Utilisateur
topic 24- arthopod body plan + metamorphosis+ charactesrtics of arthopods+ characetsritcs of chelicerates + differentiating between arthopods
taxonomic phylogentic interpetation T3-T4
microevoltuonary chnages in popualtions T5+T7
terrestrial adpations of animals (theme 4)
derived chrodrate clades (T26-T33)
interepration of a phylogeny (T3,T4,T24 midterm 1 part 2 question)
fetaures of eukarytoic life cycles (relevent topics) 3 marks
arthopods account for 2/3 of all animal species
3-30 mil living species
segmented body plan
jointed appendages
hard exoskeelton
cambrian explosion
earliest arhtopod have little variation from segment to segment (trilobites)
-a decrease in the number of body segments
-an incrase in appendage specialization
-changes may have been caused by a changes in hox gene sequences or regulation
all arthopod embryos are segmented
_ the last common ancestor of arthopod probably had numerous undiffereitnated segments, each with a pair of appendages that functioned as limbs
into functional units (tagmata) with specialized functions
ex. the 3 part apperance of many insect bodies the two part apperance of spiders
head and thorax merged
-head: eating and sensing
-thorax: locomotion
-abdomen: digestion and reproduction
segmented body
jointed paired appendages
sclerotized cuticle composed of chitin
cephalization
reduced coelom
open circulatory system
jointed appendages, undergoing evolutionary mod for functions such as swimming, walking, feeding, sensory perception, reproduction and defence. appendage speiclation varies across tagmata, distinct roles for parts.
composed of chitin, forms a hard, light weight external skeleton (exoskeleton)
provides supportive rigid surface for muscles to act against
someimes involed the incorporationof minerals (biomineralization) ex. calcium carboante in crustacenas
it moults it
head region concentrates neural tissuees and is composed of several segments of specialized for feeding and sensory percetion
* arthopod heads have eyes, olfactory receptoes and antennaa that function in smell and touch
their primary internal caivty is a hemocoel which support the internal organs
- because they have strong segmented limbs they dont need the hydrostatic skeletons the coelom offers
hemolymph circulated in the hemocoel surronding tissues and organs
circulatory fluid in the open circulatory system of arthopod; respiratory oigments for oxygen transport
there is a large variety
in small aquatic arthopods gas exchnage is done by DIFFUSIOn acrosss the body surface
usually have gills that are modified appednages where as land one have book lungs or tracheal systems
subphylum chelicerta (spiders, scorpions, ticks)
subphylum myriapoda (centipedes, milipedes)
clade pancrustaceans (crustaceans, insects)
include both crustacens and hexapods molecualr studies suggest crustaceans are paraphyletic and hexapods evolved WITHIN crustaceans instead of being grouped together with myriapods
group of extinct marine arthopods, abudant and diverse in cambrian, flourishing for almost 270 MY became extinct during the permian extinction
- eskosleton is easily fossilized
segmented body with 3 distinctive tagmata
cephalon (head); throax (body); pygidium (tail)
-compound eyes, numerous lenses act together to create and image
- one pair of flexible antennae
each segment bore a pair of birmaous (two branched ) limbs
- ancestroal arhtopod limbs seem to biramous, ventral banch for locomtoion and the dorsal branch formas a gill
- most derived arthopods lost the dorsal branch (unirambous limbs)
paraphyletic
claw like feeding appendages
(spiders, scorpions and mites)
as marine animlas in the early paleozoic, earliest ones were large 2.5 m, widespread eurypterids (water scorpions)
- msot marine chelicerates are extinct but some surviv like horeshoe crabs
-two main tagmanta: anteria cephalothorx and posterior abodemen
- chelicerae mouthparts
- entirley or partially coverred by a carapce; dorsal exoskeleton section
- 6 pairs of appendages
chelicerae, pedilaps, 4 pairs of legs
No antenna
uniramous appendages/limbs
if eyes are present their are located on the cephalothroax
no appednages
contains digestive and reproductive organs
used for predation or defence
- modified apenednages that appear befor the mouth homologus to antennae in other arthopods
- 2 or 3 segmented fangs or pincers
- chelicarae in spiders are hollow contain venom glands
includes spiders, scorpions, ticks and mites
dominant chelicerate group with 100k species, mostly land
- most are fluid feeding (dont eat solids)
-simple eyespots (ocelli) that focus light though a single lens
- abdomen and cephalothoarx w 6 pairs of appendages (chelicera, pedilaps, 4 legs for walking)
-seperate sexes
-fluid feeding
-40k species
-2 segment chelicerae w posion glands
-tight constriction between cephalothorax and abdomen
-gas exchange via abdominal respiratory organs (book lungs)
- 0 to 4 ocelli
- spinnerets, silk producing (liquid protein) abodminal gland
- exhibit maternal care of eggs sometimes youth
- complex courtship especially good sight species
- 1750 species, desert/rainforest
-modified pedilaps as grasping pincers
-segmented abdomen, terminates in a posinous sting
- crush of string prey to death, externally giset bodycontent and ingest the digested fluid
- undertake complex courtship: male led dance
- female broods eggs beneath her, hatchlings carried on back
40 k species, microscopic
-no speration between the cephalothorax and abdomen (no segmentation on outsdie)
-2 or 3 segmented chelicera
-0 to 2 pairs of ocelli
- diverse ecology; parasites, predators, detritivores (solid particles), herbiovroes, soil, water plants, human skin, fluid feeders
- most econmically imporant arachinds (crop pests, used as biocontrol agents, medically important)
millipedes and centipedes
- land, no aqautic ones
- less tagmatized
- simple eyes (ocelli), 3 mouth parts (incl manibles main), 1 pair of antennae, numeorus legs, long trucks of jointed uniramoud legs
- gas exhange via tracheal system
- drect devlopment (no larval stage)
air enters lateral spiracles, through trachea, into tracheoles, throughout body, most lack 02 transporting pigments int the hemolymph
-12k species, tropical
-detritivores or herivores
- 2 pairs of jointed legs per body segment (diplosegment from fusion of arjacent pair of sigments--> class diplopoda)
- 3k species, tropical
- fast moving
- 1 pair of jointed legs per segment
- 1 pair of modified legs on the 1st trunk segment (venomous claws--> class chilopoda)
- few posinous to humans
crustaceans (subphylum crustacea; paraphyletic) and hexapods (subphylum hexapoda)
- myriapods are sister to pancrustaceans used to be gropued together with hexapods because they both had 1 pair of antenan, 3 pairs of mouthparts, respiration via trache and uniramous limbs but molecualr studies challenged this
incl crabs, lobster, shrimp and realtive, 40-50k species, marine, freshwater some are terrestrial
- huge morholgy size range (microscopic to giant)
- isopods, copepods, decapods
terrestrial, freshwater, marine speices (pill bugs are well known group)
small crustaceans, many of which are planktonic
realtively large crustaceans incl lobsters, crab, crayfish and shrimp
- 3 tagmata (head, throax and abrdomen) often a cpehalothroax
- cephalothorax covered by carapace (exoskeleton sheild coveres dorsal/lateral sides, sometimes the abdomen)
- biramous limbs
- 2 pairs of antennae
- compound eyes (often on stalks)
- branched biramous limbs
- exoskeleton strengthened by biomineralization
- gas exchange through the cuticle; larger ones have gills few have a tracheae
-head: 2 pairs of antenna, paired segmented mandibles (main mouthparts), 2 or more pairs of maxialle (taste/manipualtion of food)
- thorax limbs: locomotion, 4 pairs
- abodmen limbs: swimming, gas exchnage, filter feeding, or holding eggs
- calcium cabronate in cuticle
- in barancles; seesil crustacean, cuticle is hardened into a shell
- gills ; modified appednages in larger crustaceans (plate like or fluffly, well vascularized, thin unsclerotized cuticle)
- small ones use cuticle
- oxygen trasport by repsiratoy pigments (hemocyanin) in hemolymph
- few land ones use a trachea, branched tunnels to delive oxygen to tissues (woodlice/pillbugs)
hard to generlaize
-most seprate sexes and reproduce sexually (not sessile barnacles; hermaphrodite; rarley self fertilize)
- asexual parthenogeneis (embryonic devlopment without fertilzation fo diploid eggs) widespread in crustaceans
- sperm tranfer via copulation (sex), occurs via intromisson or spermatophore dpeositon (sperm capsule in femal opening)
- some females brood their eggs
- direct (daphnia) or inderect devlopment (1 or more larvarl stage; common)
- improant detrivores, scavenged, preadorts, parasites
-planktonic ones (coepods and larvae) are food for many vertebrates ( fishes and whales)
- some filter feed, incl motile (krill) and seessile (barnacles)
-
subphylym hexapoda: enormous clade incl. insects and their realative
-6 legged arthopods,3 pairs of legs on thoracic segments, no appendages on abdomen
- most diverse of all animals groups; 1 mil specis
-in all land and some freshwater habitats
-only group of invertebrates to evovle wings/flight
-diversfied mutliple time (adaptive radiation), following flight (feeding on gymnopserms and expansions of flowering plants)
protura; collembola (spirngtails)
-diplura (two pronged bristletails)
- consistent tagmatization
- has exchnage occurs through tracheal system via lateral spiracles
-head with 1 pair of antennae and 3 pairs of mouth parts incl manidbles
- thorax w 3 pairs of jointed uniramous legs w/wo wings
- abdomen wo paired jointed appendages
branched cutcile lined tubes carry oxygen directly to tissues, most lack oxygen transporting repsirator pigments in their hemolymph
pivotal evolutionary inovation
- several basal group lack wings (paraphyletic aprterygota-silverfish) some secondarily lsot their wings, ex.lice,fleas
- most insects have wings as adults (1-2 pairs on thoracis segments, wings are extenstion of the cuticle)
-wing sevolved only once, they are SDT of clade pterygota
- how and why insects got wings is unkown
-flight led to adaptive radiation of insects
- many undergo metamorphosis (inderirect development), proccess involving larval and adult stages with different morhpolgy, behaviour, ecology
-incomplete and complete metamorphisis
the juveniles, called nymphs,r esemble adults but smaller undergo multiple moults till full size with wings fully developing (grasshoppers and dragon flies)
progess through larval stages known as maggots, grubs or caterpillars
- larval stage has diffeent morhpolgy/ecology than the adults (maggot vs fly, caterpillar vs butterfly)
- wings develop all at ONCE during specialized pupal stage
no mos are either male or female
transfer sperm indirectly via a spermatophore (encapsualted spem)
copulation (sex)
- recognize memeber of their species visually, auditorally, or smelling
shed entire exoskeleton including cuticle invagiantions (lining or foregut, hindgut, trachea/tracheoles)
- new cuticle produced before moulting and is soft and wrinkled
- insect swallow air or water to expand the new exoskeleton
- predominatly land but aqautic larval staged
- key role as detritvores, aid decompostion and nutrient recyling
- essential food for other animals
- bees; pollinators, ladybugs/lacewings; biological control agents on pest species
- some are parasites of pests
clade opisthokonts which is part of the unikonta protist supergroup this is due to phylogentic realtionships among eukaryotes
- 1.3 mil animal species
multicelluar
heterotrophic
eukaryotes
with tissues that orignate from embryonic layer
(exceptions)
- mutlicellular eukaryotes except gametes, lack cell walls, cells /tissues connected by extracellular structural proteins (collagen msot abundant), tissues share function/strcuture, animal non reproductive (somatic) cells differentiate into specialized types (digeststion,s ecretion,transport etc)
- # of cells varies among animles 4-5 in simples one to over 100 in humans
- specalizied cells not foudn in other multiceullaur organisms: enruons (nerve cells) conduct impulses, contracible muscle cells responsible for movement, nervous tissue and muscles tissues are defining characterstics
- animals are chemotrophs rely on preformed ogranic molecules for both carbon and energy (like fungi)
- animals are phagotrophic heterophs ingest and digest food internally (in fungi its external absorptive heterotrophs)
- most reproduce sexually diploid (2n) dominating (in fungi haploid dominates), all life stages are diploid
- sexual reproduction meiosis produced haploid (1n) gametes, fuse during fertilization to form diploid (2n) zygote
- gametes of different sizes, eggs are large and non motile, sperm are small and motile
generate gentically identicle offspring froma single parents with fertilization/fusion of gametes
- found in half of animal phyla
- don by fisson,fragmentation,budding common in invertebrates
- animal splits into 2 or more parts that regenerate into complete organisms
formation of new individuals from outgrowths of existing ones only found in invertebrates
development of an embryo from an unfertilized egg cell, found among invertebrates and veretbrates
- rapid pop growth with favourable ocnditons
- alternative to sex when reproductive oppurunties are limited
- some species can alternate betwen sexual and asexual
occurs at many point in the life cycle of animals
- fertilization creates a spherical diploid zygote that undergoes embryonic development
diploid (2n) undergoes cleavge (rapid mitosis)
cleavage transform zygote into 8 cell embryo
in most animals continued cleavage produces multiceullar hollow blastula
hollow ball of cell surronding a central cavity called the blstocoel, only found in mebyronic development in animals
most animals undergo gastrulation forming a gastrula with diffeent layer of embryonic tissues
- cells from one end of the bastule fols inwards eventually filling the blastocoel produceing two layers of tissue (ectoderm;outer and endoderm;inner)
-gastrualtion is unique to animals
- archenteron (puch formed by gastrulation) opens to the outside via the blastospore
- most animals and ONLY animlas have Hox genes
- hox genes; curcial for evoltuion because they help determine body plan and segementation during embryonic devlopment
- hox proteins coordinate devlopmetn of strucutres along anterior-posterior (legs, antennae, wings, vertebrates)
- gox family of genes is higly conserved, arrangment of hox genes along chromosmes ramins similar across animal phyle, # of hox copies varies among animals (least in jellyfish, most in vertebrates)
-other developmental genes are conserved
direct & indirect
animal after birth or emergence from an egg is a small version of its adult form but just is nto sexually mature, no larval stages/metamorphosis
intervening stages ( larvae) with morphological and behavioural differences from the sexually mature adult stage
- most animals atleast have one larval stage
- larva is sexually immature, morhpolicaaly distinct undergoes metamorphosis to become juvenile
animals are motile, capblae of ussing metabloic energy to move in atleats one stage of their life
-marine animals with sessile adult forms have motile larval stages
distinct body plans, some have remainedd cosntient through evultionothers have had drastic chnage
ex. gastrulation has remained unchanged for 500 mil years
the symmetry of their bodies
lack distinct front and back or left and right, divides into numerous planes, often sessile or planktonic (drifting or weak swimming)
- most animals, distinct left and right side and single plane of symmetry
- associated with cephalization (devlopment of head region w sensory organs)
- specialized appendages for movement (grasping/defence)
- more active and have centralized nervous ssytem
anterior: front, dorsal: top, posterior: back, ventral: bottom
true tissues display aytpical embryonic devlelopment
ectoderm and endoderm
germ layer covering embryos surface gives rise to skin and nervous sytem
innermsot layer, lines the devloping digestive tube; archentron
have 2 embryonic cell layer; ectoderm and endoderm
radially symmetry--> diploblastic (cnidarian and few other groups)
aditional inerventing mesoderm gives rise to msucle an dother organs
- bilateral symmetry--> triploblastic
(arthopods, flatwroms, vertebrates and others)
a fluid filled body cavity
fluid filled space or compartment in animal body where internal organs develop
devloped by larger animasl during embryonic devlopment of the emsoderm
- lined by mesodermal tissue, forming betwen outerbody wall; ectoderm and digestive tract; endoderm
- coeloms have coelomic fluid
- mesoderm layer surrond the coelom conenct and corm structure to suspend internal orhans, allowing them to shift without deromation (heart beating ex), cusions internal organs, fluid filled ones act as a hydrostatic skeleton for soft bodied animals by tensing muscles agaisnt the incompressible coelomic fluid (earth worms)
many triploblastic animals have it, froms between the meso and endo, arises from the balstocoel, embyronic cavity of the blastula/gastrula
-animals with hemocole keep theri blastocel during mesoderm devlopment to form the hemocoel, hemoceol has simple embryonic origion so has evovled idnepently many times
- has hemolypm (fluid), analogous to blood circualted though open circulation system, together theu d nutrient transport, circualtion,waste remvoal and hydrostatic skeleotn
- coeloms and hemocoels have different embryonic orgins both can be foudn in some animal groups
no, small flat animal (platyhelmintes) dont need internal transport and circualtion system they just use diffsuion across the body
animals with coelomn, coleoms(hemocels) reduced or losst in several groups
-presenceor absence of coelms and hemocels is a not a good indicator of phylogenetic realtionshisp; dont form clades
protosome devlopment or deutrosome development
differeing in : embryo cleavge, coelom formation, fate of blastospore.
spiral & determinate
PSD Pussy sucking dick
each new row of cells twists, determnitae clevage; new cell is pretdermined. to for a specific part ( removal of cells; incomplete embryo; missing parts)
DRI dick riding idiot
- each cell is stacked: radial
- indeterminate: early stages of cleavege cells keep capcity to develop into a compelte embryo, enables formation of identical twins and embryonic stem cells
coelom form through splitting of mesoderm PS
mesoderm folds from the wall of the archenteron DF
blastospore becomes mouth PROTO first
blastospore becomes the anus while a second invagination form the mouth DETURO = second
- single common acnetsor; colonial flaggelted protist
-sponges are basal group
-eumetoza (true animals) clade of animals w true tissues
-most animal phyla belong to clade bilateria (billateral)
- 3 major clades of bilaterians, all re invertbrates (no back bone) except chordata which are classified as vertebrates
deuterostomia: hemichordates (acorn worms, echnioderms (starfish), chrodates. ecxhibits deuterstome devlop
ecdysozoans: invertbrates that undergo ecdysis (moulting) ex. arthopods: insects, arachnids, crustaceans
lophotrochozoans: feeding structure called a lophore, tentacle covered. others have a disticnt larval stage called a trocophore larva (mollsucs and annelids). some exhbit both proto and detuero
670-700 mya
the ancestral protists resembled choanoflaggeltes, which are flagellated euakryotes (opisthokont protists) closest realtive or animals
small unicellaular heteroptophic protists, 140 species, colonial forms (colonies), marine/freshwater, collard flaggelated with a funnel shaped collar of microvili at the bad of the flaggelum (microvillia cpature bacteria)
kind of look like sperm with little stick coming out of it
1. choanoglafgelate cells and cells of sponges are indetical
2. choanoflaggete cells are fond in other animals but not in non choanoflatte things
3. molecular phylogenies comfirm they are cloest livign realtives of animals
yes, led to devlopment of algae plants fungi and naimals
cell specilaization
increased size and complexity
longer lifespans
defence agaisnt predation
alage- 1.2 bya, orgin around 1.7 bya
neproterozoic (late proterzoic) 560 mya
1 bya-541 mya
- the earliest complec multicelluar animal fossils are the ediacaran biota (565 to 550 mya)
the rise of marine planktonic algae (archaplastids) 800-560 mya increased atmospehric and oceanic ocygen levels
-algal domiated ecosystems good for more effceitn nutrien and enrgy transfer
diverse soft bodies, mostly sessile marine organims, extinct by cambrian
535-525
- animal fossils show a rapid increase in the diveristy of bilaterian animals w complete digestive tract
- extant animals like sponge, cnidarian, mollusucs livign before the cambrian explosion
- evolution of predation: devlopment of more complex bodies/defnece
- ocygenation event; more oxygen bigger bodies and energetic lifetsyles
- evoltuion of hox gene: hox gene controls body plans of animals
the orodcian, late devonian and permian exctinctions
252-66
-dinosaurs were domiant on land along with mammals emerging
66- now
- age of mammals
conssit of 95% of animal species, occupy evry habitat, huge diveirsty, no backbone, inevrtbrates are parphyletic not a clad.
basal animals lack true tissues (informally known as sponges)
- 5500 living speices/ marine environments/ few mm height
SESSILE, but motile larave
they have no internal organs muscles nervous or circualtory system and only a few specilaized cell
from spicules and spongin
tiny needles or rods of silica or calcium carbonate that help maintain shape and structure
fibrous collagen protein network for support
porocytes
epidermal cells
choanocytes
mobile amobeocytes
tubular cells that make up the pore of a spong, allowing water flow
form outerlayer of tightly packed cells
epidermis seperated from choanocyte by mesohyl (gelm non cellular matrix), provides support and structure. comtain mobile amobocytes and spicules or spongin deposited by amebocytes
in mseohyl, they transport nutrients to other cells, produce spiclues and can differeiante into other cells
(collar cells) line the inner cavity of the spong (spongocoel).
make water current by beating flagella and suspedn food particles, deliver 02 and nutrients to smong and remove waste adn co2
suspension feeding, capture food particles suspended in water passing though them
- water is drawn by beating choanocyte flagella through pores (ostia) in the spongocoel and out thro an opening (osculum)
colalr cells extract protist planton using mucus covered microvili which are englufed through pahocytists and igested through endocellular digestion or transfered to amobocytes with transport nutrients to other cells to make spicules
hermaphordites; posses both male and female reprudctive parts
- no gonads (reproductive organs)
sperm comes from choanocytes
eggs come from amobocytes
can be both but internal is more common, zygotes devlop into MOTILE cilliarted larvae within th emesohyl, embyronic devlopment is highly variable
yes through fragmentation and by budding
sperm from choanocytes, sperm relaesed externally through osculum, eggs from ambocytes, choanocytes of the "female" trap spem and bring them to amobocytes/eggs which are retained in the mesohyl, fertilzation and embryo development in mesohyl, motile larvae relased from parent, larava devlop in water becom simair to adults and sessile, larvae attached to a solid susbtrate to compelte devlopment
- clean water through suspension feeding, filtersthorugh 1000 kg of water to grow 1 kg of mass
- produce toxic chemicals make them unplatable to predators, homes for some organisms
- soft sponges are used for bath and art purposes
- many form symbiotic mutalisms with unicellular algae (limits distrubtion of sponges to the photic zone; aread where light can penetrate water)
all animals exlcusing sponges and few other groups
- presence of TRUE tissues
ctenophora
cnidaria
- share similar body plans but not closley related, exhbit radial symmetry-->diploblastic
- posses muscle and nerve tissues but no CNS or cephalization
earliest descendant of eumetoza
sessile and mtoile forms, jellyfish, coral , sea anemone (10000 spp)
- radial symmetry--> diploblastic
sac like body plan
central gastrovacular cavity (digsetive) with single opening (mouth&anus in 1)
- tentacles have stingin cells (cnidocytes) around single opening
- body has outer epiderm derived from ectoderm and inner gastrodermis from endorm that lines the gastrovascualr cavity
- epiderms and gastrodermis seprated by mesoglea jelly
- gas exchnage via difussion across the epidermis
sessile polyp
mtoile medusa
attahced to a substrae, oral end upwards (sea anemone)
bell shapes, moves freely, hydrostatics skeleton, oral end downwards
tentacles to capture prey, armed with cnidocytes (explosive cells)
- contain complex organelles (nematocyts) deliever stinging toxins
bulb shaped capsule containg a coiled tubular thread, when triggered (mechano-chem recptor) is started, thread is ejected, toxins are injected
- tentacles move to prey to digest through gastrovascular cavity
medusozoa and anthozoa
all cnidarian that produce a medusa stage in their life cycle
hydrozoan
scyphozoans (jelly fish)
cuba zoans (box jelly fish)
cnidarains that occur only as polyps, soilatry/colonial forms ex. coral and sea anemones
alternate between polyp (sessile, colonial, asexual budding) and medusa ( produced asexually through budding of polyps but reproduce sexually) forms
- motile larvae settle transofrm into polyps
alternating between sexual and asexual in medua both are diploid (2n)
medusa is th emost predomiant stage from most true jelly fish
- coastal one shave breif polyp oceanic have none
- hydrostatic skelton to pove (contraction/pulsation)
- some activley swim, some pasisvely float
- made of mesoglea jelly mostly of water
medua is the predomaint life stage of most cubozoans (box jelly fish)
- often have highly toxic cnidocytes which can cause cardiac arrest and eath within minutes
corals and sea anemones
- occur only as polpys NO medusa stage
- see anemones usally single but corals are colonial forming thorugh asexual budding/fission, gain nutrion from symbiotic algae, some secrete a hard exoskelton of calcium carbonate which are crucial reef building organisms
reef constructon, coral bleaching due to the loss of symbitoic alage is a symptomatic of warming oceans
jellyfish bloom indicate cosystem stress, booms are from overfishing of jellyfish rpedators and eutrophication (nurtient additon) which inc zooplankton abundace on dec. O2 levels
- toxins from cubozoan are fatal to humans
bilateral symmetry and belong to clade bialteria, meaning htey are triploblastic with a mesoderm
- protostomes and deutrostomes two major groups of bialteria
- most of them have a coelom (body cavity) and digestive tract with both a mouth and anus
present in bilateral animals
sensory and feeding strcutres are concetraed in the anterior region as a head region
- concetration of neural ganglia forming a rudimentary brain
- sessile bilaterian (sedentary) have reduced cephalization
phlyum acoela
diverged before the emergence of 3 primary bilaterian clades
- majority are marine warms that feed on small organism, or organic detritus
- small flat body with minimal cephalization simple nerve net (no brain)
- no coelom or hemocoel (body cavity) or complex organs
- simple disgetive system w a mouth but no anus or gut
use endocelluar digestion 9digestion through individual cells)
genral term for animal w a body wo shells or elaborate appendages, longer than it is wide
lophotrochozoa
ecdysozoa
detuerostomia
defined by molecualr phylogens; some realtionships remain unclear
- includes half of all animals phyla (17 phyla)
- no single unifiying characterstic, wide rnage of body plans simple to complex, some eat rhough lophhore some through trocohpone
- incl, flatwroms, rotifers, ectoprocts, brachipods, mollusc, annelids
- mairne, freshwater, damp habitat (2ok species)
- triploblastic but no fluid filled body cavties, incompelte digestive tract (no anus but gut & mouth), some dont have mouth and gut
- no circualtory or gas exchnage system, gas exhnage across body aiden by dorsoventrally flattened shap that maximizes SA
catenulida
rhabditophora
chain worms, less diverse, freshwater habitats, reproduce asexually (budding)
-more diverse, free living/parasitic species
-well known species (planarians)
- also parsitic spcies
-freshwater, preyon smaller animals
- external anteria cephalization, lightsesnitve eyspots, pair of ganglia (dense clusters of nerve cells ) extend to pair of central nerve codes (CN net)
- gastrovascualr cavity w 1 opening, no anus only mouth
- hermaphordite, can sex or asexual-> fission
- trematodes and tape worms
- suckers/hooks, tough outer covering, complex life cycles w 2 or more hosts: intermediate hsot(asexual) and definive host (sex)
parasitize a wide range of hosts, complex life cylcles, alternate sex and asexual
ex. blood flukes causeing anemia and diraahe
parasites of vertebrates
- entriley endoparasitc in the digestive system of other animals
- they lack a digestive system get nutrient from hosts intestine
- scolex --> suckers/hooks
- posterior of scolex is a long chain of proglottid segemtns that have hermaphrodites (male and femal sex organs)
- new protologits at the base of scoles; older ones near posterior, mature fill w fertilized eggs which leave the host through feces
- fertilzied eggs consumed by intermediate host, devlop in larvae that encysts tissues in I host, I host is eaten by defintive host, larvale devlop into adult tapeworm in the gut of D host, fertilized eggs produced by sex leave D host through feces
pork/ beef tape worms and fish tapeworm
have the feeding strcutre; lophorphore ( fan of cilliated tentacles around mouth)
- have a coelom
ectoproctah and brachipods: both sessile but have motile, planktonic larval stages after sexual repdroduction
sesisile colonial aniamls , look like coral
- more diverse than brachipods; mostlu marine
abudant in th epaleozoic
-most have a hard exoskeleton (gelatinous or chitinous), colony members secerte caco3 tubes, ecotoprocts are capable of both secual (most are hermaphrodites) and asexual (budding)
- rectracbtale lophophore for suspension feeding, gut is u shaped, w anus outside of lophore
- lamp shells, resemble bivalve molleuscs, marine attach to seafloor by stalk
- feed using paired lophores (have complete gut and sometimes anus)
- highly diverse during paleozoic, dominant reef builders during then
mollusca (snails,squid, octopods,clams etc) and annelida (segmented worms)
early embryonic devlopment incl microscopic motile trochophore larva
- trochophores are planktonic larva chacracterized by 2 bands of cilia that faciliate movement and guide food toward mouth, above the cilia is a sensory plate and simple spot
snails, slugs, oysters, clams, octupses, squid
over 100 k species very diverse
predoamianty marine, some freshwater and land
- soft bodies animals protected by hard calcareous (calcium carbonate) shell, shell is reduced or last by some taxa, mollusca stemmed form soft bodies of octupses and cuttle fish
- muscular ventral foot for locomotion
- vsiceal mass above foot contain internal organs (reduced coelom in mass other organs in hemocoel)
- mantle is a thin tissue layer tha secretes the shell, often involved in reperation and extretion by forming water filled mantle cavity
- BODY IS UNSEGMENTED
usegmented, gills in the mantel cavity for gas exchange soemtimes feeding
- most feed using rasp like radula (scrapes/cuts food)
- most have open cicrulatory system, heart pump hemolymp through artierties into hemocoel, bathing organs
- most have seperate sexes, many snails are hermaphrodites
- life cycle includes a cilliated trochophore larval stage
-Polyplacophora (chitons)
-gastropods (snails and slugs)
-bivalvia (clams, oyster, other bivalved)
-cephalopoda ( squid, octupuses, cuttlefish, chambered nautiluses)
chitons: oval shaped marine animals (1000 sp) with shell and 8 dorsal plates, use foot as suction cup to stick to rocks, and their radual to scrape algae
slugs and snails (70k speices- 75% of living molluscs)
-most are marine, some are freshwater and land
- aquatic gastropods have trocophore larvae while land snails have direct development of juveniles
- most have a single coiled tubualr shell secreted by the mantel (for dehyrdration, predation, protection), some have no shells--> slugs
-land snails and slugs dont have gills mantle cavity evovled into a simple lung
- ventral foot or cilia action to move
- herbivores that use radula to scrape
- STRONG cephalization --> well devloped head with mouth, neural ganglia (brain), antenna, eyes
mostly marine (aqautic) 20 k species
-clams, oysters, mussels and scallops
- shell divided intwo two halves drawn togetehr by adductor muscles, some have eyes and sensory tentacles at edge of mantle
- some are seesile (mussels), most are sedentary some have limited mobility -- clams can dig with their foot,s callops can swim by clapping their valves
- suspension feeders, use gill in mantle cavity for gas exchange
- LACK CEPHALIZATION no head no radula
- economically important
- some invasive pests
squids, ocutpuses, cuttle fish and chambered nautiluses (900 spp)
- no external shellm lost during their evolution except in nautilluses
- long tentacle around mouth, evovled from mollusc foot, has suckers
-predatory, radula is modified biting beak, posinous salvia immbolizes prey
- some octupuses and squids use their siphone (fused tube of matnle) to fire water to swim quickly , most octupses creep along seafloor for prey
- only mollusc with CLOSED circualtory ( for active lifestyle, jet propulasion muscles might squeeze blood out of area where needed)
- well devloped sense organs/complex brains, excellent vision, complex behaviour
- hatch as direct devloping juveniles resmebling mini adults, NO trochpore larvae
segmented worms (series of fused rings; annuli)
- wide array of amrine and freshwater over 22k spp
- earlier taconomic classifiation consider 3 classes polychate, oligochate, and hirudinea but now they are paraphyleitc
- molecular phylogentic indicate 2 major annelid clades
clade errantia
clade sedentaria
- segmented bodies, w each segment having ismilar internal/external anatomy seprated by internal paritions called septa
- annelids have COELOM 9fluid filled body cavity)--> fucntion as hydrostatic skelton
- CEPHALIZATION, well devloped mouth, NG(brain) posses complete digestive system both mouth and anus
- closed circualtory system
mobile, marine organism; often predatory
-paddle like or ridge like strcutre PARAPODIA on each segemen, each apradoium has numerous chaeta made of CHITIN, external gills associated with parapodia
- parapodia not uniqe to this clade
- typiccaly have differenited head with sensory attenae and eyes
- reproduce sexually by free spawning, eggs/sperm relaesed in water, external fertilziation hatch in twochophore larvae
generally less mobile than errantian, some burrow in substrate some live in protective tubes (these one have elaborate gills or tentacles for suspension feeding)
- many lack parapodia and have reduced cephalziation
- some undergo direct devlopment withouth trochphore larval stage
- includes LEECHES and eartwhorms
predomaintly in freshwater, can be land or marine
- NO PARAPODIA OR CHAETAE
- pedators of inverbrates, parasites of blood of veretbrates (secretes anesthetic/anticoagulant, used tobe used for general cure for aliments)
- simulatenous hermaphordites typically reproduce thoughr eciprocal fertilziation, direct devlopment without larval stage
- NO parapodia
- 4 PIARS of chaetae per body segment
- earthworms and leeches are hermphrodites but cross fertilzie by reciprocal fertlization
- earthwroms do not free spawn, some asexual (fragmentation0, undergo direct devlopemnt in gelatinous cocoons (no larval stage)
- hydrostatic skelton
- less morhpolgicalay diverse then erranitan
- ingest soil and digest organic matter aiding soil formation and maintence of fertility ( turn over and aerate soil)
- msot speices rich animal group
- consits of 8 phyla ( defined by moelcualr phlyogeny)
- MONOphyletic group
- two prominet phyla; nematodes (most nuemroud animals) and arthopods (msot biodiverse animals)
ENA eating nasty ass
covered by cuticle that is periodically moulted (SDT)
- cuticle is a tough, non living outer layer of organic amterial deposited outside the epidermis
epidermal cells secret cuticle, cuticle is composed primarily of CHITIN, long chain nitrogenous polysaccharide
acts as a barried agasitn dessciant and mechanical injury
- strctural support, forms otugh external skeelton (exoskeleton), shaped body, good for muscle attachment
- non living outer layer no capacity for growht or modification
- they shed this entire cuticle to GROW thorugh ecydsis (moulting)
endocuticle (within)
exocuticle (outside)
epicuticle (upon)- thing waxy water resitant outerlayer (no chitin)
procuticle (chiting)--> endo and eco
outside to inside epi, exo, endo, epidermis with fine ducts runi from epiderm to top of cuticle
simialr with most ecdyszoans although cuticle compositon varies
- ecdysis allow for them to grow incremntally facialting changed between devlopmental stages, metamorphosis
- allows damged tissue and missing limbs to regenertae and remove external parasites
cuticle is often sclerotized in arthopods
cross links the chitin polymers w protein to harden and make cuticle more rigin, onyl specific regions are sclerotized (called scelrite/ when shaped like plates), used as armoud plates and hardened appendages that function as tool or wings
-
cuticle BETWEEN sclerite remains unsclertozied , unscleortized cuticle contain unmodified chiting that is pliable, flexible and movebale)
begins internally before external signs
1) ecydzoan become sinactive, old cuticle seperates form underlying epidermis (apolysis)
2)inactive enzymatic moulting fluid secreted in seperation space, epidermis grows (cell proliferation), inc. epidermal SA (folded)
3) new proepicuticle-thin portetive layer ontop of epidermis
4)moutling fluid enzymes (chinases and petidades) activated, old endocuticle DIGESTED (absobed by epidermis to be used for new cuticle), sclertoized exocuticle not digested, new undifferiented procuticle layer is deposited benateh proto-epictuticle protecting new procuticle from getting eaten
5)moulting fluid reabsorbed
6) depostion of new epicuticle completed
7) old exocuticle/epicutle is moulted, ecdoyzoan may swallow air or water to split old cuticle, new cuticle expans (larger ecdyzoan), SA of the new cuticle is bigger (wrinkly at first)
8) outer layer of new procuticle is sclerotized by secretion via cuticle ducts to for exocuticle above unsclertoized enoducticle ( can take sevrel minutes or days)
round worms or threadworms
- numeroud animals, found in aqauitc, soil,plants, animals
- wide size range, 25000 species
- morpholigcally SIMPLE BODY PLAN (secondary simplifcation): NO SEGEMENTATION,APPENDAGES AN EYES, blunt anterior, pointed posterior
- complete digestive tract NO CIRCULATORY
- must moult cuticle to grow
yes, body vacity is compeltely lined by mesoderm tissues tho
side to side contraction, typicaally sexual reproduction, most have two sexes some are hermaphordites, internal fertilziation and direct devlopment
soil neamtode, moderl organism for animal developmet organism bc of its well characterize dbiology, protosme embryonic devlopment
free living in organic substraes, predators or microbivores in soil, freshwater, ecosystems
- decompsotion and nutrient cycling roles
- some are parastic like tropical diseas caused by filarial worms and guinea worm
-n shared evlopmental charactersitc of bilateria, bilateral symmetry--> triploblastic
-undergo DEUTROSTOME devlopment which mean DRI, coeloem forms when mesoderm folds archeteron wall, formation of anus forom balstspore mouth second
-some non deutrsomie aniamls share deutrosme devlopment
- clade deutrosmia is defined by moelcular phylogeny
hemichrodata (acorn worms)
echniodermate (echinoderms, incl starfish and sea urchins)
chordata (chordates incl. vertebrates)
starfish, brttile sea starrs, sea urchins, sea lilies, sea cucumbers, 7000 spp all marine
found throughout ocean depth from intertisal and abyssal zone
-arose in the camrbian extensive fossil record 13k fossis, calcarous ENDOskeleton sutied to fossilziation
- SLOW or sessile
- 1) most ADULTs are radial/ pentaradial is most commont, mouth at center face downard (sea cucmbers are secondalriy bilateral)
- echinoderms evovled from bialteral ancestor (camrbian) evovling radial symmetry, echinoderm larva exhbiti BILATERAL symmetry
- 2) thin epidermis covers endoskeleton of ossicles, ossciler are calcareous plates spines in the dermis, body wall may have 10s to 1000s of ossicles
-3)unique water vascular system
4) diffuse nervous system w no centralized brain
5)seperat sexes, typically broadcast spawners
derived from the coelom consits of a ring canal in the central disk and a network of hydraulic canal running down the length of each arm
- radial cannal branch into hundred of fluid filled msucular tube feet for locmotion, feeding,respiratin,uscus production or sensory perception
- tube feet controlled by water pressure on ampulla and podium attach to substatres through suction and adhesive mucus
- water wascular system connected to seawater thorugh madeporite (porous ossicle, alows water flow)
- water vaascual system used for circulation and respiration, gas exchnage through simple gills and diffusion through tube feet
the central disk has a nerve ring and radial nerves extending into arms NO centralized brain
gametes relased into open water for external fertilziation no parental care of planktonic larvae
- some species free spawn but femal retains and broods fertlized eggs
crinoidea (sea lillies/featehr stars)
asteroidea (star fish/ sea stars and sea dasies)
ophiroidea (brittle stars) A&O together asteroza
echinoidea (sea urchins and sand dollars)
holothuroidea (sea cucumbers) E& H together echinoza
- diverse adult body forms amonsth them, different in devlop regulation of a signle hox gene cluster
starfish/sea star sea dasies
- 5 or more arms radiating from central desk, undersurafce of arms bear tube feet which grip substrate
-predators that have impact on intertidal community strcutre, eat molluscs pry them on open, evert stomach onto prey to engluf them
- some species asexually reproduce (fisson of their central disc)
-many can regenrate limbs
includes sea urchins, sand dolalrs
- NO arms but 5 rows of tube feet
- slow ( uses spines;jointed ossicles) for locomotion
- urchins are HERBIVOROUS use jae like plates to grind alage
- overhasrting of them leads to sea urchin explosion that descimate kelp forests
sea cucumbers- tube shaped detritivores
-depoist or filter feeders
-appear bilateral but secondarily bilateral, elongated, rows of tube feet along body, some have them aroun dmouth as feeding tentacles
- lack external spines and the endoskelton is reduced to scattered ossicles
bilaterally symmetrical, coelomates, segmented bodies
- share embryonic devleopment features with echinoderm but evovled speratley for the past 500 mill Y
-majority of chordate species have VC; the vertebrates subphylum
- consits of all vertebrates, 2 groups of invertebrates, urochordtes, cephalochordates
some traits only evident during embryonic devlopment for some taxa
1) dorsal hollow nerve cord
2) notochord
3)pharyenal slits/clefts
4) muscular post anal tail
longtudinal flexible nore located dorsally between digestive tract and nerve cord, glycoprotein core in collagen fibres
-provides flexible skeeltal support for invertebrate chordates
- forms during embryogenesis when organs begin to devlop embryonic layers
- develops from the dorsal mesoderm present in ALL chordate mebryos some adults
- in vertbrates a more complex jointed skeleton; VC replaces notochord, adults only have remants of embryonic notochord as parts of vertebrate discs between vertbrae
- nerve cord of chordate embryos develops from a plate of ECTOderm rolling inward forming neural tube dorsal to the notchord
- signnalling moelcues form notochord and mesodermal cells makes neural plate form from the ectoderm
- neural plate curves inward forming neural tube which devlops into CNS (brain and spinal cord)
- DHNC is uniqe to chordates other animal phyla have VENTRALLY SOLID nerve cords
-embryonic arches develop into pharynx posterior to mouth
-pharyngeal cleft between arches devlop into slits that open outside of body in aqautic chordates (allows water flow through mouth and out slits not going in digestive)
- filter feeding strcutre in invertebrates, gas exchange in aquatic veretbrates (excl.tetrapods), gill devlop along arches, which vetilate water, arches only present during embryonic devlopment in tetrapod precuroses that devlop into different elements of head and neck
-most adult chordates have msucular tail posterior to anus, digestive tract of most non chordates extend full bdoy length
-tail has skeletal and muscle elements, provide propuslive force in aqautic ones (fish), tail functions as rudders/provides grip and balance
- in some tail is greatly reduced in embryonic development
- segments are highly specilaized and in most chordates atleast during embryonic development
- segmentation evolved INDEPENDLTY from other phyla
, primitive character of detuerstomia
- segmentally arrange muscle blocks are present in all adult chordates EXCEPT urochordata
- musscle blcoks arrange in chevron patterns, muscle blocks devlop from mesoderm blocks (somites) that flank the notochord, altnerating contraction of muscle blocks makes nothcord/vc go side to side (swiming)
lanceletes (subphylum cephalchoardata)
- blade like body shape 25 spp
-resemble bony fish but are INVERTEBRATE CHORDATES
- marine sedentary suspesion feeder that have chordate body plan as adults, wriggle backward in sand, water into mouth by cillary actions, particle are extracted with musuc covered pharyngeal slits through atripore, mucus net ingested
more closley related to VERTEBRATES than lanceleted
-suspension feeding INVERTEBRATE CHORDATES, msot adults are SESSILE (sea squirts/tulips) attach to rocks, other are pelagic
tucinate larval stages msot closey resmble chordate body plan, have the 4 chrodate SDT
- adults dont look like chordates, tadpole larva (free swimmers), attach by head to substrate, memtmorphose to adultbody--> sessile suspension feeders
-adults covered by tunic (tough polysaccharide)
- draw water through incurrent siphon; filtering it thorugh mucus covered pahrygenal basket that collects food particles; water exits out excurrent siphon
- some asexual reproduction by budding forming colonies