hello bisque 132 this is the beginning of recorded lecture three three uh still in the middle of our invertebrates chapter this is a long one and so last time i had started talking about phylum cydaria and we were getting into the class level we did two of them we got two left so let's pick up where we left off next we have class cubizoa uh this is a jellyfish which might be a little confusing we already did those right class schifozoa was supposed to be sea jellies or jellyfish well technically these are called box jellyfish and uh despite their superficial resemblance to other sea jellies genetically these are a distinct group and there are some physiological differences as well the cube might be a little confusing this doesn't look very cube like to me but there are four distinct you know two in the front and two in the back uh uh pentacles places where tentacles uh emerge so you know four quarters i guess that kind of looks like a box not not to me but i mean that's where it gets its name these four points there kind of look like a cube or a box hence their name box jellyfish uh and they're smaller uh than most sea jellies and schifozoa but they are much much more dangerous uh despite their size so a box jelly you know class cuba zoa again we're still in phylum nigeria class cuba zoa these are box jellyfish box or cube shaped medusa smaller than most sea jellies but more dangerous and one other weird thing to point out that point out about them they have eyes and this is really weird to think about and these are definitely not you know complex eyes like we see in in other animals but these are simple light sensing organs but yeah they have light sensing organs very strange and they they have these other jellies the scifizones do not have these so uh eyes but as i mentioned before no brain so no way to really process complex information just simple light sensing here in these cubisons so okay last class here class hydrozoa this includes hydras nope not these guys although that is pretty cool looking we're talking about these guys okay i i guess i can kind of see the resemblance here uh these these arms these tentacles are not heads uh as you know someone imagined comparing this to the mythological hydra these are these are tentacles these you know uh bring food into this gastrovascular cavity this is of course an example of the polyp body plan here interestingly some hydras can be marine and some can be fresh water so this is the first time we've seen freshwater nigerians and i this might be the first time i've used these terms maybe i've thrown them out before but this is the first time i remembered to put them in the key terms if you needed to to know what these are marine means salt water reading from the key terms an organism that lives in high salt water of an ocean or sea and fresh water an organism that lives in the low salt water of the lake river etc so anyway i'll continue to use these terms throughout this in the next chapter uh yeah hydrous some are marines some are fresh water and you know i use this as sort of the prototypical hydra but they come in all sorts of of shapes and sizes and forms and organizations so this is a solitary polyp that's fresh water but sometimes these polyps can form big colonies so here's one that grows to you know a bunch of these polyps coming together as a colony if it wasn't confusing already this looks like a jellyfish or a sea jelly some members of hydrozoa like this peach blossom jellyfish have the medusa body plan and yeah this one's fresh water very strange and so this is our third jellyfish looking thing but it's in its own class of hydrozoa and perhaps most uh bizarre uh is the the portuguese manimour which also kind of looks like a sea jelly but if you look at this very closely i don't sweat the details here this is actually another one of those colonies it's a colony of polyps where individuals in different parts of the colony take on different roles to fulfill different functions you know making this you know fairly large you know macroscopic structure that looks like one individual looks like one organism but it's actually a motile it moves around a colony of polyps so yeah talking about hydrozoons they can be solitary polyps they can be solitary medusa or they can be large colonies of a bunch of individuals okay now that takes us to the end of cnidarians uh next before we move on to all of these there are some umbrella groups so here we go by left area we are now talking about uh animals with bilateral symmetry so all further groups have bilateral symmetry remember that means a single plane down the middle and our triploblastic so everything from here on out is going to have three cell layers so actually let's go to this table that's going to make this easy you just have to remember the two that are not triple blasted because everything else is triploblastic and for symmetry you just have to remember the two that are not bilateral everything else is bilateral so yes it seems like a ton of information but it's it's not going to be so bad uh so within this group uh we can see protostomes and deuterostomes here there's the clade of protostomia and here's the clade of deuterostomia uh we're gonna look at protostomia first and go to deuterostomia eventually so now we're talking about glade protostomia members are called protostomes and yeah that's going to include most uh everything uh everything except for chordates and ekinoderms are those are going to be our two deuterostomes so yeah we're i can't say all further groups are protostomes but most further groups for for quite a while are going to be part of this clade of protostomia and again i discussed in the previous chapter what it means to be a protostome so let's divide things down even further uh there are two clades within protostomia ecdysozola and lofotrochozoa let's do this lofotrochozoa clade first uh this is technically a super phylum uh so sorry for the uh the the messiness of all this just like i did for plants there is a document on moodle a word document that shows all the different clades and super phyla and sub kingdoms and all that fun stuff it doesn't have any new information that you need to know but if you are getting kind of lost in the sauce here with all these groups underneath other groups underneath other groups that might be a good document for for you to to check out just to clarify which groups are within other groups which are within other groups and stuff like that anyway we are inclu clade uh protostomia super phylum lofo trocozoa yes i have to pronounce it phonetically like that uh members uh have either a loaf a four uh which is a ciliated uh feeding apparatus uh or a trochophor which is uh this these two bands of uh of cilia around a central feeding structure uh two bands of cilia on their larvae so yeah low trocozolans uh either have a loafa four or a troga4 so that's where they get their incredibly long uh name from so okay we're in super phylum lofotrochozoa uh let's start with a group called platyhal menthis uh platyhelminthes are colloquially known as flatworms and yeah some of them are pretty dull looking uh some of them can come in very bright fun colors uh but yeah phylum platyhelminthes flat worms you could think i think i think plat and flat rhyme with each other so that's an easy word association here platyhelminthes flatworms if you may if you remember these are the the poster children for the acelamate body plan so remember everything from here on out is going to be in one of these three categories everything from here on out is triploblastic these ac these flat worms have the acelamate body uh cavity you know ectoderm mesoderm endoderm but nothing else no extra celium or pseudocolumn so that helps us fill this out acelamate here now what can we say about these worms well they're definitely an upgrade over nigerians because we're now looking at animals that have complex organs and organ systems so just looking at this cross section we can see eyes we can see a nervous system that runs the length of the body we can see intestine we can see a digestive system running the length of the body an excretory system going the length of the body here's another figure showing you know different parts of it there's the digestive system again there's the nervous system again there's the excretory system again and this one shows reproductive systems uh male and female these are hermaphroditic animals and so yeah this is definitely a level of complexity we didn't see in cydarians definitely didn't see in sponges so platyominthies have specialized complex organs and organ systems uh going through these uh a brain in a nervous system you know some of these groups have eyes that are more complicated than cydarian eyes to say that reproductive systems as i said most of these are hermaphroditic and have male and female in the same individual uh digestive system that runs the length of the body so this is this is an important detail here there are a couple of systems that are missing here if you try to complete compare their anatomy to to human anatomy and one of the systems that's missing uh is a circulatory system and the reason that is this is missing is because uh we have a circulatory system because we digest our stuff in a localized area and then our circulation spreads that throughout the body well because their gastrovascular cavity their digestive system runs the entire length of the body there's no need for a circulatory system to spread those nutrients out they're already being spread out so just as important as noting the systems they have is noting the systems they don't have and why they don't need them so the digestive system serves the function of a circulatory system as well they have an excretory system powered by these unique to this group so-called flame cells so this gets rid of waste again runs the entire length of the body and there's one of the flame cells sending waste out through this excretory pore another system that they are missing you know if you try to compare this to human anatomy and the human organ systems is a respiratory system uh you know lungs or gills or some way to do gas exchange they don't have one because they don't need one they can just breathe through their skin we're going to see this in other groups if you are really small or if you are really flat you don't need a way to move gases around you can just exchange gas with your surroundings so no respiratory system their flat body allows gas exchange simply via diffusion so this allows us to finish filling this out for platyhelminthes triploblastic acetylmates bilateral symmetry protostomes circulatory system here's another uh another n a they they you know fulfill that function with their digestive system so a lot of these are free living um like these just living around eating uh you know detritus pond scum or whatever in a pond a lake uh but there are a lot of parasitic members as well including gill flukes which are a fish parasite liver flukes which uh affect humans here's don't memorize this but i mean liver flukes have a significant impact on global human health and infecting uh they have a weird part of their life cycle within a snail and then infect fish and can infect humans tape worms are another example of a parasitic uh hill memphis flat worms so the tapeworm also has a fun life cycle going from humans to you know to other animals back to humans again cook your meat all the way through but yeah not getting bogged down and naming all these you you should just know that a lot of plenty help memphis are free living and a lot of members are parasitic as well okay that's all i've got for flatworms let's move on now to a group called rotifers or phylum rotifera so here's what a typical rotifer looks like under a microscope and you know a cartoon diagram showing the the basic body plan here uh these these are small these are microscopic animals uh they are aquatic they live in water uh and if you could see here there's the pseudo seal these are pseudocylinates they have this extra body cavity here in between the mesoderm and the endoderm so just organization still talking about protostomes this is still in that super phylum lofo trocozoa phylum rotifera microscopic aquatic pseudocelimates so this is the first time we've seen uh this type of body cavity this pseudocoelum why what does it do well in this particular group the pseudocelium is used as a hydrostatic skeleton we can kind of see this here this this cavity this pseudo seal filled with pressurized fluid so this is the first time we've seen this but this is definitely not the last time we will see this a hydrostatic skeleton is used in several groups later in this chapter this is where pressurized fluid is used as the actual skeleton instead of instead of bone or or spicules of of calcium carbonate or something like that pressurized fluid uh it's not as strong as bone or cartilage but it serves as an effective attachment point for muscles so it fulfills that function of the skeleton so that's what the pseudocolumn is being used for that allows us to fill this out pseudocylinates and it's still n a for the circulatory system because they're salt so small because they're microscopic they don't need a dedicated circulatory system so what else can we say about these rotifers well uh the way they feed uh they have a couple of unique things associated with their feeding one of these is the corona located near their mouth and this sort of whirls around when you see these in motion that's that's where they get their name rotifers these rotating animals the movement the wild movement of this corona sort of sucks in food particles into the mouth and hence the name rotifer rotating thing you know whatever the corona is that feeding structure and then past the mouth is this structure called the mastax which is basically like a job uh basically like teeth uh sort of grinds down food a little bit again this is all very small these are microscopic here's uh some very gnarly looking um microscope images of uh different mass tanks we see in different species of rotifers uh but yeah on a microscopic level it's grinding stuff down so each of these are defined in the key terms if you want a more formal definition the corona is defined reading from the key terms now a wheel like structure on the anterior that means the the front the head the mouth portion of the rotifer that contains cilia and moves food and water toward the mouth and then the mass tax a jawed pharynx unique to rotifers again sort of breaking things down so yeah they've got some pretty cool stuff going on uh despite being microscopic and that's that's all there is to them so uh not breaking it down uh further than that phylum level so next we've got this uh this group that i that i added that i felt necessary to to insert into this uh phylogenetic tree supplied by the textbook so we're still protostomia we're still super phylum lophotrocozoa phylum nemertea these are also known as ribbon worms or proboscis worms and uh you know they're not much to look at this looks like a pile of guts on the the ocean floor and here's one in a terrestrial environment looks like a pretty uh you know pretty normal generic looking wet worm uh and yeah these are called ribbon worms proboscis worms most are marines some are terrestrial i may have thrown this term out before but this is the first time i remember to highlight it for the key terms terrestrial means organism that lives primarily on land um they can be predators or or scavengers eating dead organic matter but the reason why i wanted to talk about these and these are not just your generic sort of earthworm uh is because of their proboscis this stuff so when they are threatened or when they are hunting they will invert this uh proboscis which is housed inside their body uh in order to grab something so this is a sticky structure that can web sort of wet out and entangle their prey or what they're trying to to trap or what they're trying to eat or what they're trying to fight off so here's sort of a boring cross section but it does show this proboscis sort of folded up within this cavity called the wrinkle seal uh and then it can be everted or ejected out um in a fashion like this uh so nemerteans have a proboscis housed in the wrinkle seal cavity that can be ejected turned inside out use used to capture prey basically these are celamates and their celium houses a closed circulatory system so this is the first time we've we've seen both of these things remember the coelom is a a body cavity within the mesoderm so it's different from the body cavity of a pseudocoelamate like we saw just a second ago and this house is a closed circulatory system so at this point i think i should bring up what a closed and what an open circulatory system is so a closed circulatory system is when blood is contained within specific blood vessels it's kept separate from from the organs from from the rest of the body it's within this sort of contained or closed off system and circulates around this is a different type of worm an earthworm that we're looking at in this image here but this should sound familiar because this is us vertebrates humans have closed circulatory systems as well a lot of different animals are going to have this type of circulatory system blood blood vessels closed off from everything else so in a closed circulatory system blood is contained within a heart or hearts you know depending on the animal we're talking about parenthetical s there uh and blood vessels since pump it is pumped throughout the body now uh at this point i think i may as well bring up the other type of circulatory system even though we haven't gotten to a member that has this yet the open circulatory system as opposed to the closed circulatory system where blood is contained within vessels in an open circulatory system the the fluid it's not called blood it's called hemolymph uh just it's sort of floating around in this body cavity and the organs are just sort of uh bathed and surrounded by this hemolymph fluid and you have a heart or hearts that will circulate this around so there is movement occurring but the the fluid that carries nutrients and gases and stuff is not closed off within vessels uh the the organs are just surrounded by it within this cavity so in an open circulatory system organs are surrounded by something called hemolymph not blood uh in a cavity called the hemoseal a heart or hearts uh circulate this hemolymph within the hemoseal so again we haven't gotten too uh in an animal with an open circulatory system yet but i wanted to introduce these uh these both here uh while we were at it so filling out this table here uh nemertea's selamate body plan with a closed circulatory system okay onward to mollusks and annelids starting with mollusks so this this is a pretty big one so this is clade clade protostomia super phylum lofatrokozoa phylum moluska i say this is a big one because there are quite a few members here this is sales this is slugs this is clams this is scallops this is squids and octopi and tusk shells and titans and cuttlefish there's a lot here this is a very large phylum most of these are marine you know meaning salt water uh but there are some fresh water members and fresh water snails for example and even some terrestrial members like slugs so phylum mollusca mostly marine some fresh water some terrestrial now it might be kind of difficult to imagine something that ties all of these things together you know what does what does a scallop have in common with a slug or or what does a squid have in common with uh with a snail well as it turns out there are two features uh that all mollusks do have in common even though they can be modified and in different ways within different members one of these morphological features is a structure called the foot so we're looking at a snail here but this is meant to be sort of a generic representative member of uh of phylum mollusca uh the foot is labeled down here so in a lot of mollusks this foot is used as an attachment point something something to attach to the ground and sort of crawl along this is a muscular structure used for moving around for for locomotion and or anchorage uh we're of course going to see this modified in things like cuttlefish and octopi and nautiluses the foot you know is modified to form all these tentacles and there is a foot inside of these shelled mollusks we'll see when we get to them so this is a structure that they all have morphological features of phylum mollusca a foot muscular used for locomotion and or anchorage the other structure that mollusks have in common is a structure called the mantle you can see it labeled here this is located on the dorsal surface although it covers the entire body uh this is a protective thick sheet of skin that may or may not secrete chemicals that form a shell so you know obviously some of these have shells some of these do not have shells but they all have this thick sheet of skin called the mantle so mantle is defined in the key terms as a specialized epidermis that encloses all visceral organs and secretes shells in members that have shells may or may not secrete calcium carbonate shell and what this mantle does uh the the existence of this structure creates a mantle cavity which houses uh gills and or lungs depending on whether it's aquatic or or terrestrial so there's the mantle uh and then here's the mantle cavity in here all right most so those are the two features that they all have in common uh most but not all mollusks mollusks have a structure called a radula used for feeding we can see it labeled here there's radula right there at the mouth uh to appreciate this a little bit better we probably need to zoom in a bit whoa there we go so there's the radula and man this thing looks like a buzz saw or something like that um is as scary as this is actually let's zoom in even further whoa really scary looking uh as terrifying uh as this structure looks uh it's incredibly small uh and it's used for scraping algae off of rocks most of the time so this is this is a structure uh used for feeding you can see it's sort of scraping food source off of something and bringing that uh into the mouth so most not all most uh mollusks have this radula for feeding the key terms to find this as a tongue-like organ with kittenous ornamentation that's a fun way to describe these horrible saw blade spikes kiteness ornamentation uh anyway what else can we say about mollusks uh these are selamates so that'll help us fill out that table in just a second uh however their celium is reduced so what we're going to see this again in another group they have just because you have this body cavity doesn't mean you have to do something important with it you don't have to do something you know vital with it they are celamates they have this celium cavity but it only houses the heart and the gonads and so yeah there's not it's not doing much with with this celium cavity uh and most mollusks have an open circulatory system so i defined this just a couple minutes ago this means no blood you got hemolymph instead and the organs sort of bathe in that so all right that allows us to fill this table out for mollusks they are celamates and circulatory system hey i said most have an open circulatory system so that's why i'm saying either or either closed uh or open now because mollusca is such a large phylum we have to at least briefly get into specific classes break things into the class level so let's start with class polyplacophora members of this class are called chitins it's spelled chaitons but but it's it's pronounced chitins kind of like the exoskeleton of a fungus or the uh cell wall of a fungus sorry if that's confusing anyway kitens um and yeah these are uh marine um mollusks that crawl around you can see the muscular foot there used for crawling around you can see the the mantle actually here's a sorry for the poor quality of this um there's the foot used for for crawling around for locomotion there's a radula present in the mouth here's the mantle uh and here's a shell you know secreting calcium carbonate to harden the the top of it uh yeah kind of typical mollusks in a lot of ways so these are called chitins they're all marine uh specifically eight plates make up that dorsal shell uh and these are mostly herbivores they're using that radula to scrape algae off of rocks so a pretty peaceful you know lifestyle here but um yeah these are polyplacaphora all right uh moving on again you know when we get things to the class level usually i'm pretty brief with things uh move on to class bivalvia so this is going to be our clams our oysters our mussels and and others these are of course uh aquatic and they are filter feeders so they do not have radula this is why i said most have radula but definitely they do not but if we look at a generic bi valve we can see the other structures here so there is a muscular foot they're not crawling around with this like a snail or a slug or a chitin would but members can use this foot to burrow themselves in the mud or the sand so that is used for moving around um and here you can see the the filter feeding strategy a siphon moving water in past the gills there's a mouth and you know a stomach intestine anus but the water flows through out through an excellent siphon and yeah that's uh that's filter feeding for you uh the mantle uh isn't really kind of labeled here and of course there's a shell secreted by the mantle and bi valves uh as well so um yeah filter feeders you know radula um we're we're now getting into animals that we're all pretty familiar with and probably seen or touched or eaten uh so when i when i get to groups like this in this chapter in the next chapter i try to say something interesting about them uh so in addition to this stuff that you probably already know about i want to point out that some species have sensory eye spots uh so here's a scallop with these eyes staring at you nowhere near as complex as that of vertebrate eyes but i mean they are light sensing organs they are eye spots kind of freaky looking okay uh moving along to class gastropoda so um means stomach foot yep snails and slugs and we're used to the ones that are uh that live in terrestrial environments but there are plenty of snails and slugs that live in aquatic environments both marine uh and fresh water so gastropoda these are snails and slugs uh obviously they may or may not have a shell you know snails having a shell slugs not having a shell aquatic and terrestrial members yep yep yep yep um and so yeah what can i say about them that's interesting that you maybe you haven't heard of before well an interesting thing about shelled members you know specifically snails during the development of their body plan they experience something called torsion so in a typical body plan back to this chitin hair you have a mouth at one end and you have an anus at the other end i mean that's that's how our bodies work uh as well it's a pretty typical way to have a tube shaped body however in the snail body plan things take a 180 turn you have a mouth at one end and the digestive tract there's the 180 and the anus points behind the head instead of pointing back opposite to the mouth the reason for this is not well understood it's it's not that maybe it has to do something with uh with having the shell fit correctly on the body but that you know there's some reasons why maybe that's not a good explanation for this but regardless what the reason for this might be this is definitely something true uh as shelled gastropods experience this torsion uh during during the early development of their body plan so uh still talking about gastropods shell members experience torsion during embryonic development this just means the anus points forward just behind the head so kind of weird for us to think about but that that's their body plan okay we have a few more classes to get through but this is typically where i run out of time in an in-person lecture so again sorry for these uh awkward cut-offs but it just is the way it is uh we'll pick things up and finish up mollusks in the next recorded lecture but this is the end of 3-3