Deuterostomes PART THREE

key features of myxiniformes (hagifish)?

elongate, no paired fins, cartilagionous skeleton

what are hagfish teeth composed of?

keratin

hagfish body gluid relationship with seaweed?

iso-osmotic (having the same osmotic pressure as another solution)

hagfsh feeding strategy?

marine scavengers

key features of petromyzontiformes (lampreys)

elongate, no paired fins, cartilagionous skeleton, both parasitic and non

lamprey feeding technique?

filter-feeding larvae (ammocoete)

what are the lamprey families?

geotriidae (southern lmpry), mordaciidae (southern topeyed lmpry), petromyzonidae (northern lmpr)

when did ostracoderms first appear?

ordovician era, around 480 mya

ostracoderms key features?

externally armoured with bony plates that show evidence of sensory canals and gill openings, fresh-water (possibly osmoregulators), jawless (some bony mouth plates)

ostracoderms fins?

origins of paired (pectoal) fins, typically heterocercal caudal fish

purpose of ostracoderm armour

defensive, sensort, electrosensor insulation, mineral storage (Ca, P)

function of jaws

active predation, manipulate food, herbivory, mating, improved (forceful) gill ventilation

where are jaws thought to have evolved from?

anterior gill arches, where the first two moved foward to become them

when did the placoderms first appear?

early silurian period, around 440 mya

what fins did placoderms have?

pectoral, pelvic

placoderm key features?

jaws, toothless, head-trunk joint, primarily benthic

what group are vertebrates found in?

jawless fish (agnatha)

what groups are gnathostomes found in?

actinopterygians (ray-finned), sarcopterygians (lobe-finned), chondrichthyans (cartilaginous_

which group are chondrichthyes found in?

chondrichthyans

subclasses of chondrichthyes?

holocephalii, elasmobranchii

what organisms are found in holocephalli?

chimeras, ratfish, few deepwater species

what organisms are found in elasmobranchii?

sharks, skates, rays, fairly widepsread

why is the holocephalans jaw strcuture unique

upper jaw fused to braincase

key features of holocephalans?

cartilaginous skeleton, modified pelvic fins (into intromittent organs or claspers), direct development (no larval stage), oily liver, operculum, modified teeth (crushing plates)

what groups are osteichthyes found in?

actinopterygians (ray-finned), sarcopterygians (lobe-finned)

what groups are actinopterygii found in?

actinopterygians (ray-finned)

characteristic of a actinopterygii (ray-finned fish) fin?

fin supported by cartilaginous or bony rays, moved by muscles in the body of the fish

characteristic of a sarcopterygii (lobe-finned fish) fin?

fin supported by a series of bones, moved by muscles within the fin itself

what organisms are in the cladistia subclass (ray-finned fish)

bichirs and reedfish (14sps)

what organisms are in the chondrostei subclass (ray-finned fish)

sturgeon and paddlefish (acipenseriformes) - two families (acipenseridae and polyodontidae)

characteristics of acipenserifromes (sturgeon and paddle fish)

skeleton only partially ossified, electrosense present, heterocercal tail and lots of genome duplications

what organisms are in the holostei group (ray-finned fish)

gars (lepisosteiformes), and bowfin (amiiformes)

characteristics of holostei

ganoid scales, heteroceral tails, extensive fossil record (few extant species)

characteristics of teleostei (bony fish)

light bodies, homoceral tails, diverse body forms, generally active (fast swimmers)

what groups are sarcopterygii found in?

lobe-finned fish (sacropterygians)

families of sarcopterygii (lungfish)

lepidosirenidae, neoceratodontidae, protopteridae