8: chordate phylogeny (up to amphibians-vertebrates)

subphylum cephalochordata are…

lancelets

what key chordate features do lancelets have?

all

how do lancelets filter feed ?

they burrow tail in and cilia draw seawater into lancelet’s mouth

where does gas exchange occur in lancelets ?

across the external body surface

what is a scientific name example of a cephalocordate?

Branchiostoma

subphylum urochordata

tunicates/ sea squirts

how do tunicates feed ?

suspension-feeds w/pharyngeal sits or endostyle

a tunicate swimming larva has what key chordate features?

all

an adult tunicate (sessile) loses what key chordate features ?

it loses the notochord, postanal tail, and dorsal nerve cord

what is significant abt cyclostomes?

they’re jawless

what animals are cyclostomes?

hagfish and lamprey

what are characteristics of cyclostomes?

they are have reduced vertebrae that are undeveloped (made of cartilage), eel-like bodies,no backbone, and no lateral fins

myxini are all what kind of marine fish?

marine scavengers w/ a cartilage skull and notochord for support and movement

what are hagfish teeth made of and what’s their fxn?

keratin that aid in feeding

hagfish are famous for?

defensive slime that comes out the slime glands across their bodies

petromyzontida are what animals

lampreys

what type of fish are lampreys?

parasites w/a notochord and cartilaginous shedding

Gnathostomes get their name from the fact that…

they have jaws

where are vertebrates w/hinged jaws derived from?

skeletal rods which support gill slits

gnathostomes usually have?

bony teeth for predation

how do gnathostomes see and smell?

w/their larger forebrain

what is the name of the early jawed fish and when did it live?

a placoderm which lived during the Denoviom period (extinct)

lateral line system

organs that form a row along each side of the body that are sensitive to vibrations in surrounding water

what does the lateral line system detect?

slight pressure waves of prey/enemy

what are the 3 gnathstome fish lineages?

1. cartilagenous

2. ray-finned

3. lobe-finned

chondrichthyes all have…

skeleton of cartilage

what’s animals are the most diverse group of chondrichthyes?

sharks, rays, and skates

there is a few chondrichthyes that are?

ratfishes or chimaeras

why are bone minerals lost in chondrichthyes?

to reduce density bc buoyancy is raised by liver oils and active swimming

where do some chondrichthyes live as?

active predators in marine, as filter-feeders, and some in freshwater

how do whale sharks live as?

as a filter-feeder

what are the 3 reproductive adaptations in all vertebrates ?

they’re all w/internal fertilization

1. oviparous

2. viviparous

3. ovoviviparous

oviparous

eggs laid and hatch outside mother; embryo develops w/in protective egg-case, fed by yolk

viviparous

young develop w/in uterus; obtain nourishment prior to birth by nutrients from mothers blood through yolk sac placenta; live birth

ovoviviparous

fertilized egg retained w/in mother;embryo fed by egg yolk; live birth

osteichthyes are…

bony including ray-fin fish and lobe-finned fish

in osteichthye skeletons remain mostly…

ossified or mineralized

what reproductive adaptation do osteichthyes use?

oviparous w/external fertilization

how are osteichthyes scales like plus their fxn?

flat and slime protect and reduce drag

what are examples of fish that are osteichthyes?

actinopterygii, actinistia, and dipnoi

what is an operculum?

a gill cover

fxn of operculum

protects and helps pump water over gills

how are osteichthyes lungs modified ?

into a swim-bladder for buoyancy

swim-bladder

air sac filled w/gas helping fish float in water

a swim bladder is a lung derivative meaning…

it arose from lungs

what do ray-finned fish have?

thin fins supported by long, flexible rays modified for maneuvering & defense, lateral line, and a swim bladder

how are almost all fish finned?

ray-finned

what’s the most diverse group of all vertebrates?

ray-finned fish

how do ray-finned fish live?

in marine or freshwater as herbivores, predators, or scavengers

what percent of ray-finned fish are compromised of the living vertebrate species ?

>56%

what animals are examples of ray-finned fish?

tuna, trout, seahorse, and perch

lobe-finned fish are significant how?

they have fleshy fins called pelvic and pectoral fins supported w/bones and muscles

what are the 3 lineages of lobe-finned fish ?

coelacanths(Actinistia), lungfishes(Dipnoi), and tetrapods

coelacanths share homologous structures with…

humans (humerus)

what fish is a lobe-finned fish?

Actinistia

what animals are limbs with digits ?

tetrapods

tetrapods have how many limbs?

4 limbs w/wrist and digits which are fingers and toes

how does the neck of tetrapods move?

independent of the body

what does the pelvic girdle fused to the backbone in tetrapods permit?

forces generated by the hind legs against the ground to be transferred to the rest of the body

how do tetrapods breathe as adults ?

w/lungs having an absence of gills except in some aquatic species

why do tetrapods have ears?

to detect airborne sounds

what are ancestors of tetrapods ?

lobe-finned, lung-breathing fish w/mant tetrapod features

what is the name of fossil fish w/tetrapod features ?

Tiktaalik that could shuffle in pools and on land

what are tetrapod characteristics?

neck

ribs

fin skeleton

flat skull

eyes on top of skull

what is the basal extant tetrapod group?

amphibia

how does gas exchange occur in amphibians ?

their thin moist skin loses H2O easily and they exchange w/air across moist skin and lungs gulps air like fish to fill lungs

how do amphibians use positive pressure breathing?

they gulp air

force it down their throat

and

what reproductive adaption do amphibians use?

oviparous w/fish-like eggs that have no shells (reproduction is closely tied to fresh water since they’ll dehydrate quickly in air)

a tadpole becomes a frog by…

metamorphosis into a carnivorous adult

frogs and toads have what type of fertilization ?

external

marsupial frogs brood eggs meaning…

direct-developing larvae within a fully enclosed pouch, from which (b) froglets emerge; serves as a protected environment for embryonic development

salamanders have what body parts as an adult

4 legs and a tail

frogs have what body parts as adults ?

4 legs and no tail

caecilians have what body parts as an adult?

no legs they’re snake-like

what are the most numerous amphibians ?

frogs

salamanders are what type of terrestrial amphibians ?

moist

caecilians are what type of terrestrial amphibian?

moist burrowing