Lesson 6 Flashcards
internal fertilization
you don’t give live birth if you don’t have internal fertilization, but you can have internal fertilization and not have a live birth
placoderms
- covered in this thick boney shield
- ancestral of these were primarily marine, but some were form a freshwater environment
- pelvic fins
—distinct in modern condrichthiean
—males have clapers to internally fertilitze
——- internal fertilization suggests complex mating
extant clades of neoselachii *sharks and rays)
- sharks
- skates
- rays
- rabbit fishes
- ^^^^ living descendants of the entire radtiation of gnathostomes
^^^^ cartilaginous fishes
chondrichthyes
- cartilagineous fishes
- primary a freshwater group a longggggg time ago
- now –> mainly marine
- scales are possible remenant of dermal bone
- kind of like teeth – dentine
- constant string of replacement teeth when a tooth falls out
cladoselache
- mouth opening is terminal
- extinct chondrithye fish
- jaw support is not hyostylic – its anphostilic
- upper jaw is firmly attached to the chondochrnium
- body is only supported by a notochord
- basal elements anchor fin into place – not the mobility of a fin
- proabably pelagic predators (open ocean)
- lacked body scales and calcification to possibly increase bouyancy
damocles
- shark head with a clasper
- nuchal spine (only in males_ –> might be a sexually selective trait, we don’t know
helicoprion
no one knows how to arrange this fossil
– has a tooth whorl – teeth wrap into spiral
xenacanthus
- calcified cartilaginous skeleton
- bone vs. cartilage
- bone is vasularized – can remodel itself
– cartilage is not really healable
hybodus
- terminal mouth
- amphystylic jaw suspension
- heterodonts
- 3 basal cartilages supporting each fin
- triblastic fin attachment –> probably makes it more moveable
- claspers for courtship
heterodonts
different forms of teeth that serve different purposes
hybodus (heterocercal tail)
- caudal fin with 2 asymmetrical lobes
lobe on tail influenes swimming pattern – how it propels and generates lift - pterolepis had a hypochrodal tail
leading edge tail on tip
lift is upward right at the tail
leading edge of tail on bottom
- vertical component is downard
- lift is downward
evolution and radiation of extant sharks
- overhanging ventral position of mouth
- solid calcified vertebra
- sensory systems
sensory system of extant sharks
- neural masts of lateral line system
- ampulaie of lorrenzii (use electric fields to sense prey)
think about how you hear and can find out where things are – how do you know the direction of sound
– for sound that comes from the right, it takes longer for sound to reach the left ear
— interaural time difference
what allows you to identify location (sound detection –> similar mechanism in other vertebrates
if sharks are following an odor plume of a bleeding surfer, how do they know which direction the smell is coming from
there could be a time idfference between the odor hitting each nostril which could be used to identify direcion
^^^Hypothesis for what gives rise to the wide heads in hammer head sharks
disconnected skull bone movement: cranial kinesis
why it appears that sharks can kind of shoot their jaws out
true/fasle: internal fetilization is universal for sharks
true – they can lay eggs or have live birth
what kind of species is the shark
- K species
- only so much energy to go around
- no evidence of parental care in sharks
evidence of a social network in the tiger shark
- 2 individual sharks had acoustic receivers on them –> when they got close enough they sent a signal and were able to find out that some sharks have “friends” “bestfriends” and “mutual firends_
– fission and fusion behavior - social groups would undergo fission and fusion (thought to only occur in mammals)
fission and fusion behavior
describes the movement of social groups
life history traits
- life span
- annual mortality rates
- fecundity
- size at maturity
sharks life history
- sharks have a life history that does not allow for rapid population recovery
- huge fecundity difference
- many in danger - tend to cross international boundaries and it’s hard to regulate in more than one country
why has the loss of sharks in the waters off the coast of north carolina resulted in a decline of things like clams, scallops, and muscles
rise of intermediate species that feed on shellfish
- sharks are a keystone predator
batomorphi (rays)
- have about 700 extant species
- characterized by having these specialized teeth
- protrozable mouth to suck up food
- unusual body shape
- flattened pectoral fins
distinguish skates vs rays
- skates have this elongated, thick stocked tail with 2 dorsal fins
- skates are obipherous - lay eggs
- rays give live birth
chimaeriformes
- usually found in deep water
- unknown purpose extension
chondrithyes
cartilagenous fishes
–osteichthyes (bony fishes)
—–ray finned fishes
—–lobe finned fishes
————-tetrapods and all of us
devonian
age of all fishes
- all the older major lineages of fishes were present during that time
osteichthyes
ray finned and lobe finned fishes that have more than 30,000 extant species
osteichthyes characteristics
- distinguished by the presence of enochondral internal bone
- has dermal and parachondral
- presence of gas containing lung that us used for breathing
— ventral to the gut
dermal bone
forms in our dermal region as the components of it precipitate right there without any sort of structural skeletal component preceeding it
endochondral bone
- cartilage that turns into bone
- found in our humerus and femur
lepidotrichia segments
- finned rays have this
- dermal bones that are modified from scales
lobe fin fish
sarcopterygian
- extension branches out like a feather
ray finned fishes
actinopterygian
- rays extend from bone from kind of like a fan
cerebral hemisphere of the vertebrate brain
- vast majority of the forebrain forms an invagination and the 2 hemispheres form by rolling into that area
how to actipterygian’s hemispheres form
develop by rolling out latterally
—- evaginates
evaginated forebrain
- how it develops affects most of all the wiring in the brain
- the extending of axons hae to dins the right conection place during development
- when your brain evaginates, the axons make connections with completely different parts of the brain compared to when the brain invaginates to develop
evolution of circulatory system
originally
– no true division
— oxygenated blood doesn’t really keep separated form the deoxygenated blood
BUT
– emergence of atrial septum (sarcopterygian)
do teleosts have a lung
no
- they have an air bladder – not used for ventilation
– used to aid in bouyancy
teleosts
- appeared in the mid triastic
- radiated rapidly into many many species
heterocercal tail
bony shaft goes up and there is an asymmetry between the dorsal and ventral lobes
homocercal
almost the same length of dorsal and ventral lobes
bichir
- ray finned fishes
- predatory
sturgeon and paddle fishes
benthic fishes
- dwelling of the bottom of the water column
- lack endochondral bone
- barely any skeleton
- presence of large armour like scales
- only found in the northern hemisphere
why are sturgeons at risk of extinction
caviar
holesit (gnars and bowfins)
needlelike teeth for prey capture
teleosts
- about 470 families evolved by the beginning
- fairly recent group compared to the others
- found in all nieches across the earth
- characterized y movable premaxilla and maxilla
what are teleosts characterized by
- recudtion in heavy armour
- evolution of a new jaw mechanism
- posterior end of maxilla is free from other bones od the cheek
- hypermendibular can swing out – increase the volume of the oral branchial cavity
benefits of the hypermendibular being able to swing out
- increae in hydrodynamic efficiency
- how little drag they canhave cutting through the water
- enhances the gripping of prey and increases the predator approach velocity
common american eel
- takes about 25 years for a female to reach maturity (do so in fresh water and breed in salt water)
- catadromous – maturation in freshwater then migrate to deep ocean
- larvae will drift then swim to freshwater
otophysi
have webarrian apparatus
weberian apparatus
set of bones that hook up their gas bladder to their semicircular canals of the auditory system
- purpose: aids in hearing
- sound pressure (how loud it is) needed to elicity a behavioral response
— it takes far less loud sound for a goldfish to hear it compared to a tuna
— more sensitive to sound
what about the weberian apparatus allows for the increase in sound sensitivity
in order to hear the sounds - need to resonate
- sound waves resonate when they pass through mediums
- water is usually main medium
- no substantial difference in density for the outside and what the sound is carrying through in th efish
- swim bladder – air filled chamber – difference in density allows for sound to vibrate
—- the bone picks up the sound and it vibrates along to the hearing apparatus
euteleostei
- endotherms (production of heat)
- the temperature of the pectoral fin stay at around the same temperature –> somehow the fish is regulating its body heat – doesn’t follow the temperature change as the sun sets
- have countercurrent heat exchanger in the gills
—– alternating deoxygenated and oxygenated flowing in opposite directions making a countercurrent heat exchange
—– helping to maintain heat
—– Opah vs. Tuna
——— opah is able to stay at a deeper depth (bc of temp) and explore more habitats
acanthopterygii
- stiff bony fin spines in the dorsal, anal, and pelic fin
- pectoral fin has evolved to move up on the side of the body –
- has lost the duct from the gut to the gas bladder
midshipman telosts
reside in the intertital rocky shores
- the male (big) find a little opening/crevice in these rocks and fight off other males – they humm for a long time and it’s sexualy attractive to females
—- she swims over and they spawn
2 kinds of male midshipman teleosts
- listens to territorial mans’ hum
—- sneaks into the crevice and spawns
SNEAKY
cicloforms
African ciclid
- have these dominance hierarchies
- single dominant male, bunch of femals, then subordinate males
- males flash these eyebars
- dominant may die: one of those will rapidly ascent to a dominant male
- underlying neural mechanism
experiment with African ciclid
- secretly dipped in and scooped out the dominant male
- within minutes of the lights turning on – they start making all these terrirotrial and sexual behviors
—- discovered that in the ascending males – there was a rapid expression of a gene (great increase in gene expression when ascending)
seahorses
- males get pregmant
- certainty of paternity
- females lay their eggs and he captures them in his pouch and fertilizes them
