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| Flagellar
beat pattern of volvocine green algae, such as Chlamydomonas;
the flagella are similar in length and beat with a breast-stroke pattern,
pushing against the water and driving the cell forwards. The flagella may
also adhere to surfaces to keep the cell in one place, and with a different
beat pattern the cells can be driven backwards. Animation
by Rosemarie Arbur. |
Flagellar
beat pattern of gliding euglenids, such as Peranema. Some euglenids
swim, and some euglenids glide. Those which glide may have one or two emerging
flagella, and one or both is usuually pressed against the substrate. In
some, such as this, the activity of the flagellum is retsricted to beating
an the anterior end. Other species have a sweeping motion. It is probable
that the beating is not the cause for motion. Euglenid flagella are generally
much thicker than the flagella of most other organisms. Animation
by Rosemarie Arbur. |
Flagellar
beat pattern of swimming euglenids, such as Euglena. Some euglenids
swim, and some euglenids glide. Those which swim form loops in the flagella,
and these pass from base to tip. the flagella tend to be directed towards
the rear, and this creates the thrust which moves the cell forwards. Euglenid
flagella are generally much thicker than the flagella of most other organisms.
Animation by Rosemarie
Arbur. |
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Flagellar
beat pattern of heterokont (stramenopile) flagellates, such as Cafeteria.
The heterokont and related flagellates have stiiff hairs attached to one
of the flagella. these are too delicate to be seen by light microscopy.
These are a wonderful invention. The flagellum beats with a sine wave
which passes from base to tip, but the hairs move in a way which draws
water towards the cell. this brings food to those which are heterotrophs.
Detached cells swim with the flagellum in front of the cell. Animation
by Rosemarie Arbur.
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Flagellar
(ciliary) beating of an opaline, such as Opalina. The opalines
are a very unusual form of stramenopile, and most live in the posterior
part of the intestines of amphibia. They absorb dissolved food through
the cell surface. The body is covered with large numbers of flagella,
and these beat in a way which creates forces across the surface of the
cell, allowing the cell to glide forweard through the fluid. Flagella
located in packs and beating so that the thrust moves across the surface
of the cell rather than perpendicular to it, are referred to as cilia.
Animation by Rosemarie
Arbur.
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Flagellar
beat pattern of collar flagellates (choanoflagellates), such as Monosiga;
there is a single flagellum which beats with a sine wave that progresses
from the base to the tip. Fluid is drawn through the collar of fine pseudopodia
which encircles the base of the flagellum and small particles of food, such
as bacteria, are trapped against the collar. Detached cells swim with the
body in front and the flagellum beating behind. flagella are similar in
length and beat with a breast-stroke pattern, pushing against the water
and driving the cell forwards. The flagella may also adhere to surfaces
to keep the cell in one place, and with a different beat pattern the cells
can be driven backwards.Animation by Rosemarie
Arbur. |
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Flagellar
(ciliary) beating of an ciliate, such as Paramecium. Ciliates
have large numbers of cilia arranged in rows (kineties) over the cell
surface. Cilia are just short flagella which beat stiffly, the power stroke
pushing across the cell surface. Usually, the cilia will beat slightly
out of phase with their neighbours. This is referred to as metachronal
beating. In active cells, this appears like a wave passing across the
body of the cell, with the crest of the wave being where the cilia are
ready to begin their active beat.Animation by Rosemarie
Arbur.
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Flagellar
(ciliary) beating of an ciliate, such as Paramecium. Ciliates
have large numbers of cilia arranged in rows (kineties) over the cell
surface. Cilia are just short flagella which beat stiffly, the power stroke
pushing across the cell surface. Usually, the cilia will beat slightly
out of phase with their neighbours. This is referred to as metachronal
beating. In active cells, this appears like a wave passing across the
body of the cell, with the crest of the wave being where the cilia are
ready to begin their active beat. A pattern of co-ordination in which
the crest of the wave moves in the same direction as the power stroke
of the individual cilia is referred to as symplectic beating.Animation
by Rosemarie Arbur.
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Contractile
vacuole of peniculine ciliates (such as Paramecium) fluid is
collected in the spongiome, and delivered to the vacuole, which contracts,
pushing a little fluid back into the ampullae, before the pore breaks and
the fluid is released.Animation by Rosemarie
Arbur. |
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| The
reversal behaviour. Protists, like other organisms, react to their world
in different ways. In this case, the ciliate reacts to edges by 'reversing'
its direction of swimming, tumbling, and then moving in a new direction.
Repeated, this behaviour will alow the ciliate to navigate around an obstacle
or a noxious stimulus. The ciliate does not 'see' the stimulus, but simply
changes its behaviour when it senses a change in its environment.Animation by Rosemarie Arbur. |
Movement
of a lobose amoeba such as Polychaos. This series of images shows how the cytoplasm of an
amoeba extends in the form of (lobose) pseudopodia, leading it in an erratic
path. The cell eventually encounters a particle of food, which it envelops
and encloses within a food vacuole. Animation by Rosemarie Arbur. |
Movement of a vahlkampfiid amoeba - such as Vahlkampfia. This series of images shows how the cytoplasm of an amoeba extends. Animation by Rosemarie Arbur. |
