Jawless-jawed and life in the water Flashcards

Question

jaws and teeth: features

Answer 1

- most likely evolved separately - teeth came from denticles already existing in some shape/form as seen on todays shark skin - placoderms (earliest jawed vert had jaw, no teeth)

Answer 2

- ancestral situation where teeth form in skin - rest on jaw bone - new teeth roll forward in a whorl to replace old teeth

Answer 3

- teeth embedded into jawbone - ancestral form: like pleurodont where teeth set in shelf on inner side of jawbone - also seen in modern amphibians

Answer 4

- teeth fastened to top of ridge, absence of socket | - most common in teleosts

Answer 5

- teeth fastened in sockets and held in place by ligs | - most common mammals

Answer 6

- assoc w existing branchiomeric mm - allows animals form strong suction action - for ventilating gills - also suck in prey

Answer 7

- dev more complex vert through time - ossified dorsal arches, protect nn cord (neural arch), - matching pair on ventral side (hemal arch)

Answer 8

- notochord more less replaced by series of well dev vert acting as scaffolding for axial mm

Answer 9

- vertebral centrum/and or central elements which ribs articulate

Answer 10

- all sorts of spines | - interlocking processes unlike ancestral vert

Answer 11

- gnathostome invention - offer further scaffolding upon axial mm: better locomotion - axial mm clearly arranged into ep/hypaxial segments divided by horizontal septum - middle of mm pack, lateral line collects vibration info (sent to ear) - 3rd semicircular canal allow movement and orientation in 3D space

Answer 12

- well dev brain - cerebellum - olfactory tracts - lack 3rd semicircular canal

Answer 13

- evolved myelin sheaths - increase efficiency of NS - 3 semicircular canals - conus arteriosus in heart: elastic reservoir to maintain uni-directional high pressure pumping sys - specialised duct connecting gonads to cloaca, for sperm/egg

Answer 14

- guidance sys in 3D - unpaired fins of midline: control roll and yaw - pectoral, pelvic fins: control pitch, and breaks - caudal fin: increase SA of tail, more thrust

Answer 15

- connection from pectoral fins (in sharks) | - three elements of fin articulating w girdle

Answer 16

- ancestral vert had both int/ext arches - alternatively lost in cyclostomes and gnathostomes - morphological changes due to changing timing of dev genes

Answer 17

- likely gill arches evolved to enhance fill ventilation | - changes co-opted to perform new functions as jaws

Answer 18

- once produce powerful suction for gill ventilation, easy for using to forage - first arch must be articulated so open/close mouth - hyper/branchial mm dev to help power opening/closing -added stress so arch stronger, second gill recruited for structural support

Answer 19

- vert jaw derived from branchial arches historically assoc w gills - 1st gill arch: mandibular arch - 2nd: hyoid arch (supports 1st) - those post arches: support gills - most vert no hole btw 1st/2nd, some present as spherical in sharks/fish

Answer 20

still exists: - sharks, - bony fish extinct: - placoderms - acanthodians

Answer 21

- large and diverse group - paraphyletic - grouped based on morphology - some more primitive/ more recently derived taxa in group

Answer 22

- traditionally grouped w bony fish, molecular evidence suggests not group at all

Answer 23

- covered in bony plates, typically ant end - distinct set head plates linked via joint to rest of body: head can move independently - endoskeleton mineralised on edges only (perichondral) vs bony fish complete ossification (endochondral) - during Devonian times, dom and most diverse vert - some 8m length - majority wiped out by later Devonian event

Answer 24

- most lacked true teeth, modified dermal plates projecting from jawbones - later species evolved true teeth - not much known about soft bits, evidence in Aus: - myomeres weakly W shaped, lack clear distinctions btw epaxial and hypaxial sections - some: internal fertilisation, modified anal fins resembling male sharks - also may had embryos inside specimen

Answer 25

- named after strong spines assoc w fins - probs not single clade, dist all over gnathostome heritage - most diverse during Devonian period in freshwater (started out as marine group) - fusiform caudal fin suggest midwater taxa - some species 2+ paired fins: pectoral, anal - wide diversity of lifestyles, some w teeth also had whorls similar to sharks

Answer 26

- gravity insig in water vs. huge effect on terrestial vert - low viscosity of air: wind resistence neglible, but in water good hydrodynamics is vital - 800x denser than air - 55x more viscous than air - 40x less O2 - water conducts heat 25x faster than air

Answer 27

- much harder to extract from water - need to pass over gills w high SA - by buccal pumping, ram ventilation - blood vessels in gills arranged to max uptake: - deoxy blood flows one direction, fully oxy water opp direction - counter current= O2 diffusion gradient maximised from water to blood

Answer 28

- fish effectively made of water, neutral buoyant (no effort to maintain position in water column) - bony fish: swim bladder on doral side wedged btw vert column/ peritoneal cavity (body vol- 5% marine teleosts, 7% freshwater teleosts)

Answer 29

- to swim up/down water column, need to adjust pressure - primitive fish: valve connecting stomach to burp air out/ gulp air and force back in - more derived fish: changes in vol by secreting gas from blood v into/out of swim bladder

Answer 30

- have link btw swim bladder and gut - more primitive fish - eg. trout

Answer 31

- despite diff of primitive/more derived fish - both have this aka gas gland - enable excretion of O2 into swim bladder even at incredible depths - coz pressure in deep sea, rete mirabile have to be v long to overcome gradient

Answer 32

- no connection btw swim bladder and gut | - more derived fish

Answer 33

- light/ colour - mechanical disturbance - chemical cues

Answer 34

- water rapidly absorbs light - red hardly penetrates, most colours lost in first 100m of water - only blue light persists afterwards - surface fish nearly all tetrachromatic, spherical lens coz refractive index of water - other fish, vision waste so depend on other senses

Answer 35

- works v well underwater - most bony fish has well dev lateral line - neuromasts detect displacement of water - also hav typical vert internal ear, for orientation and hearing

Answer 36

- spread nicely underwater - already in solution - many fish sense chemicals 1 part/ billion

Answer 37

- also works well as water conducts electricity - electrosensitivity likely ancient vert trait - some fish: electrocytes (modified mm cells) generate electricity to stun prey, communicate or navigate - eg. weak electric fishes

Answer 38

- network (ampullae of Lorenzini) on head - hone electrical discharge from mm and nn activity of prey - also picks up earths magnetic field

Answer 39

- pre good electrosensitivity for foraging | - may evolved independently

Answer 40

- srs issue for all vert esp aquatic ones to control ions - skin highly permeable (not equally to everything) - vert control water/ion balance by actively/passively passing molecules from inside/outside vice versa - also deal w waste (ammonia) toxic product of protein decay - kidneys play huge role in both

Answer 41

- fundamental unit is nephron - millions in kidney producing urine - extracts foreign substances and waste products from blood - control salt and water balance

Answer 42

- structure unique to vert | - arteriole under pressure leaks ultrafiltrate into bowmans capsule

Answer 43

- don't achieve iron conc. diff from env =isotonic to sea water - other vert hav lower salt conc. - 1. salt move into marine vert - 2. water tries to leave - cartilaginous fish counteract by having high urea lvls in blood - opp for freshwater fish

Answer 44

- fish that remain in either salt/fresh water entire lives | - thus fixed physiology

Answer 45

- move btw fresh/salt water | - more complicated physiology

Answer 46

- keep as much water as possible, excrete excess ions - marine teleosts drink alot of seawater and pump ions across stomach into blood to encourage water follow - gills pump Cl- out and Na follows - small glomeruli, lack distal convoluted tubule - produce lil but highly conc. urine

Answer 47

- sharks - high urea to prevent salt in, like coelacanths - water actively flows across gill membranes - sharks don't need to drink - plenty of water, glomeruli large, great filtration rates - ions follow water across gills but unlike marine teleosts, membranes relatively impermeable to ions - excess salt secreted by rectal gland

Answer 48

- salt tries to escape, water coming in - teleosts reasonably impermeable skin - huge water across gills to breathe - both amphibians and fish produce huge vol urine, kidneys overtime to extract excess water from blood - nephrons actively pump ions back into bloodstream from ultrafiltrate - fish also hav Cl- ion pumps in gills to actively move Cl from water to blood - causes diffusion grad and Na travels across passively

Answer 49

skin, gills, urine

Jawless-jawed and life in the water Flashcards

(87 cards)