Activity: Pelagic Zones - Where To Live in the Ocean
The marine ecosystem is the largest aquatic system of the planet.
Its size and complexity make it difficult to
deal with as a whole.
As a result, oceanographers divide the ocean into zones according to physical
characteristics, just as the land environment that we live in is divided into zones (tundras, forests, grasslands,
The two major zones of the ocean are the sea floor, or bottom region, called the
and the watery region above the sea floor called the
Each of these is further divided into
correspondent zones according to their living conditions (depth, temperature, and sunlight penetration).
In this activity, the students will demonstrate understanding of the concept of zonation in the ocean
explaining why oceanographers divide the ocean environment into zones,
discussing the causes of pelagic zonation,
identifying the different pelagic zones in which the marine organisms can live, and
describing the physical characteristics of each pelagic zone.
Ocean Zones: Where To Live in the Ocean
Introduce the subject of zonation by emphasizing that the marine ecosystem is the largest and most
variable aquatic system on the planet.
Establish the convenience of dividing it into zones, each of which
can then be studied and discussed in terms of the ecological principles that govern life in them.
Have the students discuss how conditions like light penetration, availability of food, and water temperature
change with increasing depth across the pelagic region.
Ask the students about examples of pelagic organisms and the types of adaptations that
they may have to survive in the zones where they live.
In general, in the epipelagic zone, there is light, warmer waters, and nutrients.
Since plankton need light, they
will have adaptations to reduce their sinking rates.
Nektonic organisms will exhibit coloration, body shape, and
special body features that increase their chances for survival.
Silvery, countershading, or warning colorations
accompanied by fusiform, rod, depressed or laterally compressed bodies, and the presence of spines are among
the adaptations to survive in the epipelagic or photic zone.
In deeper waters, there is no light and not much
Nektonic organisms in these regions will tend to be smaller and darker, with big mouths and long, sharp
They will have bigger eyes, and others will lack eyes or be bioluminescent to attract prey.