Marine Biology
November 2007
HABITAT DIFFERENCES
LAND VS. WATER
The ocean as a habitat is VERY different from land! Let’s explore some of these
differences.
LAND
1. large thermal oscillations common
2. niches are relatively easy to identify
WATER
the high specific heat of water ensures that
marine organisms are rarely exposed to large
changes in temperature. (Make sure to
review specific heat)
niches in the open ocean are a challenge to
identify.
on land.
3. Competitive exclusion principle applies on land in that a large population of one
species predominates. In the ocean the diversity of natural populations of
plankton seems to contradict the competitive exclusion principle in what is called
the “paradox of plankton”. That is tosay, that although most photosynthetic cells
in the sea compete for the same inorganic nutrients, often more than 30 species
coexist in small volumes of water.
4. LAND: terrestrial plants are immobile. OCEAN: most producers in the sea are in
constant three-dimensional motion. Give examples!
5. LAND:structural support required due to gravity. OCEAN: great deal of
buoyancy. DIFFERENT MASS/SIZE RATIOS AND SKELETONS.
6. Land: food web based on carbohydrates. OCEAN: food web based on protein.
7. Marine populations are characteristically different from those on land. OCEAN:
populations often characterized by rapid growth, larvae that suffer high mortality
dominate in ocean, populations are food limited (except during brief periods of
bloom). LAND: populations characterized by slow growth, dominated by adults
with low mortality, terresterial populations are limited by the availability of water.
8. LAND: a “patch” refers to the absence of species. OCEAN: a “patch” refers to the
presence of species.
SIMMILARITIES: Classification of marine environment is analogous to classification of
terresterial environments, in terms of relative productuvuty and energy flow.
EX/ open ocean = grasslands
Coastal areas = forests
Zones of upwelling and deep estuaries = rain forests and arear of intensive
agricultural activity.