Feb 9th- 14th Flashcards
cyclostomes are ____ and consist of ___ & ____
a. Extant
b. hagfish
c. lamprey
characteristics of conodonts & ostracoderm (extinct)
- jawless
- lack bone
- single nostril
- lack paired appendages
what type of feeder are hagfish?
scavengers (feed on insides of dead or dying inverts and fish)
what are the teeth-like processes that hagfish have called?
rasp/scrape
what is the name of the slime gland that hagfish have?
integumentary glands
do hagfish have a larval stage?
no –> most likely have direct development w/o metamorphosis
the body fluid in hagfish is ____ to water
isosmotic
what is the least derived craniate lineage that still survives?
hagfish
hagfish were classified as ____ but have no ____
a. vertebrates
b. vertebrae
lamprey
rasping tongue
lack bone
ammocoete larvae
some species marine –> all spawn in FW (anadromous)
pre vertebrates –> trends in adaptation
- mechanical changes to pharynx
- encircling band of muscles
- cartilage replaced collagen of pharyngeal bars (go back to original shape after contraction
- filter feeders –> pumping allowed them to grow bigger
agnathans –> vertebrate origin
- expanded pharyngeal pumping
- deposit feeders “ mud grabbers”
- less limitation on size
- adults more benthic, larvae more pelagic
gnathostomes–> vertebrate origin
- switch in feeding methods
- raptorial feeders: pluck individual particles
- active predation permitted
- increased predation- increased size
gnathostomes–> vertebrate origin
- switch in feeding methods
- raptorial feeders: pluck individual particles
- active predation permitted
- increased predation- increased size
SUPERCLASS GNATHOSTOMATA - characteristics
- jaws
- paired appendages
- three pairs of semicircular canals of the inner ear
- notochord
- paired nostrils
- gill slits
what three lineages do gnathostomata
placoderms, elasmobranchs, teleosts
major difference between gnathostomes and agnathans
gnathostomes: jaws, agnathans: no jaws
tetrapods include..
amphibians, reptiles, birds, mammals
amniotes are
vertebrates w embryos wrapped in amnion
evolution of jaws (agnathans vs gnathostomes)
evolved from anterior gill arch
evolution of paired fins (agnathans vs gnathostomes)
evolved from paired skin flaps along the ventrolateral body wall
evolution terrestrial vertebrates (tetrapoda)
started with dactylous limbed vertebrates (have digits)
evolution of tetrapods with amnion during development
removed dependency on aquatic environment for fertilization & embryo development
evolution of amniotes with feathers (Aves)
feathers for insulation - exploited for flight
evolution of amniotes with 3 middle ear bones (mammalia)
jaw bones - vibration conduction
is osteichthyes a valid taxon?
no, grouping includes : ray-finned fishes and lobe-finned fishes
bony fish
ossification of the internal skeleton
terminal mouth
operculum (bony)
internal sac/pouch/bladder
fins strengthened by lepidotrichia
jaw specialization - improved feeding
ray-finned fishes - actinopterygii
operculum
no spiral valve
long lepidorichia- fins muscles within body
scales reduced
heterocercal tail
extensive distribution
developed olfactory system
three types of caudal fins
heterocercal
homocercal
diphycercal
heterocercal tail
vertebral column extends into upper lobe
- functionally stiffer providing lift to the posterior region of body
homocercal
Vertebral column ends with modified vertebrae that support fan-like
tail structure (internally asymmetrical) greater versatility for fine
movement
diphycercal tail
Vertebral column extends to tip without upturning.
scales
thin, flexible cycloid and ctenoid scales
scales
thin, flexible cycloid and ctenoid scales
how does shedding armor help fish?
increases mobility helping fish avoid predators and improve feeding efficiency
placoid scales
- shape is curved
- tough armor
- sandpaper texture
- same structure as a tooth
purpose of placoid scales
- decrease friction
- protection
what are the layers of cosmoid scales?
- layer of dentine like cosmine
- outer layer of vitrodentine
what are ganoid scales?
modified cosmoid scales
thick and non-overlapping
bony basal layer
what are cycloid scales?
thin and overlapping
more flexibility
grow as the fish grows
what are ctenoid scales?
- similar to cycloid scales
- with teeth at their posterior edges
- reduce hydrodynamic drag
polypteridae (Bichirs)
- lungs - air-breatheers
- continuous long dorsal fin
- diphycercal tail, ganoid scales
chondrosteans (sturgeon/paddlefish)
- lack internal ossification
fleshy finned fish
- fins at the end of short projecting appendages
- used for manuvering in water
choanae
external nostrils open internally into the mouth
4 groups of gnathostomata
- placodermi
- chondrichthyes
- osteichthyes
- tetrapoda
2 groups of osteichthyes
actinopterygii
sacropterygii
3 groups under sarcopterygii
- dipnomorpha
- actinistia
- rhipidistia
two structures connected to pharynx (evolution of terrestrial vertebrates)
- air-filled cavity functioned as a swim bladder
- paired internal nares functioned in chemoreception
what can the combination of swim bladder and internal nares be use for on land
to draw in oxygen-rich air through nares into the air-filled cavity
what were the bony elements of paired fins modified for
support and movement underwater
what did evolved adaptations to air breathing do in terrestrial vertebrates?
- increased vascularization of the air-filled cavity
- double circulation to direct deoxygenated blood into the lungs n oxygenated blood out of the lungs to the other body tissues
3 periods for the transition from water to life on land
- devion period
- carboniferous period
- Romer’s Gap
devion period
- appearance of tetrapod ancestors mass extinction event
carboniferous period
first 15 mill years tetrapod fossil evidence is lacking
Romer’s Gap
- low oxygen theory
- failed search theory
what is tikaalik?
the intermediate between fish and primitive land-living animal
tiktaalik has a ___ head and neck like ___ but ___ and ____ like fish
a. flat
b. tetrapods
c. fins
d. scales
did tiktaalik have lungs and gills?
yes
5 groupings from transition from water to life on land
- Eusthenopteron
- panderichthys
- Tiktaalik
- Acanthostega
- Ichthyostega
eusthenopteron
lobe finned fish, pelagic
panderichthys
-shallow water
- longer humerus, flattened skull
- can breath air
- still has many lepidotrichia
Tiktaalik
- weight bearing limb like fins that could take it onto land
- pectoral girdle independent of skull
- primitive lungs and gills, robust rib cage
Acanthostega
-more powerful pelvic limbs
- primary aquatic muscualr neck
- jaw modifications
Ichthyostega
- girdles stronger
- limbs
- digits
- ankle and wrist joints
- supportive ribs
stronger vertebrae - ear development
characteristics in shallow waters/wetlands/swamps/intertidal environments?
- flattened head
- air breathing
- loss of dorsal fins
- limbs
- internal nares
-lungs from swim bladder - vascularization and 2 circuit system
what happened before Romer’s gap
-pectorl and pelvic fins initial changes in bones of fins
- caudal fin tail
- gills-lived in water
what happened after Romer’s gap?
-lost tail fin
- no gills
- standard tetrapod limbs, feet and hands with 5 digits
- stood upright- no stomach or tail trails with footprints
