Vertebrates 1 - Fish

4 elements that help fish get bigger faster stronger

Get more oxygen – gills, heart,

Get that skeleton on the inside,

Jaws!!!!,

Paired fins

Pharyngeal slits aka gill slits

**key innovation of deuterastome ancestors

pouches on lateral surface of head

ancestral trait of deuterostomes but lost in echindoderms

used in filter feeding

parayngeal arches structure

support gills/respritory surface

made out of bone (in fish) and sometimes chartiledge

pharyngeal arches evolutionary signifigance

found in vertebrates…evolved many functions including hyoid apperatus (bones in human mouth/upper respritory system)

ancestral traits of chordates

dorsal hollow nerve chord, notochord, muscular post anal tail

synamorphy

shared derived characteristics that are unique to a particular clade, indicating a common ancestry

charecteristics of vertebrates

axial skeleton, appendicular skeleton, closed circulatory system with ventral heart, organs suspended in coelom

axial skeleton

• cranium (skull)

• vertebral column (spine)

• ribs

appendicular skeleton 

pectoral and pevlic girdle *think pectoral and pelvis bones (fins in fish)

Boney Fish & Gill Slits

have 4 gill slits

Each arch has pairs of gill filaments

Bony fishes also have a gill cover (operculum)

Gill Filiment Structure

thin, vascularized (has vessels or capilary beds that are one cell thick), high surface area

Counter current exchange

water flows in while opperculum closed…creates pressure difference, opperculum open and water flows out through flimaments with blood flowing in opposite direction…lamellae take in o2 though this counter current exchange and blood becomes oxygenated

fish circulatory system

*key innovation

closed system, single curcuit… heart pumps blood to gills, then oxygenated blood goes through body to be use then back to heart to get reoxygenated

fish two chamber heart

sinus venosus pumps into atruim, then to ventricle, then pumped out to bulbus arteriorus…arteries and viens buldge

Jawless Fish Traits - who are they and what do they not have

*vertebrates but not gnathostomes

• no jaw and no paired fins an no swimbladder

Hagfish (mixinodiea)

scavengers

used for leather products

don’t regulate osmotic concentration (salt)

knot tying - use to pull and suck food

mucous production

Lamprey (Petromyzontoidea)

oral disc to latch onto prey - parasitic to fish

larval stage: ammocete

invasive and got into great lakes

Evolution of Jaws

begins in gnathastoma

evolved from anterior gill arches

teeth evolved from scales in mouth

greatly improved ability to feed and

diversify

Evolution of Paired Fins

Gnathostomes innovation

on pectoral and pelvic limb girdles

enabled more active swimming

used for steering, stabilizing, and

lift

either undulate or ossiliate

Chondrichthyes (cartilaginous fishes) - Gnathostomes p1

sharks, skates, rays

mostly marine

no swim bladder

predators, scavengers,

filter-feeders

Shark diversity

high diversity (small and big)