Marine Biology
Unit 1
CLASSIFICATION OF MARINE ORGANISMS
Worksheet
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While taxonomic classification is useful in grouping organisms on the basis of
phylogenetic similarities, it is not useful if we are concerned with how organisms are
related to their environment or how they interact with each other. Ecological (or
functional) classification schemes are useful for organizing information about plants and
animals in the context of how they live. Organisms that are functionally or ecologically
similar may be taxonomically very different and vice versa.
Organisms may inhabit the water column (referred to as pelagic organisms) or
may inhabit the bottom of the ocean (referred to as benthic organisms). Benthic fauna
may be further classified according to whether they are epifaunal (live on the surface of
the ocean bottom) or infaunal (burrow into the ocean bottom).
Many pelagic organisms, both plants and animals, have only very limited means
to control their location in the water column. These organisms depend upon the
currents to move them. They are called plankton. Autotrophs of this type are called
phytoplankton and heterotrophs are zooplankton. Pelagic organisms that can swim are
called nekton. Benthic organisms may be attached to the bottom (sessile) or may be
able to move about the bottom (motile). Some organisms normally live on the bottom
but have the ability to swim above the bottom. These are nektobenthic.
Several marine organisms are depicted in Figure 1. In Table 1, classify each of
these organisms according to its habitat, its motility, and write a few words explaining
why you assigned the classifications that you did.
Figure 1.
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Unit 1 – Marine Zonation and Biological Adaptations
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Marine Biology
Table 1.
Picture
No.
Habitat
Motility
Explanation
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Unit 1 – Marine Zonation and Biological Adaptations
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