3.1: Algae- The Evolutionary Link between Protists and the Plant Kingdom
Brown Algae
Red Algae
Green Algae
- are structurally diverse,
ranging from simple filaments
to large blade forms up to 100
m in length.
- are similar and more delicate
than brown algae. Many have
filamentous branches or are
multicellular.
- range from one-celled
organisms such as
Chamydomonas to
multicellular Ulva (sea lettuce).
- Large brown algae are called
sea weeds or kelp and are
found in marine ecosystems
along rocky shorelines.
- Some species can live at
depths of 175 m in the ocean.
Their red pigment
(phycoerythrin) allows them to
absorb the limited amount of
light that penetrates to those
depths for photosynthesis.
- Most green algae live in
water. Some species can live in
other environments, including
trunks of trees or on other
organism.
- Brown algae are anchored by
holdfasts. When the tide is in,
their broad, flattened blades
are buoyed by air vesicles
keeping them close to the
surface of the water and in the
sunlight.
- Like coral, coralline red algae
build up a layer of carbonate
around themselves forming
reefs.
- Green algae are believed to
be closely related to green
plants. Both groups (1) have a
cell wall that contains cellulose,
(2) possess chlorophylls a and b
, and (3) store food as starch.