were defined by their mobility and heterotrophic nutrition strategy.
In this lab we will
continue to survey this diverse group of organisms and further examine distinctive
characteristics specific to plant-like protistans.
Plant like protists or algae (singular
several different autotrophic groups of usually
relatively simple living organisms that have the
ability to capture light energy through
photosynthesis, converting inorganic substances into
simple sugars. Many taxonomists have traditionally
regarded green photosynthetic protistans as simple
plants (Viridiplantae), and indeed some chlorophytes
are closely related to the higher plants. Others
appear to represent different protist groups,
alongside other organisms that are traditionally
considered more animal-like (that is, protozoans).
Thus algae do not represent a single evolutionary
direction or line, but a level of organization that may
have developed several times in the early history of
life on earth (polyphyla).
Algae range from single-celled, colonial to multi-
cellular organisms, some with fairly complex forms.
While many green algaes share many characteristics
with plants, they all lack plant organs: leaves, roots,
flowers, and other organ structures that
characteristic of higher plants. Algaes are usually
found in damp places or bodies of water and thus are
common in terrestrial as well as aquatic
environments. However, terrestrial algae are usually
rather inconspicuous and far more common in moist,
tropical regions than dry ones, because algae lack
vascular tissues and other adaptations to live on
land. Some algaes can live in non-moist
environments by developing symbiotic relationships
with fungi (lichens).
The algae are the dominating primary producers in
aquatic ecosystems, on unstable substrates (muds
and sands) and in intertidal marine habitats. Algae
are commonly exploited as foodstuffs, food additives,
The body portion of an algae is called a thallus. The thallus of an algae is usually haploid and
the variety may define specific groups. There are four types of thalli, based on the following
- A Structure that consists of a single cell, most are aquatic
organisms, and form the phytoplankton, a population of photosynthetic organisms the forms
the foundation of the food
chain. They produce half of the worlds carbohydrates
and are among the major producers of oxygen in the atmosphere.
- Have a structure that consists of groups of cells acting in a
coordinated manner. Some of
these cells become specialized. This division of labor
allows colonial algae to move, feed, and