Lesson 7 Flashcards
locomotion
- ## thrust can be broken down into the forward thrust and lateral thrust which add to the reaction of water
lateral thrust
has to be offset by the dorsal fin to make sure the fish doesn’t go in circles
– eels can bend in ore than half of a sine wave
trout
- carangiform
- undulations are limited
- bends into half the sine wave length
boxfish
ostraciiform
—- even less of a sine wave
—- restricted by the caudal din
shapes of fishes
- cross section to length ration is very close to 0.25 –>AKA sweet spot forhydrodynamics
–> drag is reduced to its minimum
–> SHAPE again and again
shape of fishes (why does breadth and length matter)
- a wider fish pushes away a lot of water – cross sectional area
- have to be longer to be narrower
-but length also has some drag to it
viscous frictional drag
- resistance of water following across the surface area of the fish
- super long and narrow fish (greatly increased friction drag, but greatly decreased pressure drag)
reproduction
lof of variation between freshwater and marine telosts
freshwater reproducition
small numbers of large eggs (maximize quality over quantity)
- eggs attach to a surface like rock
- look like mini adults
marine reproduction
tend to lay large number of very small bouyant eggs
- will float
- look like true larvae
teleosts have many interesting sex changing behaviors
most are ghonochronystic –> sex does not chage
BUT … are a number of exceptions
Clown fish – immature –> male –> female
- female needs to grow and have enough energy to make the strong and robust eggs
protogynous hermaphroditism
born female, them eventually become male
pelagic fishes
- open ocean
- away from shore
benthic
- along the bottom
- bottom of the open ocean
where is most of the biomass
- along the top of the ocean
– meaning you have usually go to the surface if you wanna eat
mesopelagic migration
- fishes that migrate from the deep ocean to the top
- undergo daily movements
surface irradance
measure of light on the surface of water throughout the course of the day
isolume
the depth that maintants that amount of bright light changes throughout the day
ex: to still have 1 lumen of light during sunset, you have to be higher up in the water column
scattering lines
proportional to the time of a sound wave emitted from the surface of the water (from a speaker_ returning to the durface
– why does the time get shorter and shorter?
– has to do with what its bouncing off of (FISH)
– as the sun is setting – the time for the sound wave to come back got shorter and shorter MEANING that almost all the mesopelagic fish are going from the deep to the surface everynight to feed
– can’t go during the day becuase their primary predators can only really see in the day
benthipelagic
- deep deep dwelling fishes
- have reduction in bone
- some have really enlarged stomachs
WHY - when you live in the sea, you don’t come across food that often
- if you come across food, even bud food – engulf it while you can
- most go their whole life without reproducing
- lot of them have these light emitting bacteria to find eachother, or even to use to lure prey in
coral reef fish
- many have this incredible mouth protruding ability
- vast majority are acanthopterygian fish
- different modes of feeding
- coral reef itself gives them places to hide like nowhere else
— great place to escape predation
—maybe why they’re so brightly colored
— bright colors are great for attracting a mate – but also for predators
