Ocean Classification/ Living in a Fluid Environment

Question 1

Ocean regions by location:
Proximity to bottom
_____= open water
____= on the bottom (attached or not)

Answer 1

pelagic
benthic

Question 2

Ocean regions by location:
Proximity to shore
___= near to shore
___= out in open water

Answer 2

neritic

oceanic

Question 3

Ocean regions by location:
Light levels or depth
___= where light reaches
___= in the dark

*light reaches ~ ____m in open ocean

Answer 3

photic

aphotic

1000

Question 4

Ocean regions by location:
Bottom type= ____

Answer 4

substrate

Question 5

Regions of the ocean can be classified by physical parameters like ____, ____ and ___

Answer 5

temp
oxygen
light

Question 6

Regions of the ocean classified by temp:
List the 4 classifications

Answer 6

1. eurythermal: wide temp tolerances
2. stenothermal: narrow temp tolerances
3. homeotherm: regulates body temp (eg mammals)
4. poikilotherm: conforms to temp (fish/ marine intervebrates)

Question 7

many benthic animals like corals are _____, meaning they have a ___ temp tolerance

Answer 7

poikilotherms
narrow

Question 8

sea otters and most other mammals (and plankton) are ____, meaning they have a __ temp tolerance

Answer 8

homeotherms

wide

Question 9

How do oxygen levels vary with depth in the ocean?

Answer 9

• high O2 in surface because of mixing
• [low] in mesopelagic (~1000m)
• high O2 in deep ocean b/c oxygen is drawn down by decomp of dead phytoplankton and marine snow

Question 10

The pacific ocean has an oxygen minimum layer in the mesopelagic zone (~1000m). This is not so true in the atlantic ocean. Why?

Answer 10

Because in the Atlantic ocean, there aren’t as many areas of huge productivity, so no decomposition depleting the oxygen

Question 11

How far does light penetrate in coastal vs open waters?

Answer 11

coastal: light penetrates only 10s of meters

open ocean: light penetrates 100m or more

Question 12

___ light penetrates deepest into the water, and __ light penetrates the least distance

Answer 12

blue
red

Question 13

seawater is ___, so it resists change in shape

Answer 13

viscous

Question 14

how much viscosity affects an organism depends on its __ and how __ it moves

This is quantified by the ___ ____

Answer 14

size
how fast it moves

Reynolds Number (Re)

Question 15

Re=

Answer 15

Re=Vl
velocity x length(size)

so, velocity and size determine Re
*Re does not have units

Question 16

small and slow animals have a __ Re

large, fast animals have a ___ Re

Answer 16

low (eg less than 1)

high (eg 200 or 100000)

Question 17

viscosity leads to ____; particles entrained in flow move in these and do not ___

Answer 17

streamlines

cross

Question 18

Laminar flow vs Turbulent flow:

Answer 18

laminar flow= streamlines are all parallel & flow is very regular (slow)

turbulent flow= streamlines are irregular to chaotic

Question 19

T/F

type of flow (laminar/ turbulent) changes with speed, even with the same size organism

Answer 19

true

turbulent= higher Re, and Re depends on velocity and size

Question 20

laminar flow changes to turbulent flow when Re ____

Answer 20

increases

Question 21

• at high Re: ___ forces dominate, so flow is ____
• at low Re: ___ forces dominate, so flow is ___

Answer 21

inertial
turbulent

viscous
laminar (streamlined)

Question 22

Drag=

What’s a solution to drag for marine animals?

Answer 22

= a force exerted on an object by the liquid moving over it

solution: Dermal teeth (placoids): reduce the drag by making turbulence (breaking viscosity)

Question 23

Explain the no-slip condition (drag)

Answer 23

• flow over an object has a boundary layer
• at the surface of the object, flow experiences dray (fluid ‘glued’ to surface)
• water is essentially stuck at the surface= slows any animal down

Question 24

t/f
all dermal teeth/ scales are the same

Answer 24

false

varies between shark species (depends on how it swims)
also varies by body part on the same individual (diff scales on diff body parts)

Question 25

How have whales adapted to the viscosity of the fluid medium?

Answer 25

shed their skin to reduce drag!

• shed skin in warmer waters= reduces drag even with a high Re

Question 26

t/f
viscosity and drag are only harmful to animals

provide example

Answer 26

false
can be beneficial for finding prey/ avoiding predators

eg.
copepods ‘shape’ their fluid motion to advertise (to prey) or to conceal themselves from predators (control the speed around them)

Question 27

explain how copepods organize the fluid medium

Answer 27

1. as the copepod moves through water it creates a fluid disturbance
2. when it ‘hovers’ it creates a laminar feeding current using fine setae on the 2nd antennae
   - this disturbance appears as lines of = speed of fluid (isotachs)
3. the sensors on the antennae detect changes in speed of the isotachs in 3 directions

Question 28

t/f
copepods can detect water-borne signals of the isotachs in 2 dimensions

Answer 28

false
4 dimensions!
- x, y, z
and time

Question 29

viscosity varies with ___
- viscosity dominates at ___ ___
- inertia dominates at ___ ___

Answer 29

temperature

low temp

high temps

so: temperate waters more viscous, tropical waters less viscous

Question 30

What would be expected of an animal living in tropical waters (compared to temperate) if viscosity is considered?

Answer 30

animals living in tropical waters need structures to keep it more buoyant!
- b/c tropical (warm) waters less viscous, so needs structure to prevent sinking

Question 31

most tissues are ___ (more/less) dense than water
What are 3 adaptations to prevent sinking? (don’t want to waste energy staying afloat!)

Answer 31

more

1. shape: broad shape prevents sinking
2. projections: long spines prevent sinking
3. composition of tissues: less dense tissues to prevent sinking (eg oil droplets and gas chambers)

Question 32

How do siphonophores (hydrozoan cnidarians) stay afloat?

Answer 32

they have an oil droplet in their bell

it’s red (invisible in the ocean)

Question 33

The following all use a form of gas chamber to stay afloat. Explain the chambers of each
1. Portuguese man of war (Siphonophore)
2. Vellela vellela (chondrophora)
3. Janthina (gastropod mollusc)

Answer 33

1. gas filled bladder
2. has a sail, with little air chambers inside
3. secretes mucus, pushes air in, and hangs from the bubble

Question 34

How do jellyfish stay afloat?

Answer 34

they’re made of mesoglea: a jelly-like material made from hydrated collagen, which is neutrally buoyant due to density

Question 35

____ has adapted in marine animals to provide camouflage
- involves the whole organism
- has evolved many times
- they have ___ (not always eyes)
- the guts are ___ to camouflage what’s inside

Answer 35

transparency

photoreceptors

shiny

Question 36

sighting distance=

Answer 36

the maximum distance at which a prey animal is detected y an animal relying on visual cues

Question 37

How does transparency benefit the following:
1. prey
2. ambush predators
3. raptors

Answer 37

1. prey w short sighting distances aren’t seen by visually oriented predators
2. ambush predators with short sighting distance increase chances of entangling prey before being detected and avoided (eg jellyfish)
3. raptors can get within striking distance before being detected (except they have muscle, which is hard to make polarized)

Question 38

______ vision is an adaptation to see other transparent animals
- why does it work?

Answer 38

polarized

• light is polarized when it enters the water
• but birefringent tissues can be seen in polarized light

Question 39

how did we determine that squid hatchlings use polarized vision?

Answer 39

gave them regular food and food with sometime birefringent (something that refracts light like a muscle)

result: caught more food that was birefringent than the plain ones

Question 40

Some animals have adapted to see transparent animals by seeing __ light

Answer 40

UV
eg mantis shrimp and horseshoe crabs