hello bisque 132 this is the beginning of recorded lecture 3 2. uh continuing on with this this sort of intro to animal diversity chapter before we get into specific groups of of animals and what we're doing here is talking about the history of the entire planet uh as it pertains to living things and uh man these these figures make it look a lot well i i almost said a lot more complicated than it actually is but no it really is this complicated this is making it uh more complicated than i am going to put it so we're not going to be memorizing you know millions of years ago time periods and all the aeons eras periods and epochs and stuff like that this is kind of just to show you just how much is going on here what i'm going to do is try to provide a summary just hitting the the high points of things but yeah there's definitely a lot more to this i'm really just just scraping the surface here so this begins uh in the pre-cambrian period in something called the ediacaran period with the emergence of what's called the ediacaran biota the this this is where we see in the fossil record the first evidence of robust animal diversity lots and lots of different animals different shapes and sizes and these these things are weird right i mean this this looks more like a plant than an animal and and who knows what this thing looks like uh here's another um you know artists rendition based on the fossils we have trying to guess what these things could have looked like and again i'm bringing this up because these are so weird and it illustrates a point that as we go through this a lot of the animals we're going to see have descendants that are alive today and you can sort of see oh yeah that kind of looks like a bird that we see today or something like that uh but what's cool or interesting about these ediacaran biota is that they have no surviving members or descendants they're sort of just a dead end evolutionarily and that definitely can happen in uh in evolutionary history so my summary of this uh ediacaran period where we have the first evidence of robust animal diversity uh all this stuff is marine so we're i'll let you know when we make it to the land but right now all animal life is just in in the oceans and yeah no surviving members or descendants of these really weird just alien looking animals so this is this is where things you know started to get going but things really start getting big in the cambrian period so this time period is sometimes called the cambrian explosion we have a huge diversity of different animals occupying a lot of different ecological niches so instead of just you know being mostly uh cecil and not very uh dynamic here we have large dynamic predators here the anomalocaris and the uh opabinia weird looking they still look kind of alien uh but these things do look you know more more familiar than some of the stuff before these looks kind of like these look kind of like insects these these trilobites so uh none of this stuff is alive today but unlike the ediacaran biota they have left descendants so what we see emerging here is the ancestors to modern invertebrates and again we're all still in the ocean by summary of this so cambrian period here next highlight cambrian explosion a rapid geologically speaking rapid uh diversification of animals all invertebrates we haven't gotten vertebrates yet uh all marine as i said no surviving members but we see the emergence of the ancestors to most modern groups of invertebrates in this time period now a good question might be why like what what led to this why why did all of these new species emerge around this time period and there are a couple of explanations so this explosion might have occurred due to increased atmospheric o2 i mean we're animals we're heterotrophs we do cellular respiration we need o2 more more o2 in the atmosphere it's it's going to fuel the power of life of animal life a protective ozone layer sort of goes along with this it's easier to survive especially in shallow water if you've got an ozone layer and or increased calcium in the ocean due to geological activity so a lot of these uh a lot of these animals have shells uh made of calcium or that incorporate calcium extra calcium in the ocean you know would allow them to survive and reproduce better so the rest of the paleozoic era just not getting really skimming over a lot of stuff here uh did see the evolution of land plants so here's our next big thing plants took to the land before uh before animals did and you know i discussed this in our plants chapter when we talked about these early land plants uh you know more sunlight out here fewer predators at least at first and so yeah land plants throughout the rest of the paleozoic era uh we after that you know still within this paleozoic era because again i'm not breaking this down as as fine as you know one could uh after land plants we do see land animals now that there's food available on land that's an incentive for animals first invertebrates to colonize the land uh and so yeah the the ancestors of of modern spiders and centipedes were sort of first here um we also see uh marine vertebrates so the first uh fish uh basically you know weird looking shapes here but these are aquatic vertebrates within this uh paleozoic era and then eventually you can probably guess what's coming next land vertebrates and so uh in in this period near the end of the paleozoic the permian period we see land vertebrates that that look like this um and these are kind of weird looking i mean i guess uh these the dimetrodon is is something that a lot of people are probably somewhat familiar with this but this most chops and all this other stuff um these are not these are not dinosaurs uh despite and you know despite some of them superficially looking like dinosaurs uh most of these are what you would call proto mammals uh we'll get into this uh when we when we talk about mammals uh but these are actually a group of vertebrates that's more closely related to us than they are to reptiles so i know that the dimetrodon uh is you know sometimes shown alongside dinosaurs or you know in a book about dinosaurs or something like that for kids it's not a dinosaur even though it kind of looks like one it's more closely related to a mammal than a dinosaur and one of the reasons why these things are not as popular as dinosaurs just in you know the common um you know public consciousness uh they're not as well understood because remember we're not two dinosaurs yet this is an older time period we have fewer fossils of these things these are these permian land vertebrates and so yeah they're just not as well known as the dinosaurs and obviously these were not to last because we don't see any of this stuff alive today at the end of the permian period we have an extinction event not just an extinction event but a really really big extinction event uh probably the biggest extinction event of animals uh in the entire earth's history this is you know r.i.p to all of this stuff all these proto-mammals uh you know r.i.p to uh to these trilobites which had been around for a very long time since the cambrian explosion they all went extinct during this period as well um this so-called permian triassic extinction event uh led to the extinction of many animal species we're talking 81 of marine species and 70 of terrestrial vertebrate species so that's a that's a huge loss of all sorts of groups including including insects which are pretty robust throughout the planet's history but yeah this is this is sometimes called the great the great dying uh because yes this was a and a huge extinction event um yeah vertebrate and invertebrate aquatic and terrestrial just male a lot of stuff wiped out uh and you know there are questions as to why this happened um potential causes include one or more meteor impacts uh massive volcanic eruptions uh you know climate change brought out by release of underwater methane uh yeah again these are all possible or maybe all of these together this extinction event the causes of this are not as well understood because again this is a really long time ago hard to to try to track down but we know that all this stuff disappears from the fossil record now with all of this stuff gone or you know so many species gone what that leaves is empty ecological niches you know these large predator large herbivore niches with these things gone there's a there's a vacuum and the survivors are gonna fill that vacuum and you know who survived the permian triassic extinction event the ancestors to dinosaurs and reptiles so with the the playing field wiped clear of all these these proto mammals and gorgonopsids and stuff like that uh reptiles diversified exploded occupied all these different niches uh land land herbivores uh you know large land carnivores you know reptiles took to the skies took to the oceans uh this is in now the mesozoic era dinosaurs and other reptiles rose to dominance you know filling in these niches uh that were that were left empty after that great dying permian triassic extinction event and um i say dinosaurs and reptiles so i i want to you know i hope i'm not being pedantic here but you know these things uh like the dimetrodon sometimes like called dinosaurs but no these things are technically marine reptiles and this is a flying reptile the pterosaurs they lived alongside the dinosaurs and they were also reptiles uh but these are these are not dinosaurs but they were very successful flying uh and marine reptiles at this point uh so also in the mesozoic era so we saw you know dinosaurs and reptiles you know taken over the world uh but we also saw within this era birds and mammals so at this point mammals were mostly small nocturnal insectivorous you know not as dominant as dinosaurs were and birds very similarly uh you know not you know occupying these huge niches in the land the air and the sea both of these are just sort of in the background uh near the end of this era but they they did evolve um among the dinosaurs but as we all know this was uh this was not to last uh for the reign of the dinosaurs here we have another major extinction event the cretaceous paleogene extinction event this one's a lot better understood than the permian triassic extinction event this was caused by a meteor impact the evidence of which is still seen in southeast mexico uh and this killed off all the non-avian dinosaurs uh all of these uh successful flying reptiles large marine reptiles uh ammonites which were very common in the ocean the type of invertebrate closely related to uh to the nautilus uh all this stuff was wiped out so all the non-avian dinosaurs uh okay side note when we talk about birds and we look at some phylogenetic trees birds evolved from a specific group of dinosaurs and if you're talking about things in terms of clades a clade is an ancestor in all its descendants so technically birds are dinosaurs um anyway more on that later but uh when i say it wiped out all that i can't say it wiped out all the dinosaurs because birds survived this extinction event but all the non-avian dinosaurs were wiped out uh those pterosaurs those flying reptiles the large marine reptiles and ammonites all these things wiped out by the cretaceous paleogene extinction event and you know the story repeats itself with the the playing field wiped clear uh so many ecological niches are now empty guess who comes in to scoop things up birds and mammals so that leaves us uh in the current era the cenozoic era where we have you know large herbivore mammals and carnivore mammals in the in the ocean and you know birds in the sky you know these things really took over after the dinosaurs uh and you know all these other things from the cretaceous period were wiped out so hopefully you're seeing a pattern here and i only covered a couple of extinction events uh there have been others there's an end triassic one a couple of other ones going back further here that the pattern we see in the planet's history is you know a group becomes successful or several groups become successful you have an extinction event due to you know various causes when the ecological niches are emptied out new things will you know radiate outwards because of evolution selective pressure fill those niches and become successful there so here's the here's the takeaway message from talking about these mass extinctions mass extinction events lead to empty ecological niches which are filled by evolutionary radiation of the surviving groups so that's how we have the the world we have today uh the ancestors to all the the successful birds and mammals we see in uh terrestrial and aquatic environments were able to to get to those places because of the extinction of the stuff that was in those niches beforehand okay so again hopefully this was you know just a quick uh rundown of things because it definitely gets more complicated than the way i put it but i hope that that was an effective summary of history of life on the planet so now we're ready to actually start talking about animals and this textbook like many textbooks uh is going to split animals up into two chapters a chapter on invertebrates and a chapter on vertebrates so let's get started now with invertebrates so first off let me just clarify some terminology here uh when we're talking about animals in in general we're talking about members of kingdom animalia so members of kingdom animalia are animals and another name for animals is metazoans so metazoa animals kingdom and animalia that's all the same stuff okay here is the phylogenetic tree for uh metazoans for animals and man this is looking big and complicated but i'm gonna i'm gonna simplify this just just a little bit so um i'm gonna get rid of these uh these so-called tenefora comb jellies they look a lot like sea jellies or jellyfish you know superficially they're technically you know their own uh their own group separated from the rest of jellyfish but it's a relatively small group bam they're gone um but the placozoa is another group that doesn't have uh very many members they can be confusing compared to other groups with similar names they're microscopic marine planktonic animals uh it's not clear where they fit in but again they're not very big uh and they're not very understood so bam they're out of here um next let's get rid of aceola these are flatworms there is another group also called flatworms so uh sorry uh aceola you're out of here next let's go to ectoprocta and brachiopoda um they're you know pretty cool looking but they're two relatively small groups that especially in an intro course in the you know the interest of time getting rid of them and as simplified as i've made this i actually do want to add one group in nemertea also known as ribbon worms trust me when we get to them they're going to be worth adding in so hopefully this is where we're left now and hopefully this is a bit simpler than it was when we started it's still a lot of groups but again this is going to span several several lecture periods and yeah this is this is going to be our sort of road map to the next several lectures so just like we did with plants let's start simple and get more complicated uh let's start down here in a group called parazola so technically perizoa is a sub kingdom so this is uh you know domain kingdom phylum we're not to the phylum level yet this is underneath kingdom animalia sub kingdom parasola uh members of sub kingdom perizoa do not have tissues again these are the simplest animals that means they have so no cell layers so that means are they diploblasts or triple blasts neither n a not applicable are they acylimates or pseudo c n a not applicable are they protostomes or deuterostomes nope neither of those things so this is another sort of organizational chart thing it seems like an immense amount of information but you know this is just to organize stuff we're going to fill this out one thing at a time as we go through these different groups our first group within this sub-kingdom perizoa is going to be as we'll see in just a second and man it's dead simple to fill this one out uh as i said as perizones uh members of this group are n a for all of this stuff so that's that's an easy start to to this information so okay let's talk about uh peripheral so now we are at the phylum level this is you know the phylum periphera it's the only phylum within this sub kingdom of parazola and peripheral members of periphera are more commonly known as sponges so they come in all different shapes and colors and sizes but we're familiar with sponges i hope these are the oldest surviving group of animals and we've brought them up before and you know how simple they are in their evolutionary relationship to these colonial protists um sponges lack body symmetry so i guess these are going to be the exceptions to a lot of stuff i set up in the last chapter so they they are the you know example of having no symmetry at all uh many of these are irregular cylinders with a with a central cavity so this is going to be they come in all shapes and sizes this is going to be a common thing there's a central hollow cavity in here with one or more mouth-like openings but again no symmetry to the overall body now despite the you know sort of disorganization that you might infer from its lack of symmetry many sponges uh have a lot of specialized cell types so here we're gonna zoom in on things a bit here's your generic looking sponge with the central cavity and the opening at the top and yeah there are a lot of different cells uh going on here that do a lot of different things so members uh these are members of uh sub kingdom parazola that means they don't have tissues they don't have groups of cells that work together but they definitely do have cells with specialized functions so just try to make a point of that they don't have tissues but they definitely have specialized cells so you know whether it's you know cells that are involved in structural integrity or delivering nutrients or you know sexual reproduction or all these other things lots of different cell types in sponges so let's look at this let's look at the life cycle real quick so uh the life cycle begins when an adult sponge releases sperm cells with flagella uh these are gonna travel through the water column doing a little bit of swimming until they find another sponge as a side note most sponges are hermaphroditic so they have they can make eggs and sperm from a genetics evolutionary standpoint it's usually best to not fertilize your own eggs you want to spread your genetic information around a bit so despite being hermaphroditic a lot of sponges have a sort of cycle where they'll go through a cycle where they make sperm but not eggs and then switch and make eggs but not sperm to avoid fertilizing themselves but anyway sperm gets to egg you have you know fertilization the formation of a zygote all that cell division the larvae is released into the water uh and it you know kind of swims around a little bit it has flagella this kind of shows it sorry it's the best figure i could show from this is when scientists get to draw things they're not always the best but this is probably better than what i could draw i just want to show that the the flagella coming off of this sponge uh larva uh to show that these things unlike the adult form which just is anchored somewhere and doesn't move at a certain point in their life cycle they do swim around a bit until they anchor themselves and and into uh into the ground uh grow more and become sessile filter feeders so okay what's my summary of this uh sponge life cycle adult releases sperm sperm gets to another sponge and fertilizes its egg again hermaphroditic uh if you needed a ketones definition for this hermaphroditic refers to an animal where both male and female gonads are present in the same individual a larva develops larva released it has flagella it is motile the larva settles down grows into adult it is sessile and a filter feeder okay so i believe this is the first time i've used this term although i'm going to use it a lot in this and next chapter a filter feeder is defined in the key terms as an animal that feeds by straining suspended matter and food particles from the water so just yeah we're going to see a lot of different animals that have this this basic lifestyle of getting their food by straining it from the water now how do they how do they do this well the way they strain stuff from the water is definitely not passive uh these sponges don't look like they're doing anything just by you know staring at them but a lot is going on if you look more closely inside of the sponge body are these coanocyte cells uh these collared cells with flagella and even though a flagellum is small by having many many many many many many many many of these uh all beating their flagella back and forth this creates a water current it's going to pull water in from the outside through these pores called ostia and inside of this central cavity called the sponge a seal this is not a celium this is not a pseudocellulum it's just seal means cavity and so that's why we see this as part of the term but this is not a coelom in any way it's just a different type of cavity anyway where particles and stuff are sent into this sponge acetyl cavity and then out through this uh this oscillator sort of mouth at the top here so as this water flows through that's how these coanocytes are able to capture food particles so again just looking at a sponge under the water it's not moving it doesn't look like it's doing much but on a microscopic level there's a lot of movement going on in these cells there's a lot of water movement going on to to do a really great job of filtering the water around them so here's my summary of that sponge feeding these cholinocyte cells use flagella to create water current through the pores in the body called the ostia these cells also capture food particles from the water the water enters this central chamber the spongy seal and is propelled through a large opening out of the sponge called the oscar now let's talk about structure a little bit we're going to talk about skeletons and in most of the the things that most of the animals that we go through in this and the next chapter uh the sponge body and you know some of these can grow to be kind of tall has to have some sort of structural support uh and they're going to get this through a network of protein called very creatively a protein called spongin uh and or uh these these spicules uh made of silica or calcium carbonate so some sponges just have this sponge in they're the soft ones that you would you know wash yourself with but some of them have sponge in as well as these spicules which you definitely would not want to rub this on your body uh but but it gives them an extra layer of structural support and discourages things from eating them so the sponge body is supported by proteins and or spikes of silica slash calcium carbonate secreted by specialized cells so yeah more of these specialized cells here that are involved in building this uh quote-unquote skeleton so let's talk about reproduction a bit i mean we saw in the the life cycle the sexual reproduction you know sperm plus egg all that fun stuff sponges are also capable of asexual reproduction in a couple of different ways some of them can just bud off another fragment which can detach and then attach to the ground and then just be another individual that's a clone of the parent or they can reproduce asexually through fragmentation where you know maybe an attack by a predator or you know a storm or something like that some fragments can be torn from the adult body they can float off attach themselves and develop into a new individual so either either of these things won't work sponges can reproduce asexually by budding or by fragmentation okay so that was a lot on sponges but that's all i have for them let's let's move along here so we're done with peripheral and we're done with this perizon the sub kingdom perizoa no tissues the only member there was periphera so everything else you know all of this stuff every other group that we talk about is going to fall under the umbrella of eu metazoa this is another sub kingdom members of sub kingdom eu metazoa actually have tissues they have groups of cells that work together and you know like we saw visually this sub-kingdom is going to include all further groups so okay which one of these further groups are we going to hit up next well let's start down here with a group called nigeria so members of phylum nigeria are called cnidarians and they include uh sea jellies also known as jellyfish um there's uh an interesting movement in the marine biology world to not call these things jellyfish anymore which i get they're they're not fish like why should they they're very very distantly related from from actual fish uh why do they have fish in the name and so they're trying to be rebranded as sea jellies instead of jellyfish same thing is true for um starfish and sea stars but anyway however you want it sea jellies also known as jellyfish corals stoney or soft and sea anemones these are all what we call nigerians so what can we say about cnidarians well these are examples of what we we defined in the last sort of intro to animals chapter diploblastic so that means you have an ectoderm and endoderm and then a non-living layer uh in the middle so that means uh that means they're they are neither of these to go to this remember the celamate and pseudocylinate and acelamate this these were subcategories of triploblastic animals so they're diploblastic and you know they don't have a body cavity they're not acelamates because you know this only applies to having three layers and no additional body cavity um so yeah no body cavity uh these are only found in triploblastic animals um the non-living layer in between the endoderm and the ectoderm is a jelly-like mesoglia where they get the fish or sea jellies get their name uh that's between the mesoderm uh or i'm sorry between the ectoderm and the endoderm so that helps us fill this table out a little bit diploblastic n a for body cavity uh symmetry they got radial symmetry again here's a coral that was our you know poster child example for radial symmetry body plan so members have radial symmetry uh and no circulatory system so we'll we'll get to circulatory systems they're going to be two major types we'll get to that eventually but this is still sort of an n a uh for the circulatory system cydarians are not going to have um complex body systems at all so it's an it's an anime uh from circulatory system oh and protostome or deuterostome that's what i mean by the the embryonic development that's also an n a this is something that's only going to apply once we get to triploblastic animals so again this this table is going to seem very intimidating once it's all filled out but we're doing it one group at a time and a lot of this stuff is easy enough uh to remember a lot of the early ones are just going to be n a when we talk about these things so all right what can we say about cnidarians well as i mentioned a second ago uh these they do have tissues so they're an upgrade from you know the the parazola but there are no advanced organs or organ systems they have what's called an incomplete digestive system that means they are not tube shaped animals with a mouth and an anus there is really no mouth or anus there's just a single opening to the gastrovascular cavity and we can see this sort of cartoon of a of a sea jelly cartoon of an anemone they're basically the same thing just flipped upside down you have a single opening a gastrovascular cavity and an exit there's no tube there's no mouth there's no anus gas exchange we're going to discuss this in several most of the groups we talk about there are no gills or lungs gas exchange is just done directly from the cells to the surrounding water or the water within that gastrovascular cavity so by being you know relatively thin and having a thin you know skin uh they don't need lungs or a respiratory system or gills they can just do gas exchange directly from the cells to the gases that are in the surrounding water um they do have nerve cells to in a coordinated fashion grab something and bring it to the the gastrovascular cavity to eat something but there's no brain again there's no complex organ system so there's definitely no brain uh in cydarians this mesoglia which we've been seeing here so this is the jelly-like substance in between the endoderm and the ectoderm it performs the function of a digestive system and a circulatory system again there is no organ system there are no no real organ systems here but i mean the function of a digestive system is to you know break stuff down and the the function of a circulatory system is to move nutrients and gases around this jelly does both of those jobs you know stuff breaks down here and because it you know runs the length of the entire body it effectively moves things around even though it's not actually circulating the way a more complicated circulatory system would do so the the mesoglia the jelly fulfills the function of these systems now as we've been seeing there are two possible body plans here uh the medusa and the polyp uh the polyp is cecil uh the medusa is motile uh and some cnidarians actually do both so a lot of sea jellies are you know the medusa body plan that's you know easy to see uh corals and stuff for the body plan some nidarians go back and forth uh so some seed jellies will have a certain phase of their life where they have the medusa body plan uh but then you know uh you go back to the body plan and convert to medusa again so that is called dimorphic not all of them do it some nigerians are dimorphic they alternate between the polyp and the medusa just as a normal part of their life cycle now uh most not all cnidarians are predators in one way or another and they use these unique specialized cells called nidocytes a lot of silences here but these specialized cells called nidocytes that are equipped with organelles called pneumatocysts they have a touch sensitive things sticking out when they come into contact with something that will cause the ejection of this barb and thread often delivering paralyzing venom again all this is at the cell level it's microscopic but you know the venom is powerful enough to paralyze uh this prey bring it into their gastrovascular cavity and and then digest it so i'm saying most because they're definitely exceptions most cyderians are predators using specialized cells called nidocytes with organelles called pneumatocysts to deliver paralyzing toxins so okay now this this phylum is robust enough to where we can look at specific groups within this phylum and if you remember the the first day of class the domain kingdom phylum class classes their next level of taxonomy so we're in phylum nigeria let's talk about class anthozoa class amphizoa includes sea anemones and corals so these are uh amphizoans they have uh polymer bodies only so none of these amphizoans swim around in the medusa form and uh some interesting things about them some have symbiotic relationships uh with dinoflagellate algae hey this might look familiar to you when we talked about dinoflagellate algae i used this exact slide but here it is again so uh the now we're talking about the the coral or the amphizoan you know half of this thing uh you know providing a safe space for these uh these protists dinoflagellate algae and the the dinoflagellates you know performing photosynthesis and uh giving uh sugars photosynthesis products to their uh protector slash captor don't worry about it so some have a symbiotic relationship with dinoflagellate algae and this is vital in the formation of coral reef ecosystems so this is not just a member of the coral reef but it's a vital foundational part of the coral reef ecosystem uh if the coral dies uh and it's a lot of coral species are exquisitely sensitive to changes in ocean temperature or ph or pollutants uh if the coral dies it bleaches it turns white and man most of the fish go with it most of the other marine invertebrates and vertebrates and mollusks and all the other stuff goes with it this is this is a bleach tricked in coral reef uh so coral is is not just you know part of the ecosystem it is the ecosystem in many ways uh and so yeah these are anthozoans uh vital in the formation of coral reef ecosystems all right so that's all i got for the classic and when we get to the class level usually i don't have much that i that i want to say about members of a class we got to keep moving on so the next class i want to bring up is class uh scifizoa these are jellyfish aka c jellies and we kind of discussed these already here's a sea jelly uh that you know we typically think of them as having the medusa body plan but as i just said some of them go back and forth and are dimorphic um i don't have anything else to say about schifozoa you should just associate schiffozoa with sea jellies they can have the medusa or or be dimorphic i have two more classes uh to talk about but uh as awkward as this is this is typically where i run out of time in the in-person lecture so it's it's an awkward cutoff but it is what it is uh we'll finish up the last two classes of nigeria and continue on with invertebrates in the next recorded lecture