337 final exam review ( porifera to chordata)
Terms in this set (122)
simple body plan without tissues or organs, basal resemble protist choanoflagellates whose cells closely resemble sponges collar cells. most primitive.
sessile, multicellular, filter feeders, cellular level of organizations lack nervous, digestive, resp, excretory systems. colonial and sessile but larvae free swimming all aquatic.
Porifera Body Plan
networks of pores, canals and passageways. water is pumped through smaller ostia and exists through osculum. animals filter nutrients as water currents flow through. spongocoel: inner chamber, canal system has evolved to maximize water flow by increasing surface area.
Types of body plan
asconoid: simplest type, small tube shaped sponges with a large central cavity with 1 osculum.
syconoid: derived from asconoid, more branching has incurrent canals and side passages but still has main spongocoel with single osculum
leuconoid: most complex, an almost unlimited ability for the sponge to grow in size, larger colonial forms each mass has its own osculum, incurrent and excurrent canals.
only a few cells have been specialized
most are totipotent which is an important key to their success.
flagellated cells with sieve like collar that acts as a strainer, flagellum creates a water current food is absorbed by collar cell and sent to other cells.
epithelium, lines inner passages some are contractile, myocytes in circular bands around oscular to regulate water flow.
tubular cells form the pores of asconoid sponges
amoeboid cell in mesophyll matrix,receives particles for digestion, phagocytize old cells, act as a primitive and simple circulatory device to transport nutrients from cell to cell. differentiates into scelerocytes: spicules, spongocytes: spongin, collencyotes: collagen : maintain shape and keep pores around canals open
sexually or asexually through budding. sperm and eggs can be formed by archaeocytes hermaphroditic.
Class Calcarea: asconoid, marine spicules made of carbon carbonate all three canal system
Class Hexactinellida: glass sponges with siliceous spicules - chitinn. 6 rayed syconoid or leuconoid synctytial and lack pinacorderm
Class Demospongiae: largest class, almost all leuconoid, may be spongin or silica spicules but never Carbon carbonate diverse marine and fresh water habitats.
first animals to have a definite shape, may have been first animals to swim, all aquatic but widespread in marine habitats. tissue level of organization.
radial symmetry, diploblastic with mesoglea between cell layers that contain amoebocytes that are used for storage, digestion and defense. polymorphic alternation of forms between polyp and medusa forms.
incomplete digestive cavity
no circulatory or nervous system, have nerve net that transmit impulses in several directions at once. have simple organs. polyp: tubular sessile body with upward facing mouth little mesoglea
medusa: sexual motile, contraction of bell downward facing mouth surrounded by tentacles. with a thick layer of medusa.
contains cells that cover and protect also contain nervous, sensory, gland cells for attachment, epitheliomuscular celles cover outside of body.
hydrostatic skeleton that muscles layer contract against.
ring of tentacles armed with cnidocytes that are used for feeding and defense. inside each is a harpoon like nematocyst a highly coiled tubular thread with a trigger like cnidocil that discharges due to high osmotic pressure when stimulated to discharge water rushes in and forces the thread out with great force it turns inside out. the thread penetrates and inject paralyzing toxins.
at margin of bell between lappets contain sensory organs, ocelli and chemoreceptors.
planula larva, sexual and asexual stage. that reproduce through budding.
Hydrozoa: polyp stage dominant, medusa stage for sexual stage and dispersion. digestion is intracellular through gastrodermal digestive cells that phagocytosize and extracellular gland cells secrete digestive enzymes. locomotion gliding on basal disk, reproduce by budding, usually colonial no cells in mesoglea nematocyts only in epidermis
medusa stage dominant, no velum oral arms rhapolia for sensory functions, gastrovascular cavity with gastric pouches with radiating canals, external fertilization ciliated planula larva grows into polyp
Corals, no medusa, GVC divided into compartments mesentaries , mouth surrounded by hollow tentacles, thick heavy cylinder, polyps solitary or colonial, marine only.
acoelomate, no body cavity around digestive system, triploblastic mesoderm allows for the formation of more elaborate organs, more specialization and greater division of labor. true organs made of different tissues organs are embedded in tissue not in any body space. protostomes, bilateral symmetry which allows cephalization more efficient in search for food and mates.
Cestoda- tape worm endoparasite
Trematoda- endoparasite flukes
free living: a single layer of ciliated cells
parasitic syncytial layer that lack cilia
circular and longitudinal muscles.
thick muscular pharynx
secretes enzymes, suck liquids, extracellular digestion.
carnivores or parasitic. incomplete digestive tract and in some highly branched or some completely lack a digestive system
gas through body wall
nervous system: distinct head with sense organs ocelli cant form images auricles contain tactile cells, chemoreceptors, ventral nerve cord some turbellaria have statocyst this enables faster reactions and more controlled movemement
protonephridia tube closed at one end and exiting at other end. flame cells- cup shaped area with tuft of flagella that create current to send wastes through tube which opens to outside of body. a way to contain water balance because they cannot be on land without it.
monoecious: cross fertilization some marine species provide a planula like larva.
asexual: fission, regeneration, budding
easy access to food and protection
but must be able to overcome host defences as well as not kill host and being able to locate and infect new hosts. must be able to penetrate and attach to host using hooks, suckers, have resistant eggs and have a large reproductive output. reduction in unnecessary structures such as a digestive system. hermaphrodite complex life cycle resistant eggs.
paraphyletic, multiple free living groups represented.
free living, ciliated epidermis that secrete mucuos trail asnd uses cilia to glide on it. rhabdites discharge into water swell and form protective mucous sheet around the body that release toxins to subdue prey and escape predators only ventral surface is ciliated. incomplete digestive tract mouth no anus, pharynx extends prehensile to get prey enzymes digest prey intestine further digest in the lining of the GVC. intracellulary. GVC extends to most part of the body undigested food is egested through mouth. excretion interconnecting series of excretory canals- water balance nervous system 2 longitudinal nerves extend each side of body with enlargements at the anterior forming a simple brain
syncytial no cilia muscle layer embedded integument
reduced sense organs.nervous and digestive system
hooks suckers structures for penetration and attachement to hosts. hermaphrodite, large reproductive ability resistant eggs. epidermis forms tegument
ectoparasite on fish direct life cycle with single host, egg hatches into ciliated larva and adult have larger posterior attachment organs with hooks.
endoparasite: no head, scolex special organ for attachment has hooks and suckers. body consists of a long chain of reproductive sacs = proglottids bud from scolex with oldest ones furthest. strobila= chain of proglottids. body covered by a protective cuticle no digestive system absorb food through skin each proglottid acts as an individual any two proglottids can exchange sperm require intermediate host.
body cover is a cuticle that bears bundles of setae.
bilateral symmetry, triploblastic, tube within a tube, true coelom. mesoderm development of complex organs, with muscle layers, allows for circulation of fluid , provides a hydrostatic skeleton.
body is segmented which increases locomotion by permitting the independent movement of the separate segments more complex nervous system coelom is fluid filled and divided internally by septae and serves as a hydrostatic skeleton that provides a structure that muscles can pull on.
this causes an increase in size because each organ is repeated
cephalization: head prostomium+peristomium tentacles and palps as sensory structures peristomium contains mouth, pharynx chitinous jaws. organs well developed into definite system, nervous, circulatory, excretory systems segmentally arranged. closed circulatory system hermaphroditic with sexual reproduction complete digestive tract. with respiratory pigments. excretory ciliated funnel collects waste from coelom and transports it to nephridia.
single layer of cells that secrete thin flexible cuticle and setae: chitinous bristles repeated used as anchors.
2layer of circ and long muscle layers. body cavity lined with peritoneum forming mesenteries that hold blood vessels and the septae between segments
burrow using setae
waves of peristaltic contraction 1 contraction of circular muscles the animal elongates animals shortens as longitudinal muscles contract setae anchor end of body while front end pushes forward.
crawl: polychaetes uses parapodia to move
swimming: polychaete and leeches use undulating movements.
might resemble centipede because of setae and parapodia that resemble legs.
many setae largest most diverse,
deposit feeders, filterfeeders predators parapodia to crawl no clitellum sensory tentacles and eyes use parapodia paired appendage for respiration. no permanent gonads adults produce gametes in temporary swellings. external fertilization with trochophore ciliated larva.
no parapodia, have clitellum setae reduced or absent, hermaphrodite with permanent gonads. scavengers, burrow breath through skin. clitellum: glandular epidermal area that secretes mucuous to hold 2 mating individuals together transfer of sperm and secrete a cocoon for embryo to develop and secretes albumin for developing embryo in the cocoon
sub class Hirudinea
dorsoventrally flattened, parasites, no septa coelom filled with connective tissues acts as a secondary circulatory system no parapodia poor hydrostatic skeleton use muscle layer for undulating swimming movements.
defining characteristics paired lateral sensory organs amphids on the head derived from cilia and opening to outside through a small pore. triploblastic, syncytial epidermis.
unsegmented, pseudocoelomates or acoelomates widespread and abundant in all habitats some parasites
difficult to identify because of their small size, no visible structures, tapered at both ends. covered by thick multi layered cuticle that is noncellular collagen secreted by the underlying epidermis. recycle nutrients, decompose toxins and wastes no cilia. gas exchange through the sin because the cuticle is permeable
organs not enveloped by peritoneum, pseudocoel fluid when present serves as circulatory medium but not waterproof so must be in water or thin film of water the thick cuticle protects parasites from host digestive enzymes and abrasion in soil sediment
cell number is constant increase in size of individual size
no circ muscle only longitudinal muscles.
fluid filled pseudocoelom important as a transport medium of oxygen food wastes
pressure created by tough cuticle and muscle layer
creates a hydrostatic skeleton, no peristatic waves, no cilia so move by undulating the body into sinusoidal waves through alternating contraction of long. muscles. need substrate to provide resistance against which animals can generate thrust muscle controlled by simple nervous system. nerve ring ganglia and long nerve cord.
complete digestive system
pharynx produces a suction to draw food, highly muscular pharynx to prevent the high pressure of surrounding pseudocoel to collapse the non reinforced digestive tract, extracellular digestion and nutrients are absorbed by one cell thick intestine.
series of canals or tubules or interconnected glandular cells, renette cells or protonephridia tubule and empties through excretory pore
no circulatory or respiratory system.
exhibit complex behavior and dioecious amoeboid sperm internal ferilzation. parthenogenesis lack free living swimming larva stage. protostome
dauer larva: state of developmental arrest until environmental conditions improve
parasitic nematode: packed in their prefered tissues in host block the flow of nutrients or fluids through their mouth part diversity can feed on different things
because they produce a characteristic infective stage called a microfillaria. extensive migration within definitve host
predators, parasite, burrow large diversity of feeding lifestyle
what makes nematodes good parasites
cuticle non living smooth no antigens
internal fertilization and resistant eggs
as well as small size
chemical diversity to avoid host immune system
synapomorphies: mantle, radula, osphradium, ctenidium
well developed head except bivalves that bears sense organs
soft bodies covered by a calcareous shell.
advantages of having a true coelom
a body cavity that is completely lined with mesoderm that can develop into muscle layers and internal skeletal elements alarge fluid filled coelom surrounded by muscle layers makes for amore effective hydrostatic skeleton leads to development of a more complex circulatory system, better blood supply to all internal organs. since mesoderm lines the digestive tract this allows for development of much more complex and elaborate digestive organs with mesenteries to support internal organs.
most versatile body plan
mantle secretes shell or becomes outer body covering, shell internal or external
radula: specialized feeeding organ in mouth
foot: usually used for locomotion
osphradium: sensory organ lateral nerve cords connect to olfactory ganglion contacts water before it enters the gill to monitor water quality and detect prey
bivalve missing radula
contains internal organs including a highly specialized digestive tract paired kidneys and reproductive organs located above the foot.
envelope or heavy fold of tissue covering the visceral mass outer layer of the epidermis often contains sense organs, secretes the shell. overhangs the visceral mass to form a mantle cavity which often contains the gills or serves itself as a respiratory organ.
is reduced to an open space around the heart and becomes part of an open circulatory system except cephalopoda.
products of digestive, excretory , reproductive system
empty into mantle cavity before release by a continous current of water created by cilia to bring in food and oxygen and to remove wastes and gametes and some are able to retract head or foot into mantle cavity for protection
mantle secretes a shell made up of calcium carbonate which serves as a protective exoskeleton or used shell by bivalves to rasp into wood or rock in some such as squid and octopus the shell is internal and greatly reduced and the mantle serves as the animals outercovering
in mouth tongue like rasping organ supported by odontophore a cartilage like rod used to scrape pierce tear or cut food also act as a conveyor belt to move food toward the digestive tract containing row of teeth used to obtain and grind food
broad flat muscular organ adapted for locomotion a specialized part of the ventral body wall snails use it for creeping over surfaces, clams use it plow through the mud squids use it seizing prey or for attachment and in some a portion of the foot is modified into a long tubular proboscis for feeding
detritus, filterfeeders, grazers, carnivores. complete digestive tract divided into discrete functionally specialized regions
folded ciliated gills, ctenidia: thin feathery sheets of tissue covered with cilia also used for feeding in bivalves some molluscs breath through their skin or some the mantle is modified into a respiratory organ
well developed with 1 pair of nephridia metanephridia a tube that opens into a body cavity at one end and drains to the outside. in many the nephridial tubule also acts as a gonoduct. and in some excretion occurs through the body wall and gills
trochophore larva found in annelids and flatworms
some gastropods and bivalves produce a second veliger larval form some bivalves produce a parasitic larva glochidum
development is direct in cephalopods many freshwater snails and some bivalves
mussels, clams, scallops, oysters all aquatic
msot filter feeders, no head no radula almost no cephalization shell laterally compressed consist of 3 valves. shell used for protection burrowing propulsion shell secreted by mantle produce pearls protective action toward some foreign body between shell and mantle
posterior portions of mantle come together to form incurrent and excurrent siphons,
use foot for locomotion
changes in blood pressure as hydrostatic skeleton allow foot to dig in an anchor itself in sediment some are sessile and attach to substrate by byssal threads secreted by glands in the foot.
most are filter feeders
gills used to filter food, strain food as water passed over giles, trapped in mucuous and moved by cilia to mouth
some deposit feeders: use long proboscis lie organ formed from modified foot to collect food in sand or mud.
some use shell to extract food.
some are predators or symbiotic algae
complete digestive system
gills used for respiration cilia on gills create incurrent and excurrent flows oxygen extracted from water passing over gills.
dioecious external fertilization gamates discharged into mantle cavity trochophore larva and some have second veliger larval form.
largest and most succesul class of molluscs
diverse marine freshwater terresterial distinct head with cephalization that contain sense organs andmouth. simple eyes, tentacles, chemical receptors
mouth with radula
elongated body with foot below for gliding
mantle secretes shell and forms dorsal surface of animal
shells with operculum
with degree of coiling. tortion a separate evolutionary event animals begins with basic bilateral symmetry but becomes asymmetrical brings gills up for better gas exchange and makes more room in shell for retraction but it puts anus over head greater change of fouling mouth some shells show spiral winding instead makes more compact but unbalanced reduce fouling of torsion
wide variety of feeding
herbivores use radula to scrap algae off hard surfaces filter feeders. scavengers, carnivores can use long proboscis for predation use ctenidia in aquatic forms terrestrial lack gill but have a have a highly vascularized mantle cavity that serves as a breathing lung with pnemostome. nephridium to remove metabolic wastes
dioecious external and internal fertilzation
squid, octopus, cuttlefish
all marine andmost active. only nautilus has external shell but spiral but divided into chambers connected by cord of living tissue siphuncle can adjust gas in chambers for neutral buoyancy.
some have internal shell completely enclosed by mantle
mantle encloses and protects animal
shell sacrificed for speed to avoid predation
can forcefully expel water from the mantle cavity
through a ventral funnel ( siphon)_ creating a jet propulsion the funnel can be pointed to quickly move in any direction. some have lateral fins that greatly improve swimming ability. surface of animal covered by chromatophores elastic pigments surrounded by tiny muscles change color head is undistinguishable from foot. head foot elongated into 8-10 tentacles and 1 longer arms
mouth at center of arms
contain chitinous beak or jaws. octopus beter adapted to crawling suing suction disks on tentacles all are predators use tentacles and arms to capture prey and handle prey strong beakline jaws enclose tongue like radula octopus and cuttle fish have poison glands to help subdue fish.
more active so require more oxygen, large pair of gils
no cilia mantle cavity expands and contracts to draw water over gills, 1 way valves allow water to enter along edges of mantle but force water through funnel for locomotion. closed circulatory system more efficient gas exchange and transport nervous system larges of all invertebrates
sensory organs better developed eyes statocysts tentacles inksac for protection
dioecious males often make color displays sperm enclosed in packets spermatophores and stored in mantle cavity arm of male is used to transfer sperm to female direct development. plucks spermatophore from its own mantle cavity and inserts into females mantle cavity.
bilateral, triploblastic, protstome, crabs, crawfish shrimp centipedes insects
more widely distributed live in virtually every habitat, dominant animals
jointed les: jointed appendages that can be modifired in anumber of ways to form antennae, mouthparts, reprodutive organs most with head thorax abdomen
hard exoskeleton made of chitin completely covers body excellent for protection and waterproof good for life on land
segmented body allows for infinite possibilities for adaptive modification
well developed head with numerous sense organs
first animals to move to land and to fly
thicker than flexible chitin of previous animal phyla because it is hardened with proteins and calcium deposit. secreted by the epidermis but animals cant grow without shedding and regrowing a new exoskeleton ecdysis: envt cues and a buildup of pressure in the body sheds old cuticle triggers hormones that triggers epidermis to secrete enzymes. that digest and dissolve inner layers of old cuticles and it separates from body wall animal is vulnerable during this time animal inflates itself and allows new cuticle to harder
comlex muscular system
the jointed plates of the body and legs provide attachment point for muscles layers of muscle surround internal organs
feeding and digestion
carnivores, herbivores omnivores, parasites 4-6 pairs of feeding appendages near their mouth. two main types of feeding appendages.
chelicerae: pinchers or fans: mandibles jaw like with numerous accessory structures with a well developed complete digestive tract with grinding and storing and absorbing foods.
need some kind of respiratory system since waxy cuticle is impermeable. gills in aquatic species, thin feathery structures or flat sheets of tissue, book gills in some chelicerates extend to form abdomen, lungs protected chambers for air breathing arthropods their walls of chamber allow exchange of gasses with body fluids
book lungs: several hollow internal folds
trachia: branching tubules that delivers oxygen directly to tissues preadaptation to flight because oxygen doesnt need to travel in blood allows for high metabolism doesnt limit body size.
open circulatory system
coelom becomes reduced haemocoel filled with blood dorsal heart and blood vessels with pigments to carry oxygen.
nervous system similar to annelids
dorsal brain and double nerve cord with paired ganglia in each segment. developed sense organs simple eyes compound eyes. second only to cephalopods in complexity this allows for more complex invertebrate behaviours.
remove excretory wastes and prevent excessive water loss antennal glands at the base of antennae in crustaceans regulate salt balance
malpighian tubules; unique to arachnids and hexapods collects salts and wastes and drains into the intestines.
coxal glands: modified nephridia at base of legs in some chelicerates in some aquatic species nitrogen wastes are excreted through skin or through gills
variation in development stages some undergo direct development or indirect with metamorphosis. some aquatic species forms with free swimming nauplius larva a few reproduce parthenogenetically.
arthropods vs annelids
similar nervous sustem
metamerism with tendency for segments to become specialized
some have same type of excretoy system
spiral cleavage in primitive members
mesoderm derived from 4d blastomere
difference: arthropods have hardened exoskeleton undergo ecdysis loss of coelom and evolution of haemocoel open circulatory system and heart and ostia in each segment and eggs are centrolecithal.
continuous increase in size because they molt through life, bioluminiscent, colorful, aquatic, marine, benthic some are sessile base of aquatic food chains. gills for breathing, 2 pairs of antennae, one pair of mandibles and their appendages modified for functions.
body plan of crustaceans
cephalothorax, abdomen tail
carapace extending oversides of animal
segmentation most apparent in abdoment'
many parie of appendages with most being biramous modified for availability of uses swimming walking defense feeding respiration
decapods ( crayfish, bras, lobster)
1st 2 pair antennae with chemosreceptors
next 5 pair feeding appendages with 1 pair of manible 2 pair of maxilla 3 pair of maxillipeds next 5 are walking legs and gills next 5 are swimmerets used to carry eggs and acts as a copulatory organ, last uropod swim fin
use mandibles, maxillae and maxillipeds
predators use claws to break open shells
suspension feeders barnacles use legs to strain water for food. scavengers, isopods,
complete digestive system.
cardiac stomach with gastric mill for grinding
pyloric stomach for sorting digestive gland secretes digestive enzymes
in small crustacean occur across body surface in larger crustaceans respiration usually by feathery gills on bases of walking legs, in some sides of carapace form gill chambers that enclose gills have an appendage called a lauer that creates a water current across gills.
bear mandibles, maxillae and 2 pairs of antennae
superclass myriapoda: chilopoda, diplopoda
Subphylum Chelicerata lack jaws
class arachnida : spiders, scorpions and mites
superclass merostomata: horseshoe crab
adaptation to land
waxy cuticle impermeable to water
improved excetory system for salt and water balance
conserve water by getting of N wastes as urea or uric acid rather than ammonia
respiratory system to extract oxygen directly from air instead of water
moist thin surface protected inside body
modification of appendages
strong muscles strong support
internal fertlization so gametes remain moist leads to anatomical changes for copulation more elaborate courtship rituals eggs must be protected from drying and contain enough nutrients for early development and changes in behavior to become inactive during temperature extremes.
head fused with thorax, cephalothorax. chelicerae to grab pierce tear prey most also have a second feeding appendage pedipalp no antennae 4 pairs of walking legs.
book gills- aquatic
terrestrial use book lungs or trachae
excretory organ malpighian tubules have coxal glands at base of some legs, dioecious some with elaborate mating rituals some with considerable parental care.
body divided into three regions head bears sense organs andmouth parts thorax 3 pairs of legs and 1 or 2 pairs of wings abdomen contains most internal organs.
exoskeleton made of chitin molt to grow vulnerable to predators air breathing and respire by trachea through holes in body called spiracles. sexes are dioecious simple and compound eyes
feed on plant juices and tissues, leaves flowers predators parasitic the same basic mouthparts that are modified to facilitate different methods of feeding.
change in shape and form that some animals undergo during development not restricted to insects complete digestive system with excretory
long worm like segmented body divided into head and trunk head with 1 pair of antennae and poorly developed clusters of ocelli with paired appedanges in all segments. terrestrial moist mandibles for feeding, insect like trachae for respiration insect like malpighian tubules for excretion centipedes body flat in cross section 1 piar of walking legs onmost segments predators with pairs of poison fangs
millipedes round in c ross section 2 pairs of legs scavengers
Deuterostomes triploblastic, bilaterial as larvae, coelomate: anus develops first from blastopore all marine unable to osmoregulate almost all are bottom dwellers, a few are pelagic swimmers a few are commensal.
most with pentamerous radial symmetry as adults
no cephalization- oral vs aboral surface
endoskeleton of calcium plates
unique water vascular system for feeding and movement
dermal branchiae for gas exchange
no real circulatory system
sense organs are poorly developed
pedicellariae for protection
is an adaptation for a sessile existence
water vascular system
internal fluid canals tube feet form external extensions of w.v.s
in many classes ossicles have body projections for defense
they can vary rigidity of dermis. under dermis under nervous control allows animals to hold various postures for long periods without muscular effort. circ and long muscles
true coelom lined with peritoneum
w.v.s a second separate coelomic compartment, derived from coelom and lined with ciliated epithelium operates hydraulically filled with sea water, some proteins and some cells. internal canals connect to the outside through madreporite-stone canal- ring canal- long radial canals leads to smallmuscular scas that serve as fluid ampullae connected to muscular tube feet that can stong force cling to substrates muscles used o move tube feet w.v.s compensates for the absence of well developed a blood circulatory system
particle feeders, scavengers or prefators. stomach 2 chambers cardiac and pyloric and digestive enzymes are secreted into stomach by pyloric caecae feed on small pkankton and organic debris mucuos strands carry food to the mouth, carnivores feed onmolluscs, crustaceans polychaetes and other echinoderms, uuse chemoreceptors to detect and locate prey.
dermal branchae : exchange of resp gasses and get rid of N wastes same functions are also showed by tube feet in most groups
Class Asteroidea sea stars starfish
body composed of rays projecting from a central disc arms not sharply set off from central disc in some arms are very short mouth and tube feet underneath pentamerous surface.
sexual dioecious gonads insmall area at base of arms free swimming bipinnaria larva metamorphosis converts bilateral larva into radial juvenile.
Class Ophiurioidea brittle stars
have arms but long thin arms shaply set off from disk no ambulacral groove tube foot play little role inlocomotion used infeeding, locomotiona by snake like arm movement ossicles arranged into flexible columns connected by muscle strands.
Five arms articulated; distinct from body disk
Arms may be branched (basket stars) or unbranched (brittle stars)
Arms lack open ambulacral groove
Most are deposit or suspension feeders
Class Echinoidea sea urchins
Body globular or disk-shaped; lack arms
Skeletal plates fused into rigid test
Pores in test allow tube feet to exit
Protrusible jaw apparatus (Aristotle's Lantern)
Mostly herbivores or detritivores, but some predatory
Body elongated in oral-aboral axis
Secondarily bilaterally symmetric (no dorsal tube feet)
Skeleton reduced to isolated ossicles; soft-bodied
Ring of tentacles around mouth
Most are deposit feeders in soft sediments
most advanced phylum of animal kingdom, more complex anatomy nervous , circulatory but less diverse than arthropods or molluscs
notochord: flexible rodlike structure that extends the length of the body and provides the basic support and serves as main axis for muscle attachment
dorsal hollow nerve cor: in most invert groups nerve cord is ventral and paired with paired ganglia along its length in chordates is a single dorsal hollow never cord front end usually enlarged to form brain
pharyngeal slits: slit like openings leading from throat to ourside first as filter feeding apparatus in orther as gills in some found in embryo and lost as adults
post anail tail in aquatic chordates provides motility in terrestrial a tail for leverange and balance
Urochordata( tunicates and salp)
all marine, bag like sessile suspension feeders as adults often colonial attached to a hard substrate lack some of the major characteristics of the phylum adults resemble sponges lack a coelom pump water through siphones but tadpole like larva has typical chordata features aflts have tought non living tunic covering body secreted by mantle, complete digestive tract pharynx serves as resp organ
open circulatory system nervous system nerve with ganglia and plexus of nerve filers excretion no specialized excretory organs hermaphrodites larva reveals true chordata nature once attached larva undergoes and exceptionally rapid metamorphosis into the adult
Subphylum Cephalochordata (lancelets0
intermediate characteristcs between invertebrates and vertebrates. adult animal has all major characteristics. burrowers and swimmers slender translucent laterally compressed body myomeres with muscles for swimming hollow dorsal nerve cord filter feeders closed circulatory system respiration occurs through the pharynx but gas exchange occurs by diffusion through ventral body wall. notochord almost no cephalization simple excretory system of nephridia similar to those in annelids dioecious, cilia used for swimming and drawing food retain chordate features as adults