Pelagic and benthic communities

Question 1

unity

Answer 1

All life forms are related, share the same underlying mechanisms for capturing and storing energy

Question 2

diversity

Answer 2

100 million species

Question 3

evolution

Answer 3

The maintenance of life under constantly changing conditions by continuous adaptation of
successive generations of a species to its environment

Question 4

natural selection

Answer 4

A mechanism of evolution that results in the continuation of only those forms of
life best adapted to survive and reproduce in their environment

main principles:
not all offspring survive
random variation
bearers of favorable traits are more likely to reproduce, so they are selected for
natural envr does the selection

Question 5

community

Answer 5

The populations of all species that occupy a particular habitat and interact within that habitat

Question 6

habitat

Answer 6

The place where an individual or population of a given species lives; its physical location

Question 7

niche

Answer 7

Description of an organism’s functional role in an habitat; its “job”
- The location and composition of a community depend on the physical and biological characteristics of
that living space
→ Physical factors: temperature, pressure, salinity, etc
→ Biological factors: crowding, predation, grazing, etc

Question 8

ocean zones

Answer 8

water and ocean bottom

pelagic zone - open water
pelagic zone consists of neritic zone (near shore, over cont shelf) and deep=water oceanic zone (beyond cont shelf)

ocean bottom (benthic zone) consists of littoral, sub-littoral, bathyl, abyssal, hadal zones

Question 9

pelagic community

Answer 9

live suspended in the water
subject to currents
little to no light below euphotic zone
little food
plankton (drift, weakly swim) and nekton (actively swim)

Question 10

benthic community

Answer 10

live on or in the ocean bottom

Question 11

phytoplankton

Answer 11

Plantlike, usually single-celled members
of the plankton community
produce approx. 50% of O2 in atm
part of food web
CO2 consumption and export of C to deep ocean

Question 12

cyanobacteria

Answer 12

0.2-2 micrometers
80% of all photo. activity in parts of ocean
grazed by micro-flagella and micro-ciliates

Question 13

diatoms

Answer 13

20-200 micrometers
over 5,600 species
most productive phytoplankton after cyanobacteria
can turn 55% of absorbed sunlight into carbs
glass house or silica frustule (siliceous external cell wall with two interlocking valves)
hole sin diatom allow passage of gases and nutrients but not bacteria and viruses

Question 14

coccolithophore

Answer 14

0.2-20 micrometers
covered in CaCo3 discs
make water appear chalky
ocean acidification dissolves shells

Question 15

dinoflagellates

Answer 15

single-celled, 2 flagella
1 propels and one rotates to receive best access to light
bioluminescent
form harmful algal blooms
may produce neurotoxins that harm filter feeders

Question 16

zooplankton

Answer 16

Heterotrophic plankton; the planktonic organisms that eat the primary producers

most numerous primary consumers of the ocean

graze on large cyanobacteria, diatoms, dinoflagellates, and other phytoplankton

mass of zooplankton is typically about 10% that of phytoplankton

70% are copepods
krill, “jellies” (jellyfish, salps, pteropods)
giant jellyfish are largest drifters

Question 17

vertebrates

Answer 17

fish are among most successful and abundant
gill and fins

some are ectothermic

Question 18

ectothermic

Answer 18

(cold-blooded)
breathe air with lungs, covered with scales and a relatively
impermeable skin

Question 19

endothermic

Answer 19

maintain a constant internal temperature that is generally
higher than their surroundings

all birds lay eggs, most live in S hem

Question 20

marine mammals

Answer 20

cetacea (dolphins, porpoises, whales)
carnivora (seals, sea lions)
sirenia (manatees and dugongs)
endothermic, breathe air, live young, hair

Question 21

benthic organisms

Answer 21

live on or in ocean bottom
clumped distribution
occurs when conditions for growth are optimal in small areas
rarely random dist

Question 22

rocky intertidal zone

Answer 22

The band between the highest high-tide and lowest low-tide marks on a rocky shore

Living in this zone is extremely difficult due to wave shock, rise and fall of tides, rapid
temperature change, predators from both ocean and land, annual movement of sediments, etc

The rise and fall of the tides lead to different time of exposure to sea and air

The shock of waves require different strategies by motile animals and sessile animals

but lots of food and niches

Question 23

deep seafloor communities

Answer 23

dark, hypersaline, cold, high pressure

orgs require little food, move slowly, live a long time