Marine Ecology: The Deep Sea

The deep sea is the part of the marine environment that lies below the level of effective ______ ___________.

light penetration

Because of the lack of light penetration, what organisms cannot perform what?

phytoplankton cannot photosynthesize

How deep do the continental shelves go?

200m

0-200m in depth, this is the photic zone (lighted)

epipelagic

Which oceanic zone is also known as the photic zone?

epipelagic

200-1000m in depth, lower boundary in the tropics is the 10°celcius isotherm

mesopelagic

2000-4000m in depth, 10°-4°celcius (benthic zone is the bathyal zone)

bathypelagic

4000-6000m, overlying the plains of the major ocean basins (benthic zone is the abyssal zone)

abyssalpelagic

6000-10000m in depth, includes the open water of the deep oceanic trenches (benthic zone is the hadal zone)

hadalpelagic

0-200m

epipelagic

200-1000m

mesopelagic

2000-4000m

bathypelagic

4000-6000m

abyssalpelagic

6000-10000m

hadalpelagic

Light does not penetrate the deep ocean except in which zone?

upper mesopelagic zone

What is a lightless zone known as?

aphotic zone

What is relatively constant below the first hundred meters of the ocean?

salinity

In the ocean, pressure increases 1 atmosphere for each __m in depth

10

What is the approximate atm of the Mariana Trench?

1000atm

What are the four main adaptations of organisms that live under a lot of pressure?

no air-filled organs, low metabolic rates, homeoviscous adaptation, decreased-shell forming

What is the incorporation of more fluid lipids into cell membranes to help in membrane transport?

homeoviscous adaptation

Why do organisms in dealing with pressure reduce shell-forming?

calcium carbonate is more soluble under pressure

What is the place in the ocean where the greatest and most rapid changes in temperature occur?

thermocline

Why do thermoclines exist?

surface waters meeting deep waters, hydrothermal vents

Where are thermoclines the strongest?

tropics

Temperatures of the water emitted by hydrothermal vents can reach ___°celcius

400

Almost all of the water of the deep sea has its origin at the surface in what two seas?

Arctic, Antarctic

Oxygen-rich cold water sinks/floats and flows north/south.

sinks, north

Where is the oxygen minimum zone found?

500-1000m

What causes the oxygen minimum zone?

respiration of organisms coupled with the lack of interchange that occurs at the surface

The deep sea has no primary production except for:

chemosynthesis

Because food is scarce in the deep, most organisms get their food from:

marine snow

Mesopelagic fishes are normally colored:

silver

Mesopelagic fishes have few/many photophores

many

What are the light-producing organs found in fish?

photophores

Mesopelagic fishes have short/long jaws

short

Mesopelagic fishes have large/small eyes

large

Mesopelagic fishes have/do not have a swim bladder

have

Mesopelagic fishes have gills with many/few filaments

few

Bathypelagic fishes are normally colored:

red/black

Bathypelagic fishes have many/few photophores

few

Bathypelagic fishes have long/short jaws

long

Bathypelagic fishes have large/small eyes

small

Bathypelagic fishes have/do not have a swim bladder.

do not have

Bathypelagic fishes have a small/large heart

small

Bathypelagic fishes have gills with few/many filaments

few

Why is there a low mortality rate in the deep sea?

low predation pressure

T/F: the deep sea has a fast, indeterminate growth

false (slow indeterminate)

Deep sea ecosystems have low/high population densities.

low

Deep sea organisms have few/many eggs

few

Deep sea organisms have large/small eggs

large

Deep sea creatures have a slow/fast embryological development

slow

What does it mean to be semelparous?

Breed only once

T/F: Most deep sea creatures are semelparous

true

Deep sea creatures normally have a low/high metabolic rate

low

Deep sea creatures normally have a high/low water content

high

Deep sea creatures normally are smaller/larger in size

smaller

What is the oceans' (and earth's) largest ecosystem?

abyssal plain

Which two families dominate the abyssal plain?

echinoderms and arthopods

What do echinoderms and arthropods scour the ocean floor for?

detritus

What is the largest mountain chain on Earth?

Mid-Ocean Ridge

Mid-Ocean ridges occur at what type of plate boundaries?

divergent

All vent systems depend on the primary productivity of what kind of bacteria?

chemosynthetic (chemolithoauthotrophic)

Chemosynthetic organisms form organic compounds from what?

hydrogen sulfide

Organisms that live near hydrothermal vents usually have longer/shorter life spans.

shorter

What are the "cold water cousins" of hydrothermal vents?

methane seeps

What are bacteria feeding on in methane seeps instead of H2S?

CH4

Organisms live longer/shorter near methane seeps because of the colder water.

longer

What is an example of an animal that can live several hundred years near methane seeps?

polychaete worms

This fish has eyes that can look upwards as well as forwards. Their organs glow

due to the presence of symbiotic bioluminescent bacteria. To avoid detection, the fish uses counterillumination, which uses light to

break up the fishes' silhouettes so that when they are viewed from above, they blend in with the ambient light from the surface.

Pacific Barreleye Fish

exhibits characteristics of more ancient fish. No one has ever

seen this creature feeding, but it is known to be an ambush predator. It gets its name from its six pairs of collar-like gills with frilly

edges.

Frilled Shark

are named for their very large teeth compared

to body size (the fish only grows to about 6 inches long). The largest teeth actually fit into special sheaths on either side of its brain so

it can shut its mouth.

Fangtooth fish

is one of over 200 species of this kind of fish, all of which are known

for the bioluminescent lure that females have to attract prey. Males are much smaller and lack the lure. This fish is

covered in sensory filaments to detect motion around it.

Hairy Anglerfish

The scientific name of the vampire squid literally means "Vampire Squid of Hell",

though it is only six inches long and feeds primarily on floating detritus. The vampire squid does not have an ink sac, but can eject a

bioluminescent mucus when disturbed.

Vampire Squid

The species that gave rise to the mythological kraken, is said to grow to about 45 feet long.

It was only first filmed in its natural habitat in 2012, although that specimen was only 24 feet long

Giant Squid

1. Deep sea organisms have a number of unique biochemical adaptations because

a. low temperatures require different biochemistry

b. pressure affects protein function and membranes

c. many deep sea species are "living fossils"

d. the lack of light requires different pathways

b

2. Many species of deep sea crustaceans are predominantly red in color because

a. crustaceans are usually red

b. this makes them harder for predators to digest

c. the available nutrients only support the production of red pigments

d. the color actually makes them appear black in ambient light

d

3. In contrast to most deep sea communities, hydrothermal vent areas are biologically noteworthy because

a. many of the species are suspension feeders

b. bacteria are important

c. a number of vent species are large and form dense populations

d. many of the species are new to science

c

4. Which of the following are indications of the challenges faced by predatory fish in the deep sea?

a. disproportionately large mouths and teeth that curve backwards

b. many are bioluminescent

c. the show secondary adaptations for filter feeding

d. they have disproportionately large swim bladders

a