deep sea

Question 1

what’s bathymetry and how can it be done

Answer 1

Measurement of the depths of water

Using a weighted line

SONAR / echosounder – single beam & multibeam

Satellite altimetry – subtle variations in sea level

Question 2

explain the mechanism of seafloor

Answer 2

Continental shelf

Continental slope

Fracture zone

Seamounts (& sea knolls)

Trenches

Abyssal plain

Canyon

Basin

Question 3

what is a histogram?

Answer 3

distribution of elevations of earth’s surface

Question 4

hypsographic curve

Answer 4

cumulative elevations of earth’s surface

Question 5

explain the ocean zonation

Answer 5

Neritic zone – shallow subtidal (0 to ~200 m)

Oceanic zone – deep subtidal (>200 m)

Euphotic (photic) zone – area of the ocean where there is
enough light for photosynthesis to occur

Disphotic zone – dimly lit zone (not enough light for
photosynthesis)

Aphotic zone – no light

Question 6

epipelagic

Answer 6

<200 m

Question 7

mesopelagic

Answer 7

200-1000 m

Question 8

bathypelagic

Answer 8

1000-4000 m

Question 9

abyssopelagic

Answer 9

4000-6000

Question 10

hadopelagic

Answer 10

> 6000

Question 11

define benthic with an example

Answer 11

organisms that live in or on the bottom sediments of rivers, streams, and lakes (clams, crabs)

Question 12

define pelagic with an example

Answer 12

Pelagic – living in the open sea or water column

Planktonic - drifting

Nektonic - swimming

Question 13

vampire squid adaptations (inv)

Answer 13

jet propulsion for escaping the predators

slow metabolism to survive OML

Question 14

anglerfish adaptations

Answer 14

gray or dark brown color that allows them to blend in with the depths of the ocean and hide in dark places along the ocean floor.

flashing bulb that hangs from the top of its head

Question 15

what are the challenges to life in the deep sea?

Answer 15

Cold water (2-3oC)

High pressure (up to 1100 atm)

No light or very little light

Limited amount of food

(nutrients moderate but useless)

Moderate amount of oxygen below oxygen
minimum layer (500 – 1000 m)

Difficulty in finding mates

Constant conditions (salinity, temperature,
oxygen, darkness)

Question 16

amount of oxygen

Answer 16

Deep ocean has reasonable amount of oxygen because rate
of O2 consumption is minimal, high O2 solubility and
thermohaline circulation

Question 17

biological adaptation to oxygen

Answer 17

Low metabolic rates (rate of oxygen consumption)

Infrequent & slow movement e.g. plankton, idiot fish
(overfished!)

Haemoglobin with high oxygen affinity – very efficient
at extracting what little oxygen is present

Question 18

adaptations to temperature

Answer 18

Low metabolic rates

Low activity levels

Question 19

adaptations to pressure

Answer 19

No air spaces / no swim bladders in deep sea fishes

Flabby / gelatinous bodies e.g. jellies, ctenophores,
siphonophores, many fishes

Minimal calcification of bones so that they are soft and
flexible

Question 20

adaptations to light

Answer 20

Large eyes to capture limited light e.g. squid

Tubular eyes e.g. barreleye fish

Yellow lenses to detect photophore light (Blue Planet fish)

Excellent sense of smell

Pigmentation: camouflage with colour (black, red,
silver) or lack of pigment (transparent)

Some species have an orange- or red-coloured gut so
that they can eat bioluminescent prey and not be
detected themselves e.g. jellies, shrimps

Countershading

Bioluminescence

Question 21

proposed applications of engineered bioluminescence

Answer 21

Glowing trees to line highways to save government
electricity bills

Christmas trees that do not need lights, reducing danger
from electrical fires

Agricultural crops and domestic plants that luminesce
when they need watering

New methods for detecting bacterial contamination of
meats and other foods

Bio-identifiers for escaped convicts and mental patients

Detecting bacterial species in suspicious corpses

Novelty pets that bioluminesce (rabbits, mice, fish)

Question 22

adaptations to food

Answer 22

Some food drifts down from upper layers of ocean e.g.
whale carcasses, marine snow, dead plankton, detritus
(vampire squid)
Vertical migration (find food in shallows)

Large mouths e.g. gulper eel

Hinged jaws e.g. stoplight loosejaw fish

Long teeth that point inward e.g. viper fish

Large expandable stomachs e.g. black swallower

Ambush predators rather than expending a lot of energy
searching for food

Bioluminescent lure to attract prey e.g. anglerfish

Male anglerfish is permanently attached to and receives
nutrition from female

Question 23

adaptations to reproduction

Answer 23

Bioluminescence to help find mates

Excellent sense of smell

Male anglerfish has a special organ to locate female
anglerfish - he provides sperm to the female to which he
is permanently attached (and she provides nutrients to
him)

Question 24

gigantism

Answer 24

Lack of substrate for pelagic species means that
they can be very large e.g. the siphonophore Praya
can be up to 40 m long

Question 25

human impacts

Answer 25

minimal
Both on deep sea ecosystems and (especially) on
hydrothermal vent ecosystems due to their inaccessibility

But over time marine litter & chemical pollutants can make
their way to the deep sea and wastes (including nuclear waste)
have been stored in the deep sea

Overfishing e.g. idiot fish

Bottom trawling is damaging to seamount ecosystems

Climate change and ocean acidification

Ocean acidification decreasing marine snow sinking rates

Scientists exploring the deep sea

Deep sea mining is an impending issue