hi everyone welcome to lecture six for bile 1263 living organisms to So today we're going to be looking at kindermat um and start off uh our first look at arthropoda okay so the phm fin deata are gones you remember we talked about protones and gones um they all live in Marine environments they all have a uh specialized water vascular system with tube feet pedicellaria um and they they have pent radial symmetry we're going to look at the different classes um including uh urchins KES C cucumbers starfish and brittle Stars well then move on to arthropods looking at how they have a jointed exoskeleton jointed appendages a hard cuticle including kiteen uh how it's has a fusion a they are segmented with Fusion of those segments known as tagmosis and how that can specialize different body regions and appendages they' got open circulation with a hemolymph moving through a hemo seal look at their different types of um eyes their digestive systems how they respire um through them um how the body surface is important in that uh arthropods have bilateral symmetry rather than radial symmetry um the um dorsal brain so uh brain and in the head region and how they grow with ecodis you may remember that that means molting of an external skelet so phm AATA are convergence with mollusks okay that's why we're starting them but I'm going through these immediately after mollusks from the last lecture okay they molis are protones whereas a kind of deat are butoon okay and convergent means they are evolutionarily convergent they are not closely related but they have evolved some very similar forms and functions including uh this kind of pent radial symmetry that you don't often see in jist Stones okay so they have um hard caleria including calcium shell otherwise known as a test made of small uh plates um and uh one of the um you'll remember that uh mollusks had this scraping radular mouth part well many echinoderms have scraping mouth Parts as well for feeding on algae for example this is known as Aristotle's Lantern okay and you can see from this tree kind of to Mar our part of the dter stones but they've gone from bilateral symmetry back to a form of radial symmetry at least in the adult these calcified plates okay the rest most of the rest of the kind uh or all the rest of the gones um exhibit mostly bilateral symmetry okay so this is a example of Aristotle Lan or the scraping uh speeding uh device at the bottom of urchin seen in cbia in Trinidad while ago the basic structure of the kind of damato as I said they've got pent radial limit so five different axes of symmetry such as you see in this starfish here or as otherwise known as a SE star okay in the sea star in each uh arm it has a full complement of organs that includes uh kind of digestive uh GL organs digestive glands uh gonads reproductive organs um the stomach is uh in the center of the animal they also have um as I mentioned this kind of hard test serious test um and a uh water vascular system okay that's shown in blue here okay so you have uh water going in through the uh madreporite through the system okay and then it will [Music] um change the uh pressure within uh this uh water vascular system to perform various different functions such as the movement of tube feet at the end of the r vascular system in the example of this sea star which can help with uh Locomotion and also feeding okay so here you have a transverse section of the arm showing your um your serious plate there's a seum so the celomic cavity uh these are cumate animals going now as digesting glands your tube tube feet as part of the M vascular system you'll see with from the lari that rather than having pent radial symmetry has bilateral symmetry like the rest of deter Stones okay and it moves through the water um the marine environment uh beating it cyia rather than using those tube feets as the adult sea stars do okay if you look in a little bit more detail at these Che feet you can see them at the end of an arm of a sea star okay so all all the time you've got water kind of being pumped into and out of this uh these Che feet okay so the pressure the water pressure can increase or decrease but also the CH feet have muscles uh which combine with this kind of change in press in uh hydrostatic pressure um can move the tube foots one way or the other and thus help with in a kind of wave motion with each uh a wave of tube feet moving um Al along the length of the arm uh can help the sea star locomote or move for example move food um into its stomach or help move food into its stomach so Ain derms have this defense mechanism uh pedestal pedestal um so these are kind of basically little uh Pines that are bounds to the test uh using coll with collagen fibers um and they have hinge and muscles are Associated uh which can both help um trap uh trap prey and predators just mention you have your ampul the TU feet include an ampul the amp ampul muscle and a Podium or the feet part of the CH foot okay so sea urchins are Class noia A quite well-known uh class including the West Indian Sea egg for example okay SE tend to be grazing you'll see them on the floor or in amongst kind of rocks uh in coral reefs or coastal areas um and also this includes uh the Sands dollar it's basically a kind of flattened sea urch and you may see these um I've seen them um on the beaches in uh the North Coast of Trinidad for example at Las quavas Beach uh just they kind of live just under the sand and they feed on Detroit Us in the sand in these coastal zones okay so the urchin as you'll know has a kind of um this hard test or shell and the the spines uh on the sea urin are attached to the test again with um with collagen and muscle and the muscle the collagen makes sure the spine attaches to the test of the muscle enables the SE urin to move its spines um so aiding both with defense and Locomotion there's an Atlantic Rock boring urchin um observed on n on n naturalists in the so kenoia or the kinoid another form of another class of kods um otherwise known as uh they could be known as seaes or there's also feather stars these are normally sessile so cile means they don't move they're attached to a hard substrate and normally don't move although uh feather stars can uh potentially detach from um their hard substrate and move kind of waving uh their um their tentacles I'll show you a video about on that in a second okay so when they sessile they held to this their hard um uh substrates with this hold fast and you have this column this stalk columnal stalk that attaches to a crab including These Arms or tentacles pineals on the end of the tentacles okay which help or with Filter feeding and occasionally with Locomotion here's a kinoid uh seen in of Domin on my naturalist the class H roia are the C cucumbers again quite wellknown class of a kind terms um including the West this West Indian Sea Cucumber okay you'll notice that compared with the urchins so the urchins have a um uh the anus at the top and the mouth at the bottom so the Abal surface is the anus and the oral surface is the mouth whereas uh C cucumbers have a similar sort of structure but they're basically on their sides okay so they we have uh a mouth anteriorly and an anus posteriorly okay this um this is also a c cucumber it's a deep sea C cucumber that has evolved um different means of locomotion uh using legs um compared with other um CQ compers okay so here's a a donkey Dum CQ um seen of the coast of Tobago okay so these can be economically important certain uh cultures in Asia um will eat these uh SE will eat certain sites of see cucumbers [Music] um uh but they they are found throughout Marine environments across the world the class asteroid here are starfish or other all sea stars another well-known class generally known as having this again this kind of pent radial symmetry with the five arms that we showing I was talking about before this is a West Indian sea star okay and they also have their um their mouth uh on the ventral side and they tend to eat through extruding uh they can eat through extruding their stomach contents outside of their body um to externally digest their prey okay and their prey can even include um such difficult to access items as clams so like this pastas this pasta species starfish is uh is feeding on a clam here so pulling the clams to this Biv valves shell open uh using that tube using its tube feet so using the water vascular system uh the kind of hydrostatic pressure and muscular system in the tube feet to pull apart the clam and then it will be exuding its stomach inside the clam to digest the clam um and extract the nutrients then has an example of a sea star scene off the coast of Western uh kind of Northwest Trinidad here brittle stars look a little bit like sea stars but they're in a different class so not asteroid here but uh aidia so you can see uh they actually have their organs their main organs inside the central disc rather than in ex extending also into um um the arms of the uh the star uh unlike the asteroida okay they'll tend to again have kind of three AR sorry five arms but also they have these five teeth surrounding a v again a eventally located mouth okay and they can locomote by um using chebe feet but also by actually uh physically uh moving the uh adjusting the shape of their arms so again you'll see here this top side of the AAL side of the bottom side of the oral side so the mouth um is is on the bottom side of the vental side then here's a sea star scene off the coast of or rather a bristle star scene off the coast of token on naturalist see there Central plates and five external or five attached thin arms okay so arthropods or arthropoda we're back to the protones now and they're ecton ECT ecton uh so they perform ecis they must um mol their outer skeletons uh in order to to grow okay so the outer skeletons uh do not grow of themselves whereas the inner living tissue does grow so every now and then they have to Mt these um external uh skeletons in order to grow larger okay the ancestral forms have been founds in the fossil records with um similar to arthropoda with kind of B or two branched appendages on each segment it seems that they evolved in the sea okay and the most basic living group of arthropods are the crossa uh which uh many of which do still uh exist in the sea but most of which still exist in the sea and Marine environments they they have these plantonic plantonic uh naous slav so um the lar um uh compos a certain uh percentage of what we know is know of in in the sea as Plankton which is actually makes is made up of all sorts of different types of organisms they're just very small and free free living in the sea and they have a cuticle uh they form a cuticle with which includes uh calcium carbonate okay they're paraphyletic rather than monoptic so they don't represent an entire um evolutionary branch on on its own then that we're going to look at some uh different classes Malo sta uh crabs and wood voice Max podia or the Barnacles and brania water okay so this is a CL pH arrra I'm not going to require you to remember all every single um taxin in the phm arthropoda okay there are one and a half million described insect species and it's very likely that most species are as yet undescribed there may be more than closer to 10 or even 30 million insect species okay but they are is an arthropoda not just insects they also it's also an even more diverse although insects may be the most diverse tax um you also have um cross Asia the MIAA and the Kiser all of which we will touch on in the next lecture on this in this lecture and in the next lecture okay so you might know notice this um FM onora which isn't part of the arthropoda but it's very close taxonomically and it's thoughts that they may be a precursor to the arthropods okay so this maybe velvet worms of onah Thora that we see um now may well be similar to the uh precursor organisms to the U or kind of ancestors of arthot this particular species is endemic to Trinidad they have a flexible cuticle rather than the stick cuticle that AR called sou okay this this photo was taken off by naturalist the North Coast of Trinidad again it's it's endemic which means it's not found anywhere else other than on the island of Trinidad okay so they have so ancient Sonic forign species now extinct species have been seen in the fossil records U particularly from what we know is the burgest buris shell which is a very old [Music] um deposit because about 8 million years old the mid Cambrian uh um from the mid Cambrian okay and it represents Marine sediments and many soft bodied fossils were able to be preserved in this okay so we know a lot about our the history of the evolution of um but we know a lot about the ancestors of invertebrates uh from this Burgis shell again um these species very similar to today onor onorin was uh found in the burish shell including as we see today colomar legs or Loba pods and a pair of antenni as well as we see in velvet worms now so mon modern onorin are uh The Velvet worms are specialized terrestrial prors okay and they spray this sticky secretion from these oral pillo um to catch their prey and also as a a defense mechanism okay and they give birth to live young rathers and eggs okay direct developments so likely the arthropods evolve from something similar to the Bel velvet worms okay so they develop evolve this exoskeleton a hard rather than soft exoskeleton it's a hard cuticle with including kitin which is a modified polysaccharide um um includes glucosamine units containing nitrogen okay this is also found in fungal cell walls okay inside the body you uh the uh the body is segmented and you have these segmental muscles inside the body and also inside the legs which combines with the this kind of stiff uh cuticle divided into plates uh can enable uh quite uh separate control for quite complex movements um enabling um efficient kind of locomotion and feeding behavior for example okay so you got this uh the the um uh um that they have this heal uh hemosil uh which is the cavity the body cavity um in uh arthopods as well as in mollis we mentioned before okay includes a uh they have a heart as part of their um circulatory s system uh vental nerve cord longitudinal muscles as well as dorso ventral muscles um and muscles within the appendage appendages as well as inside the body cavity okay the cuticle itself isn't just um uh hard plates okay but they also have pores enabling G gas exchange CER or kind of hair like structures um attached to set setti which can kind secrete um uh which can uh enable secretions um and then underneath you have this kind of living cuticle the living epithelium uh also endocuticle and exocuticle and these scleroids or um uh plates of the cuticle are attached by this kind of articular membrane which means that moving these muscles can move the plate enable um different behaviors okay so this is known as biomineralization you've got your living tissue uh excreting uh kind of mineral effectively creating a kind of minimal mineral layer above it as I mentioned these hard cuticles need to be molted in order to enable growth and also metamorph metamorphosis as you can see this sarda here okay so as I mentioned you have your kind of living epidermis um above it you got kind of new epicuticle being formed and then these kind of old epicuticle forms the external part of the um uh the cuticle and inside the uh endocuticle okay and as the new ticle develops you develop this gap between the new epicuticle and the old um cuticle which eventually enables so this is during premolt so molt is just about to happen and then that uh enables malol once the new epicuticle has developed enough but obviously the new epicuticle is actually going to be um softer than the old epicuticle so these uh arth reports need to be quite careful until the new epicuticle is fed and enough uh to be functional both in terms of movement and defense so here for example you can see an isopod that has molted just its back half the back half or the posterior end of the cuticle uh leaving the old anterior end and you can kind of see in this image um the difference okay the new cuticle epicuticle is is larger in size and uh softer okay but it's still quite cramped up front all right inside the living tissue is um has grown is uh needs uh space to grow hence wiring eventually this uh front end of the cuticle this anterior end will be moled very soon as well okay so arthropods this is a general uh anatomy of a crustation arthropod they generally have these compound eyes but they may also have simple eyes a heart uh stomach mouth and uh you know separate mouth and anus um stomach guts connected to uh connecting the stomach to the anus uh anterior gangion so effectively a brain in the heads um with nerve cords uh radiating out from that okay you may have appendages that are um specialized for Locomotion or the sensory appendages such as these antenna grabbing appendages in the case of this lobster for example mandiles are kind of mouth appendages or feeding appendages to mentioned the Hemo seals so these are found both in the Aros and the mollusks okay the cavity the body cavity of arthropod and also the body cavity of the mollusk is called the Hemo seal okay so hemolymph which is effectively know the the the um equivalent of blood is pumped by the heart along vessels and the arthropods then flows freely through the hemosil so it's an open circulatory system it's not as efficient as some closed circulatory systems we've seen or will see okay and then once uh the oxygen has um been uh used um or taken out taken from the hemolymph um it re-enters the heart uh through pores in AR arthropods and through veins in mollusks um in order to be reoxygenated and both arthropods and mollusks have respiratory pigments so we have hemoglobin they have the copper based hemocyanin okay in order to um in order to enable the uptake of oxygen into the um hemolin whereas the hemoglobin we have en able to and to enable uptake of oxygen into our blood okay so arrod eyes can be both compounds such as these larger eyes on this wasp or simple okay simple eyes have a single cuticular lens uh with reer at the posterior end okay a compound eye in this case lat cross-section lateral comp cross-section of a compound ey it shows how it has multiple lenses each attached to its own photo receptor okay so this is this is really a step up in terms of the sensory equipment that arthropods have compared to other F we've looked at up to now also in ter also um kind of sensory receptors have increased in efficiency and uh diversity through um kind of chemical and touch senses such as antenna okay insects have all sorts of different antenna types uh to detect uh could be kind of electrical waves or it could just be to detect movement or movement in the air for example um hence all the different types of antenni uh that have evolved okay they also have mechano receptors such as um the seti um uh attached to the cuticle or going through the cuticle which can uh uh detect movement or touch or anything touching the outside of the animal okay so I mentioned how diverse arthopods were okay today we're going to look at crustations um there's also in the next lecture we look at uh gicat including spiders scorpions tick myriapods including centipedes and mipedes and hexapods including springtails and insects okay so I mentioned tag uh uh tagmosis briefly previously okay so tagmosis is where you have um a fusion of segments to form uh specific uh areas of the body okay so let's say we have our ancest form of arthropods okay a segmented uh organism each segment apart from the first one is basically the same okay um but then let's say we have this kind of generalized uh look at segments in decapod crust crustation such as a uh a lobster for example you then have uh a number of different um uh areas of the body uh with different types of segments okay some of these segments will be similar within within the same area but different to those in the other areas so for example you may have a SE th thorax okay with specialized segments uh the heads and for mouth Parts an antenna um you may have an abdomen with uh swimmerets and walking legs um but this kind of fusion of segments can enable uh um a wide diversity of different functional uh functions to be performed by the same uh organism okay it's uh specialized body areas and specialized to perform different fun functions for the organs okay segment numbers May Vary here so this just kind of General generalized okay so let's say we looking at a Deca pod such as a shrimp okay you may have your seph thorax here made up of the head and the thorax um and that's formed of in this case 13 fused segments and an abdomen formed of six fused segments okay and within the abdomen you've got different um uh locomotive appendages specifically for swimming or uh swimmerets uh within the SEO thorax you got walking locomotive appendages as well as the kip heads um for grabbing and appendages uh that make up the mouth Parts antenna uh and the antenna um so all these uh segments have specialized and uh Fus to a degree uh to create this more efficient uh body form for for the shrimp okay appendages are these in crustations are by ramus okay so they have two uh two main um generally have kind of two main parts to them okay the endites the exopod the crustation lari are known as uh norus so I mentioned they're kind of um a part of the form part of the um planktonic ecos system okay so they tend to have this kind of one eye they also have these bonus appendages or anteny a hard sh shell and swimming Sati okay here's a lava of the Barnacle is's the lava of a crab okay they don't compete with their adult forms okay they feed they exist in different habitats they feed on different things uh so before they become adults they're not actually competing with the adults so it's efficient um separation of the Ecology of the lari and the adult for okay so in the class Malik sta you have the order decapoda so this is lobsters and shrimp so the shrimps are also decapods and this was an example of tagmosis in a decapod we looked at before there a lobsters and shrimps such many of which or several species of which are found in Caribbean and around shrim and too such as the Caribbean spa Lobster okay these have uh uh an they're anten for defense as well as for sensory purposes they they're important as a human food source and also e economically important the high economic value placed on them um so you also have uh red banded Coral shrimps and Marine shrimp in um Waters around TMT which have an ecological uh important ecological function uh as a cleaner for um other marine or organisms so call a cleaner symbiosis okay the shrimp gets food and the other organisms uh get cleaned and have a reduced risk of infection various infections as a result okay more other decapods include crabs so as we know they can be important economically including here in Trinidad Tobago for example blue land C you see being so side of the roads just like uh lobsters and shrimps have these Kelly Peds but they have this quite wide um short Ross carace um with a kind of a shorter um a shorter uh body but but with walking legs rather than and calipes rather than swimmerets although the um shrimps and lobsters do also tend to have orings okay they can they can be a important freshery um and they have there's some interesting kind of ecological uh there some also also some interesting ecological stories that could be told uh such as for example uh the migration of red crows in in Christmas Island okay so that migration is to basically from the lands or the forests of christen Island to the coasts where they then um uh release their their egg they do a mass release of their eggs again releasing their eggs all at once uh basically means it's impossible for any Predators uh to eat all the eggs all at once so some of them will to become uh marine lari and then adults and move back onto the land okay so the order I ofer um otherwise known as the woodlice or include the woodlice um or P pill bug sour bug they many of the many isopods unlike uh the vast majority of crustations are terrestrial although there are Marine plenty of marine isopods as well and they' also eventually flattened so they this kind of flatter body um and they they exhibit some uh parental um care as well both for the eggs and for the juveniles okay and you do see some of these around Trinidad and Tobago as well so here's one seene on uh um on monus island I think it was been an interesting uh quir um this is where I'm from uh in England um and these are all the different uh names that local communities give for wood life of these terrestrial isopods and when I grew up I heard people talking about cheesy bugs I thought that that was the name name for woodlice but actually it's only the name for wood Li in this tiny part of the world that I'm from all right so not just so these animals aren't just important economically and ecologically but culturally um all these animals that you're learning about can uh say a lot about human communities as well and the diversity of human communities all right so uh different class of frustations the brand branchiopoda okay these may be a little bit closer to the hexapods or the insects and some other cations we've looked at uh known as brine shrimps okay you can see they have a little bit of a different kind of body form to the other crustations we've looked at so far we have quite a thin body with uh quite long swimming and feeding appendages okay so a lot of these appendages can be used for Locomotion and for filter feeding they lack a a um the the carace or the large carace of the other classes we've looked at um and they survive in some of these survive in hypers can survive in hyp saline water and extremely um in extreme environments they're important as fish Foods they're also important in kind of environmental science for toxicity tests and they've been used um as very Hardy creatures to to uh they've been taken to space to uh test the effects of radiation also in the branko water fle water fleas you can see they have this these kind of enlarged B bamus second antenna which they use for Locomotion okay um uh very small crustations but also important so for example D species which are fresh water crustations also important as fish foods and also as a a pollution indicator freshwater pollution indicator okay and finally Max codo the Barnacles okay not everyone realizes these are crustations but um loua G said explained um quite quite uh accurately that a bacle is nothing more a shrimp likee animal standing on its head in a limestone house picking food into its mouth okay so they tend to be as in the adult format they'll be sessile attached to a hard substrate such as a rock or a whale or a boat okay and you'll have its um um uh it its legs or its appendages are for feeding rather than for Locomotion okay so its legs are Fe its appendages are featured around its mouth it will move uh food from the water or nutrients from the water into its mouth um but otherwise uh has the generalized format of of other crustations okay so this is the Caribbean Barnacle I mentioned um uh boats as a potential uh location for them and they can have an economic impact um once when you get enough Barnacles on a ship they can slow the ship speeds by you know up to 30 to 40% and require remove expensive removal okay so that's one of the reasons why you often see ships and dry docks so removing one of the things they'll be doing is removing Barnacles to increase uh fuel efficiency and speed of boats there's also uh other types of barnacles known as the goose Barnacles okay in ancient times in Europe anyway um because they look a little bit like a goose head it was thought that geese that stay that are northern Europe in the winter and then disappear um because that people didn't know about migration and the fact that they were flying elsewhere to their their breeding grounds um thought that these Barnacles that looked a bit like use heads um were actually the geese okay the geese were entering the sea becoming these Goose Barnacles and then in the winter they uh they come back to land again obviously that's not true but you know another kind of interesting cultural story um before we knew a lot more about some of these organisms all right so that's it for today's lecture and I will uh see you perhaps the next one