Nekton - Vertebrates Flashcards
what’s an example of Agnatha?
hagfish
lampreys
what’s an example of Chondrichthyes?
sharks
what’s an example of Osteichthyes?
teleosts
what is agnatha?
jawless fishes
what are chondrichthyes?
cartilaginous fishes
- sharks
- skates
- rays
- chimeras
describe Chondrichthyes
- cartilaginous skeleton
- replaceable tooth rows
- dermal skeleton
describe osteichthyes
- bony fishes
- true bony skeleton
- more diverse than Chondrichthyes
- teeth fixed in jaws
describe lampreys
freshwater
eel-like
parasites
describe hagfish
- marine
- eel-like
- scavengers
- eat dead animals and worms and snails
- tie self into a knot and move forwards
- rough skin - absorb nutrients through skin
- secrete immense amount of slime for defense = slime eels
why do hagfish have rough skin?
allows for extra nutrients to get absorbed because scavenging can only provide so much nutrients
what are the kinds of fishes?
- rover
- surface oriented
- bottom fish
- deep bodied
- eel like
whats an example of surface oriented fish?
flying fish
whats an example of a bottom fish?
small fish, snails and crabs
-> dorsoventrally flattened
whats an example of a deep bodied fish?
herbivores or coral specialists
-> specialized bottom feeders
what is form a combination of?
- acceleration -> maximized by repulsion
- cruising -> continued undulation -> stiff bodies
- maneuvering -> deep bodied fish. sudden changes in movement
poikilotherms
- most fish are cold blooded but some are endothermic to allow for hunting in cold waters
-> tuna and swordfishes
what is an example of a cruising specialist?
tuna - predator
what is an example of maneuvering specialist?
butterfly fish - coral and herbivore
what is an example of an acceleration specialist?
barracuda - predator
what does swimming involve?
undulation of entire body
how does a shark move?
thrusts depending on the shape of the tail
what are the components of force during swimming?
propulsive element
side force
thrust
normal force
mola mola
- three species
- pufferfish
- slow moving
- deep diving
- feed on jellyfish
compare sharks and bony fish
sharks have cartilage making them light
bony fish have mineral skeletons making them heavier
how do sharks control buoyancy?
fat storage in liver
how do bony fish stay neutrally buoyant?
regulate bulk chemistry
are bones and tissues denser than water?
yes
what is the purpose of swim bladder?
in bony fishes so gas is exchanged by a network of capillaries called the rete mirabile
rete mirabile
exchange of gas in from blood into swim bladder
- oxygen is exchanged into swim bladder and O2 leaves and goes into bladder
oxygen use in fish
oxygen exchange
- water flows over gill lamellae and oxygen diffuses into gills
what is countercurrent exchange?
blood flow is in opposite direction of water flow
- blood flow picks O2 which is opposite to water
solute exchange in sharks
isotonic
- blood osmolarity almost the same as seawater
- sharks do not need to drink water
- solute excretion via rectal gland
-> same solute concentration as water
solute exchange in bony fish
hypotonic
- blood has fewer solutes than sw
- drink a lot of water and excrete solutes
- solute excretion over gills (via chloride cells)
can sharks live in freshwater?
yes for extended periods as they retain the salt from the ocean and recycle it in the body
bull sharks
- conserve urea
- absorb salts
- juveniles found high in estuaries -> maintain internal salinity and can be found very high up in fresher water
dogfish
- unable to survive long-term fresher than 50/50
- known to enter estuaries
- cannot live higher up in estuaries
how do predatory sharks feed?
teeth produced by tooth bed but temporary
- dentine but no root
- drop one a week minimum
- teeth in skin -> placoids, provide protection but light weight
basking sharks
- larger filter
- gill rakers -> bars on gills with filaments that collect tiny particles
- temperate water distribution
- feed on copepods, shrimp and fish eggs
- passively consume water and captures the floaty bits
whale sharks
- filter plankton using gill rakers
- long life span
- ovoviviparous -> birth to live young hatched from eggs inside female
- largest known extant fish
- exchanged
- huge migratory areas
- overlap with tuna
- hunted for fins illegally
oviparous
lay egg cases
- sharks and rays
viviparous
placental
- birth to live young
- bull shark
ovviparous
produce eggs which hatch inside female
- birth to live young
- dogfish
- whale shark
sensory systems
- hearing
- lateral line systems
- ampullae of Lorenzini
- smell
- eyesight
describe the hearing system
ears behind eyes
- hair cells very sensitive to low frequency sounds and have good directional hearing
describe lateral line system
hair cells in fluid-filled canals down head and trunk - detect water vibrations
- separate nerve endings
ampullae of lorenzini
small pores filled with glycoproteins detect electrical fields
smell
excellent smell through nares
eyesight
color vision and see well in low intensity with two specialized features
what is used for low light in eyesight?
tapetum lucidum
what is tapetum lucidum?
reflective surface behind the retina boosts the visual signal in low light levels
what is nictating membrane?
cover over the eye to protect it from damage when feeding
what are the 7 species of sea turtles?
- loggerhead (most common)
- green (two subspecies possible)
- hawksbill
- kemp ridleys and olive ridleys
- flatback
- leatherback
describe leatherback turtles
- adaptions for anaerobic respiration during long dives
- small lung
- sphincter that shuts lungs off
- leatherback has compressible shell
- increased blood vol and increased concentration of myoglobin
- largest
- fastest -> high Re
- longest migrations
- single member of group with bony skin
- feed mainly on jellyfish
-»»> critically endangered
ridleys’ turtle
mass egg laying events “arribadas”
- only sea turtle that does synchronous egg laying
loggerhead
- massive head
- strong jaw for eating molluscs
- keystone species for role in moving nutrients on reef
- large number of eggs per nest
- eats shells and leaves calcium out for the ocean floor
describe the life history of turtles
- maturity is 11-40 years
- females return to land to lay eggs
- lay up to 100+ eggs/nest
- incubation time is approx 2 months
- young turtles fed upon by birds and fish
- eggs dug up for food by people
- temp dependent sex determination
how does temp affect sex determination?
climate change means the globe is warming up meaning that there are more F than M
- females incubate above 31C
- males incubate below 27C
