BIO 202 Chordata 1 - Exam 4

what phylum has the least constraint of body plan

phylum chordata

two invertebrate subphyla of phylum chordata

cephalochordata and urochordata

what developmental patterns does phylum chordata have

deuterstome

what two phyla are chordates related to

echinoderms and hemichordates

what date did phylum chordata originate

precambrian origin with rapid diversification in the paleozoic

5 distinctive features of phylum chordata

notochord, hollow dorsal nerve cord, pharyngeal gill slits, endostyle, postanal tail

notochord

endoskeleton for muscles; lost or replaced in some

hollow dorsal nerve cord

controls muscles, includes brain; lost or replaced in some

pharyngeal gill slits

open to outside; respiration and feeding; become other structures in vertebrates

endostyle

generates mucus for feeding; thyroid gland in vertebrates

subphylum cephalochordata

our primitive cousins; consists of lancelets or “amphioxus”; “little fish without heads”; all 5 chordate features present

how do cephalochordata feed

filter feeds by passing water over pharyngeal slits covered in mucus; enters though gill slits to the atrium and out the atriopore

circulatory system for subphylum cephalochordata

closed blood vascular system; no heart (peristalsis of vessels); no blood pigments or cells

reproductive system for subphylum cephalochordata

simple gonads; gametes shed directly into atrium and out atriopore

subphylum urochordata

our veyr weird cousins; loss of all chordate structures

two classes we need to know for subphylum urochordata

class ascidiacea (sea squirts) and class appenduclaria (planktonic)

class ascidiacea

sea squirts; solitary and colonial as adults; tadpole larva has 5 chordate features; filter feed; when colonial, they are zooids

class appendicularia

abandoned houses major source of marine snow; important for global carbon cycling

post-anal tail

propulsion, often with fins; vestigial in humans (coccyx)

subphylum vertebrata of phylum chordata

has vertebral column, cranium, endoskeleton, neural crest

vertebral column

notochord replaced by column of interlocking vertebrae

cranium

protective housing around the brain

endoskeleton

grows with body; cartilage, then-bone

neural crest

embryonic cells, contribute to development of cranium

5 extant classes of subphylum vertebrata

myxini, petromyzontida, chondrichthyes, actinopterygii, sarcopterygii

myxini

hagfishes; marine scavengers; have slime glands to make sheets of mucus

petromyzontida

lampreys; marine and freshwater

chondrichthyes

sharks, skates, chimaeras; mostly predators; most are marine; no swim bladder

actinopterygii

ray-finned fishes

sarcopterygii

lobe-finned fishes

how did the evolution of the endoskeleton progress

notochord to vertebral column, cartilage to bone

how did the evolution of the pharynx progress

pharyngeal slits to gills, greater respiratory capacity

how did the evolution of the nervous system progress

greater development of senses and brain

how did the evolution of the appendages progress

greater development of paired pectoral and pelvic fins

how did the evolution of the jaws progress

modified cartilaginous gill arches derives from neural crest cells with jaw muscles from gills

what do myxini lack

lack jaws, scales, paired fins, bone, and vertebral column

what are teeth of myxini made of and used for

made of keratin on tongue; used for rasping food

what do petromyzontida lack

lack jaws, scales, paired fins, and bone

what are teeth of petromyzontida made of and used for

made of keratin around sucker-like mouth; may be used to parasitize

what does the life cycle involve for class petromyzontida

involves ammocoetes larva that filter-feeds and looks like a cephalochordate (lancelet)

what do chondrichthyes have

have jaws, paired pelvic and pectoral fins, placoid scales adapted to form teeth

what kind of skeleton do chondrichthyes have

cartilaginous skeleton

how do chondrichthyes maintain balance between water and salt

osmoregulation; requires copulation and shelled eggs

what does class actinopterygii have

have jaws, paired pelvic and pectoral fins, light-weight cycloid, ctenoid or ganoid scales, swim bladder

what kind of skeleton does actinopterygii have

bony skeleton (endochondral); gills are covered by bony operculum

what does osmoregulation support in actinopterygii

permits free-spawning and planktonic development

what does class sarcopterygii have

have jaws, paired pelvic and pectoral fins, heavy enameled scales

what kind of skeleton does sarcopterygii have

bony skeleton

what does the swim bladder do in sarcopterygii

acts as a lung in lungfishes

what did sarcopterygii give rise to

tetrapods

what do sarcopterygii look like

they look like the “living fossil” Coelocanth, a mesozoic relic