animals that we have out there as well as understanding their behavior and in fact they are just darn cute how can you not think that that is fun hat this is Zoe here and then here's Bosco how can you not find look at how cute that is how can you not find that just warming your heart kind of helps you get through the day I know that it helps me and then lastly not only are they a huge role in our personal lives but they play a
huge role in this science and technology fields animals particularly mice and rats make up 95% of lab animals so they are organisms that we use as test subject as well test subjects as long as well as model organisms we base a lot of our medical research on and there are several reasons why mice and rats are so commonly chosen one is that they're fairly easy to maintain and house they're adaptable they have an our selected life history like we talked about earlier in our ecology unit so they re
produce very quickly and they have relatively short lifespans which gives us the benefit of being able to observe several generations over a relatively short amount of time in addition they are relatively they have many characteristics that are similar to us their genetics are very similar we share about 95% of our genes with mice and a lot of their behaviors also closely resemble those of humans and as a result of that they make an ideal test subject and not only that but we can breed these mic
e so they are virtually genetically identical and this has been a huge benefit to the medical field this helps us create medical trials where we can help produce more uniformed results because all of our test subjects are identical which is much different than when you move into human testing where every individual their genes their health background they all influence the results of that study and what's also neat is we have been able to make these genetic resemblances even stronger by breeding
genetically altered mice where they can carry genes that are similar to those that cause diseases in humans and we are able to turn off those genes so these are called knockout Mouse or mice where you can use them to we evaluate the effects of different chemical compounds and drugs so all very important important parts to studying medicine so and in addition to using them in medical research we have also discovered many different chemicals and compounds that animals produce that nap naturally t
hat benefit us and one of the examples we talked about earlier were those horseshoe crabs where we collect where we harvest them and collect their blood for those amoeba sites which produce that compound known as chloride again and it allows us to test our different medical products particularly injectable drugs as well as medical equipment for any kind of bacterial contamination so therefore we've all directly benefitted from these guys any one of us that has had a shot in our lifetime or has s
ome kind of or has some kind of medical equipment whether it's an IV or catheter or whatever have benefited from these compounds in that horseshoe crab blood but it's not just compounds that animals make that are useful and there are o different fields of biology that kind of relate the physical characteristics that we see in animals and have studied those in order to benefit people so and this is this is really what's amazing is that animals because they occupy such vastly different habitats th
ey kind of collectively acquire huge diversity of characteristics that kind of help them survive and thrive and all these different habitats and we can learn so much from these physical structures and in fact like I mentioned there's whole fields of biology that kind of investigate this and this feel is kind of known as bio mimicry so this is where we use those biological organisms those biological systems as models for product design and creation so basically we can use these living organisms f
or inspiration in building new technologies and I have some really cool examples that I want to share with you because I think this stuff is just so neat and in fact kind of cool side note that I learned while I was putting all this stuff together is that ASU has an on-line master's degree in bio memory I think I think it's online but we have a master's degree and by biomimicry so this is something that you see and you're like oh my god that's so cool we have a master's program in that which I j
ust think is amazing so this first one that I'm going to talk about is actually a product that was developed by at collaborations between a gecko biologist and a polymer science from a college in my hometown and the product that they created was that they named geckskin and this kind of all began with understanding gecko biology and one of the coolest things about geckos is that they can climb up vertical walls and hang upside down by just their toe pads so understanding how this they've achieve
d this adhesive or this adhesion to these surfaces without secreting any kind of sticky substance has been a really interesting field and one that we have spent a lot of time trying to adapt and what we have learned from this from this remarkable kind of adhesion power from these geckos is that this stickiness if you will kind of has come from these nano structures on the geckos toe pads and it's these nano structures that has kind of allow allows them to climb up these vertical rock walls and h
ang upside down and basically what they are if we were to zoom in on a geckos foot with an electron microscope that they have these tiny hairs that cover their toe pads that are called seat a and these seat a the end of these seat a branch off even far even more creating even more bristles that are called speck Tula's and basically because of all these very very tiny nano structures they allow the Gecko to get incredibly close to the substrate that there are so they are able to interact with the
substrate that they're climbing on at a molecular level and which is really really neat and although in general these kind of types of molecular interactions are comparatively very weak if we were to compare them to a molecular interaction like an ionic bond which is between two charged particles like a positively charged sodium ion and a negatively charged chloride ion creating kind of sodium and chloride and they're bonded together by those differences in electronegativity but it's the fact t
hat that these spatula bristles there's so many of them they that they create millions and millions of contact points with the surface that collectively those interactions are additive and as a result become very very strong and what's really cool about this research is that it wasn't just this toe pad structure that was important to this adhesive quality of geckos it was the structure of their entire foot and this is what one of their really cool discoveries is that it wasn't just these tiny sp
atula on gecko toes but it was also in combination with these very stiff tendons that lay within the skin of their toes and it's these stiff tendons that provide the force that push those special up against the surface creating those very those molecular interactions with the surface so do you kind of think about it if you were to put your hand up on a flat surface not every portion of your hand would touch there would be gaps in between in between your hand and the wall so a gecko is very diffe
rent is because of all those nano structures when they put their toe up against that surface they are in the pressure from those tendons kind of push that push all of those nano structures into that wall creating this kind of powerful sticking force and as a result of this they have taken that biological structure and modeled a new [Music] kind of product from this so basically what they've done is they've taken a stiff fabric like Kevlar which is the fabric that's used in bulletproof vests whic
h is what they've used to kind of mimic the tendons of those gecko toes and they've woven that with into a softer polymer which is kind of equivalent to those spatula on those gecko toes and as a result of this kind of like woven fabric which is an example in this image here where you have those thicker Kevlar tendons in this fabric of softer polymer that this allows you just like the Gecko toes this substrate this fabric kind of drapes over the surface creating very intimate contact and as a re
sult of this it can also produce a tremendous force so what you can see here is we have about an index card size of this geckskin that is able to hold up to 700 pounds and what's super cool about this is not only it can hold all of this weight but just for the simple twist you can remove this geckskin from the surface without leaving any kind of residue and you can use it over and over and over again so this is even different than like a command hook where as in yeah we can take the command hook
off the wall but that sticky adhesive stuff can only be used once this stuff can be used for Pettit of Li you can redrape this fabric over a surface and you will and that adhesive quality will kind of get turned back on as you will and you can actually buy these so if you were to go online and check search geckskin you can buy kind of command hook like products that are made from this technology so super super cool so another example that I have is sharkskin this is another very cool biological
structure so sharks have very unique scales so here we have kind of a microscopic version of those scales blown up and what I want you to see is that they have these very distinct ridges on them so not only do they overlap but they have these ridges that kind of face backwards that kind of go from the nose to the towards the tail and these structures are really really important for several reasons one of them being is that they actually produce disturbances in the water around the shark so kind
of helps push water away from the shark kind of allowing them to slip through the water more easily creating less drag so we've taken this technology and we've used it these structures and one of the and can you guess what one of these how we've utilized these structures have we talked about slipping through the water more ease you guess so one of the products is actually speedo use these to develop different forms of swimwear for competitive swimmers which were known as Baskins and in fact the
very first line of these I think were developed a line of full body suits for the 2008 Olympic Olympics where these suits had these nanostructures that kind of resembled sharkskin in order to help push the water away from the swimmers bodies kind of reducing that frictional boundary layer and allowing them to move through the water more efficiently and in fact that year in the 2008 olympics 98 percent of the middle of the medal winners were swimmers that were wearing this shark skin inspired sw
imwear and in fact for the next Olympics in 2012 this technology was banned as it was considered like an enhancement so it was kind of categorized the same way as like different types of drugs are or blood doping is where it was considered to be an enhancement to an athlete's ability so wasn't measuring how how good they were as an athlete so they removed them and you could not wear them so kind of cool on that note it's not just swimwear that has utilized these shark this technology of sharks s
o there's a whole company that has known as sharklet where they've actually used shark scales to help make resistant structures to prevent fouling on different particularly bacteria fouling and this all came about first off as one scientist was starting to try he was hired by the Navy in order to help develop some kind of anti following coating for ships in order to prevent algae and barnacles from forming on the bottom of ships because it's very expensive to pull the boat out of the water and r
emove all of these organisms from the bottom of the boat and one of the things that in his research what he noticed is that sharks you know different than whales often you don't see them with any kind of fouling organisms like algae or barnacles that kind of grow on top of their bodies and he discovered that this is most likely due to kind of the shape of those scales that discourages microorganisms from settling on them so this kind of began this idea that this net these structures on these sca
les kind of prevent the settlement of microorganisms kind of transitioned into the medical field where they began to synthetically develop products or different films that kind of had a nano structure that resembles that of sharkskin that kind of had these these patterns so here we have our shark skin on the left and here we have the kind of micro patterns that sharklet has created in different types of products and they've used these primarily in the medical field so they've developed different
kinds of sticky films where these textures on these films kind of prevent or control bacteria from settling on surfaces so instead of using any chemicals or antibiotics you could simply place these films like peel and stick films on the surface of high touch areas like light switches or doorknobs or handles of medical beds or whatever to kind of prevent the accumulation of or bacteria on these surfaces so it kind of these structures these nano structures kind of prevent bacteria from forming bi
ofilms and kind of keep them from colonizing and they've done tests where they've grown bacteria a flat surface and then one with these sharklet textures and the amount of bacteria is about 85% less and then the kind of next step of this is not only do we want to do it on these structures that are high touch but can we develop medical equipment like catheters that have kind of these different textures on them in order to prevent things like catheter-associated UTIs so other really super cool tec
hnology another one is this company that has developed this product called whale power so what's really cool about whales is that for their size they're very efficient and fairly maneuverable within their aquatic environment and one of the thoughts of this is that these tubercles which are kind of these bumpy edges on whale fins have been found to possibly modify the flow of water over their fins that helps reduce drag and increases lift in these guys so we've taken this same technology or this
company called whale power has which is a canadian company and they developed wind turbines that have these kind of tubular oils kind of modeled after these whale flippers on them where you have these like kind of bumpy little ridges that kind of help push the air over these propellers more efficiently and as a result the efficiency of these wind powered turbines is about 20% higher they've decreased noise that they make by 2% and they've increased the longevity of those wind powered turbines so
it takes a lot of energy to move those through the air a lot of power from that from that engine so as a result of making the propellers more slip through the air more easily they've increased the life of these wind turbines by three to six years so how cool is that okay my last example and I promise we'll start talking about some other biology is that we've also changed the structure or of high-speed bullet trains to mimic different animals so look so the issue with bullet trains is that they
are extremely loud and part of this comes from the fact that they are moving so fast that they displace the air ahead of them so basically they are as they're moving through they're pushing and kind of building up this wall of air in front of them which decreases their efficiency in addition this wall of air that they're kind of pushing ahead of them when they reach something like a tunnel that wall of air hits the opening no tunnel and it creates a huge explosive noise as that wall of air kind
of impacts that opening of the tunnel and as a result of this it does a lot of structural damages to those tunnels so in order to kind of get an idea of how we could engineer these trains in order to slip through the air more efficiently they actually started studying different animal models one of them being kingfishers and the fact that the beak of a Kingfisher is developed in order for them to kind of as they die from great heights to kind of slip through that like the boundary layer of that
water extremely easily without causing any kind of damage any kind of physical damage to their bodies and that their beak is designed very specifically where it's very kind of small and pointy at the end and then gets larger as you move up towards their face to kind of help slip in to that water more efficiently so as a result we've kind of modelled the noses of these new Kingfisher which is what they're called it rains to kind of resemble that structure on these birds and as a result of this we
've created these bullet trains now that are 10% faster they consume about 15 percent less energy because they're not pushing this wall of air in front of them and we've completely eliminated the issue of that tunnel boom that big noise and damaging any of these tunnels so super super cool I find this stuff I just find this stuff super neat and there's so many more examples out there so this is something you're super interested in check it out also check out the major we have here on campus I wo
uld love to know more about that maybe I'll have to look it up for you guys but definitely cool stuff okay so the next thing that we're gonna kind of move on now that we kind of understand why do we study animals why understanding their biology is so important to us and hopefully I've given you enough examples that you're kind of that I'm justified it and that you're and that you're excited about it so basically where I want to start is what makes an animal an animal and this is a much harder qu
estion than you think and coming up kind of with a firm definition can be tricky because animals are so diverse that ultimately they're most likely is going to be some kind of exception to nearly every given characteristic that you can come up with so with that being said scientists have kind of can't come up with these five different features that have helped us to kind of broadly care characterize what an animal is and these five structures include cell structure modes of nutrients movement ge
nomes and reproductive production and development and we're going to talk a little bit about and give some examples of each one of these okay so the first one being cell structure so all animals Stav are multicellular so they are multicellular and they have cells that lack cell walls so this is different than the other organisms that we've talked about so far so bacteria fungus plants which all have cell walls that are made out of different materials bacteria being those peptidoglycan even archa
ea which also have a cell wall that are made out of those pseudo peptidoglycan fungus which are chitin and then plants which are cellulose so this lack of cell wall however allows more flexibility and movement in these animals therefore without these cell walls to kind of help give them structure we there needs to be some other kind of structural support system and for these cells and in animals this kind of extra or this cellular support system is known as the extracellular matrix and what this
is is this is basically kind of a network of material that is secreted from cells and it kind of forms this complex mesh work outside of the plasma membrane and this structure this extracellular matrix provides structure to help support and organize cells and some of these cells can be completely embedded within the extracellular matrix like you see here so if they these are this kind of network is all that extracellular matrix you can have some cells that are embedded within that and extracell
ular matrix and then you can have other cells that are kind of attached to the extracellular matrix on one side here and basically what this is made up of is that it can be made up of larger protein fibers such as collagen so that's kind of like what these structures here represent as well as different polysaccharides which you can see here that kind of create an interlocking Network and kind of help resist compression and kind of give the extracellular matrix this gel like characteristic and it
s role really is to do things like provide strength so it's tough it's kind of like the tough stuff that prevents our skin from tearing or the cartilage in our joints from compressing and kind of rubbing against each other in addition to providing strength it provides structural support so things like our bones are made up of primarily extracellular matrix which bones provide a support structure for our entire bodies and facilitate movement by giving our muscles places to attach to it helps in o
rganization so it plays a key role in kind of properly arranging cells throughout our body and kind of binding these different parts of our body together so for example kind of binding tendons to bones and it also plays a role in cell signaling kind of helping deliver molecular messages through different parts of our bodies okay so the next kind of defining characteristic of an animal is how they feed so their mode of nutrients so we know that animals are our heterotrophic so they can't produce
their own food and they have to obtain it from their environment and more specifically they are going to ingest other organisms or products of organisms in order to survive and there's lots of different modes of feeding one of them being you can have suspension feeders so these are organisms that are going to kind of filter out food from the surrounding environment kind of like these barnacles here that will filter out phytoplankton from the water surrounding them you can have bulk feeders they'
re gonna eat large pieces of meat at a time like these lions and you can have fluid flavors so things like this hummingbird that are gonna suck up plant SAP or you can have other fluid feeders like mosquitoes they're gonna feed on animal fluids like blood the next kind of characteristic is that all animals are capable of some type of directed movement and this process is supported by well-developed muscle and nervous tissue which is unique to animals no other group kind of organisms have muscle
and nervous tissue like animals do and as a result of these well-developed tissues it allows them to produce coordinated movement that allows them to perform specific tasks like acquire food or evade predators okay the next kind of a big distinguishing feature of animals are different genetic features so one that we have talked about before are these hawk genes where all animals kind of have these hawk genes and again these are sort of hawk genes are kind of sort of developmental master switches
so they're gonna control proteins that kind of direct the formation of particular body segments so if we think about it each Hawk gene kind of controls a hierarchy so it controls a whole bunch of other regulatory genes that regulate the expression of genes that kind of encode for proteins that then affect morphological development in a section of an organism's body so let's take this image here so you have a hawk a cluster of hawk genes right here select this dark-brown section this is going to
kind of control a whole series of regulatory genes that are going to dictate the expression of proteins that are going to cause the morphological development of this anterior section of this fly embryo to develop into a head whereas in this series are this kind of grouping of hoc genes is going to control whole series of regulatory genes that is going to develop the abdominal this kind of lower abdominal section in this fly here and we talked about that if you have a greater number of hoc genes
so these more master switches that you have you can develop more complex body patterns and shapes shapes so sponges only have one hoc gene have very simple body plans where things like mammals have I think it's 36 different hoc genes and as a result have much more complex and diverse body body plans another kind of unique feature of animals is that we have all kind of shared similar genes that encode our ribosomes so with animals if we look at the structure of their ribosomes the animals are th
eir ribosomes are made up of a 40's and a 60s subunit whereas in prokaryotes are made up of a 50s and a 30s subunit long guys one second my computer was gonna die it's gonna be bad okay so the other kind of unique genetic feature is if we look at the molecular makeup of our ribosomes our ribosomal RNA and the fact that eukaryotic ribosomes are made up of a 40s and a 60s subunit whereas in the prokaryotes are made up of a 50s and a 30s subunit and one of the kind of unique things about this is gi
ven the fact that the genetic sequence that make up these are RNAs in our ribosomes have been established at a very early stage in our evolution we can kind of use these sequences as a molecular clock which is what we talked about early in the semester where we can look at neutral mutations within these highly conserved areas and we can kind of determine evolutionary relationships between organisms okay the last kind of characteristic is how or or how animals reproduce and develop so all animals
had a similar reproductive mechanism virtually all animals are going to reproduce sexually where you have a small mobile sperm that's going to unite with a larger egg to form a zygote or a fertilized egg and how this process of fertilization takes place can vary so in some organisms it can be internal fertilization which is very common in most terrestrial organisms in other cases you can have external fertilization which is something that we see a lot in aquatic organisms where you have broadca
st spawners like these oysters here where they are gonna release their sperm and eggs into the water and they're gonna kind of mix around and fertilization is going to occur externally in addition another unique feature of animals is that all we go through a very struck shirred series of developmental stages where development is kind of defined as a series of changes in the state of an organism whether it's cellular or tissue or organs or at the organismal level that kind of results in an organi
sm at the end with a defined set of characteristics and sometimes there are very kind of unique developmental phenomenon one of them kind of being metamorphosis so this is where you have like in butterflies or other insects where organisms change from a juvenile to an adult and we're going to talk a little bit more about metamorph metamorphosis and how these work kind of later in our unit okay so how do we we're gonna start off with just how do we classify these organisms so all animals are with
in the domain Eukarya and they have a merge kind of from a super grip which is known as the opus codon days and they are kind of organized into a monophyletic Kingdom known as an Amelia and this monophyletic Kingdom the reason why this is a monophyletic Kingdom is the fact that all individuals in this and Amelia have kind of evolved from a single common ancestor and today we kind of recognize 35 different phyla within this kingdom of Animalia and for our unit on this in our class we are going to
kind of talk about and focus in on 13 of the most important recognized file as we talk about different invertebrates and vertebrate evolution so for much of our discussion we are going to explore kind of the major features of animal body plans and how they've changed as animals got more and more complex so that is where I'm going to end lecture today and next time we meet on Monday we're gonna start talking about some of the driving forces for what has caused animals to evolve and then start ta
lking about some of the specific body plans that biologists have used to kind of help classify these different phyla of organisms starting off with the invertebrates okay everybody have a wonderful weekend and have a great Easter and I'll see you all on Monday bye
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