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Comparative studies of natural groups of organisms

Phylum Euglenophyta Distinctive features of phylum
This phylum comprises of unicellular Euglenophyta
aquatic algae, most of which live in Members of the phylum Euglenophyta
freshwater rich in organic content; many are distinguished from other phyla by the
possess flagella and are motile. The outer following features:
part of the cell consists of firm but flexible (a) They have pyrenoids for storage of
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layer called a pellicle or periplast, which starch.
cannot properly be considered a cell wall. (b) They have eye spot (photoreceptor)
Some euglenoids contain chloroplasts for detection of light intensity.
that contain chlorophyll a and b; the
photosynthetic pigments, as in the phylum (c) They possess both plant and animal
chlorophyta. Others are heterotrophic and characteristics (Figure 3.16). Plant
can ingest or absorb their food. Food is characteristics include; presence of
stored as paramylon. Reproduction takes chloroplasts containing chlorophyll,
place by longitudinal cell division. The pyrenoids, and utilisation of nitrites
most common organism in this phylum is or ammonia as sources of nitrogen.
photosynthetic protozoan called Euglena, Animal characteristics include;
usually found in water bodies, such as possession of myonemes (muscle-like
ponds. strands), and flagella for locomotion
(euglenoid movement), utilisation of
General characteristics of phylum amino acids, peptones or polypeptide
Euglenophyta as a source of nitrogen, presence of
(a) They have chloroplasts that contain gullet with sphincter and reservoir for
chlorophyll for photosynthesis. ingestion of food.
(b) Most of them are found in freshwater;
only a few are marine dwellers. Flagellum
(c) They are protected by pellicle which Eye spot
Reservoir
surrounds the cytoplasm, as they Contractile
lack cell wall. This enables the cells vacuole
to change shape because they move
around by euglenoid movement by the Chloroplast
aid of myonemes. Nucleus
(d) They have two flagella. One of them
is short, while the other is long; these
arise from the bottom of a reservoir. Pellicle
(e) They have eye spot (photoreceptor)
for detection of light intensity. Figure 3.16: Structure of the Euglena
(f) They have pyrenoids for storage of Adaptations of Euglena
starch.
(g) They sometimes feed heterotrophically Euglena is able to survive freely in its
by using the gullet. environment due to presence of the
following adaptive features:

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