If not otherwise stated
in the caption the microscopical pictures
were taken through the 100x HI objective.
raining in Cancún. The rainy season has started and it is now
time to hunt
for ….. tree holes. Where a branch had fallen or has been cut; many
times a more
or less deep hole develops. It is a cup waiting for the rains.
or perhaps more months the hole has received dust and leaves, or other
that was contributed by the wind, including the cysts and spores of
things. Now the rain fills in the hole with neutral or acid water, in a
were all natural water is hard. (Over
opportunity to see if there is something living in those special
tree hole is no more than twenty meters from my house were a young
tree was pruned to allow only one stem to grow. With
time at 30 cm from the ground an oval hole with 25 x
15 cm diameter
has developed with a depth of 6 cm.
ago it was dry with a consolidated earthy bottom and some small leaves
is filled with rainwater. And the water looks a little muddy and with a
superficial film of bacteria. It is an invitation to see the initial
fauna of a
recently flooded tree hole (fig. 2 above).
With my “sampler” (a little ladler) I took more
or less 50 ml of water, and a very little sample of dirt from the
I install in a 100 ml cylindrical flask for a couple of hours before
- stained with Gentian Violet.
- showing the density in a typical sample. Obj. x4
immediate exploration of the superficial and intermediate waters shows
of bacteria (mostly bacillus rods and some spirillum) and an
population of flagellates that swim at a velocity that made it
to shoot even
one in-focus picture. To show the density of the population I only had
to adding a drop of GALA, to
definitely stop the out of control
also permits a better understanding of its
morphology and permits us to assign the majority of the population to
flagellate of the genus Astasia.
Astasia Ehrenberg 1838,
is a small
flagellate, of extremely
fast movement, which reached great densities in this culture. We can
in fig. 3 taken with the 10x objective.
see its morphology in more detail I must use at least a magnification
which requires the immersion objective, a very thin preparation and a
coverslide solidly fixed with a sealant. I used nail polish varnish.
swimming Astasia appears fusiform,
with the anterior
end more or less blunt, and an acute caudal end (fig 3).
the anterior end there is one short invagination of the pellicle
(canal, or reservoir)
erroneously denominated in English as the "gullet". When some euglenoid
ingest foods, (like Peranema, by ex.) they do it
generally with a
temporal buccal opening, or one that is permanent and
provided with reinforcing rods
placed outside and below the canal.
alive (at right) and a big specimen fixed with GALA at left
reservoir provides space and protection for the insertion of the
Astasia species are
practically colorless, because they do not
chloroplasts like Euglena nor do they
possess euglena's characteristic red stigma generally found
in the base of the reservoir.
position of the reservoir allows the differentiation of two subgenera
These are Euastasia and Euglenoidea. The population in
hole, by the apical position of the reservoir (fig 4)
and the flagellum, belong to the subgenus Euastasia
Christen 1963. In the
Christen 1963, the reservoir and therefore the emergence of the
subapical, as it occurs in Euglena.
(Euastasia) klebsii -
extended and fixed individual, and two
Alive, the most
remarkable anatomical elements, aside from the flagellum are
the large contractile vesicles located next to the flagella
and the grains
of paramylon that tend to group itself at the rear. Paramylon
complex carbohydrate that is easily recognized because it does not give
typical bluish black coloration of the starch, when tested with iodine.
that live in the substrate, or even some swimming ones, show a typical
called "euglenoid movement" that consists of a local expansion of the
cell, shaped like a knot, which moves up and down throughout the cell.
it is shown spontaneously in cells that have rejected its flagellum,
initiate the euglenoid movement by adding to the drop with the
small drop of fixative. Irritation causes the movement.
with euglenoid movement the grains of paramylon tend to
themselves in the posterior end, which in these cases is spherical.
is only visible in favorable individuals, and it is not very often well
The size of
individuals varies of course with their contraction state,
from 30 to
40 micrometers in individuals in normal swimming (fig 3) up to 60-65
in totally extended individuals (fig 4). The flagellum is at least one
half times as long as the swimming cell, and the grains of paramylon
cylindrical rods barely 3.5 to 4.0 micrometers in length with a
1.5 to 2.0 micrometers. The nucleus has an average diameter of 6
previous description and the captured images are consistent with the
klebsii Lemmermann 1910.
effect of asphyxia.-
if one leaves alone a sealed preparation for some minutes the
to the lack of oxygen in a quite homogenous form. They shed the
they adopt a shape that goes from an ellipse to a sphere. This is a
state called palmelloid, that generally is completed by the secretion
mucilaginous sheet, which allows the protist to subsist until finding
itself again in favorable
conditions. They accumulate paramylon in the posterior end and the
spherical nucleus is clearly visible in
preparations fixed with
GALA, with a large endosome and a granular content (fig.4).
Khawkinea Jahn & McKibben
day of harvesting, the population was formed by myriads of small Astasia
But after three days in the laboratory, the dominance
to a somewhat bigger species, wider and with a more tapered shape, Khawkinea
Khawkinea has a subterminal (lateral) reservoir,
in a position similar to the one of Euglena, and it also
has one red
colored ocular spot (stigma). Its only difference with the
that it does not have chloroplasts. In laboratory experimental
can be induced to shed its chloroplasts, and those individuals are
distinguished from a Khawkinea.
|Fig. 5 - one Khawkinea
and one recently fixed. Notice the red ocular spot and the subterminal
position of the flagellum emergency point. In the left picture the
canal can be seen.
this species more easily I added to a 1 ml sample 10% of Rhode’s
fixative which induces the sedimentation of the suspended specimens, be
ciliates, and gives them a mostly brown color.
of a typical specimen is around 45 micrometers, with a flagellum at
same length, and even longer. In the fixed individuals the nucleus
measures 7 mic., and
of paramylon taken at random measured 5 x 3 mic.
individual stigma (fig 5, right) is seen in front view, and this
allowed the measurement of its
diameter which was 2.2 mic. As the stigma is always found at the bottom
of the flagellum
the measurement from stigma to the flagellum point of emergence gives
estimation of its length, which turns to be near 9 mic.
|Fig. 6 - A Khawkinea, fixed
images to show the entire flagellum length.
the pictures the iodine present in the Rhode’s hasn't colored blue any
the specimens, or when these die by asphyxia they contract and adopt a
racket shape. Generally dead individuals have shed the flagellum,
of Rhode’s fixed ones show it very well (fig. 6). The high density of
prevent the nucleus or the contractile vacuole to be seen.
one preparation appeared one lonely individual of a phototrophic
flagellate. It was a species of Euglena
of 100 microns
length, with small chloroplasts and cigarette shape. Perhaps it was the
announcement of a future change in the population.
from the surface.
lower density (only one or two individuals to each two or three
preparations) appeared what I think are two species of Dileptus, a large and narrow one (Dileptus
sp.1), and another smaller but wider one (Dileptus
sp. 2). When little drops of fixative
to stop them, the individuals rounded up and edematized. (fig. 7). Only
individuals fixed with
Rhode's maintained a
suitable morphology which allows them to be shown in a picture.
|fig 7 - bad reaction to
near the surface below the bacterial
veil. It swims impelled partly by his cilia, but extending its long
neck and waving
it in a helical manner (akin to the movement of a flagellum) while
the water as they advance. This movement allows us to easily
genus from Amphileptus, of very similar aspect, but of
and rigid neck. In the base of the Dileptus neck a
great mouth is
oriented forwards, circular and reinforced by trichites that turn it
| The smaller but wider
species measures 200 to
250 micrometers of length with a maximum width of 50 to 58 mic. In the
photographed individual the neck represents 32 to 40% of the total
and narrowest species the corresponding measures were: Total length 330
maximum width 35 to 39 mic. Neck/total length 40-48 %. The proportion
to total length was 10-12% in the narrow one and 20-24% in the wider.
Measurements were taken on pictures
individuals, swimming normally, that cannot be reproduced here because
movement of the protists doesn’t allow sharp enough images to be
have a thick and long macronucleus which seems to be built of two
displaced one with respect to the other.
bottom and its inhabitants. The
accumulated sediment in the bottom showed it is composed fundamentally
by ejections of previous inhabitants. By its form and size they seem
to be faeces of some mosquito
species. (fig. 9)
Amongst them they teem Khawkinea, and also exists an
population of one small Vorticella with annulated
with a hardly 40 mic. chalice length (fig.
appearance, estriation and position of the nucleus it seems to be V.
Kahl, 1935 (You can see
illustration in pag. 724, fig. 9 of Wimpertiere oder Ciliata, on-line
water immediately in contact with the sediment it moves with enormous
executes true zigzag jumps, (bouncing like a ball it is said sometimes to resemble)
abundant population of Halteria
spectacular small ciliate,
with a diameter not greater than the length of the flagellates.
|Fig. 8 - a big individual
of the Dileptus
|fig. 9 - another Dileptus
sp 2, labelled
like Dileptus, this species is impossible to photograph
without the aid of
an electronic flash. Nevertheless Halteria is fixable in
an acceptable shape by means of Rhode’s fixative. Although the
distorts a little the ciliation in fig. 11,
easily recognizable are the Adoral Zone of Membranelles, its Macronucleus and the Equatorial
Stereocils that allows its acrobatic antics.
10 - detritus in the
bottom of the tree-hole. obj. x 4. Dark stop 12 mm
||fig. 11 - remains of
arthropoda in the bottom detritus.
x 4 obj.
from the evidence of the existence of dipteran larvae commented above,
between the bottom sediments, fossil-like remains of other previous
a small Centropyxis and the remains of 2 bdelloids,
of all content except for trophi. From the three fingers of the foot
of spurs it seems to belong to the genus Rotaria.
12 - Halteria grandinella. Fixed with Rhode's.
13 - Vorticella cupifera alive.
days after its first filling, our tree hole of 15 x 21 cm with 6
cm of depth, supports an enormous and diverse bacterial population,
flagellates and four ciliates. Both flagellates do not have
mouth, nor other elements for the capture of particulate food, and they
to be osmotrophics.
Along with the bacteria, they exploit the
abundant dissolved organic and inorganic matter the rainwater extracted
the existing bottom sediments of the tree hole.
14 - remains of a
bdelloid rotifers in the bottom detritus
x 40 obj.
15 - the shell of a
Centropyxis in the bottom detritus
x 40 obj.
Euglena is obviously phototrophic,
although it can also participate with the absorption of dissolved
the ciliates are all heterotrofic. Vorticella and Halteria
they are bacteriophages and microdetritivores.
Dileptus is considered a predator. Being no other
visible prey we must consider that they consume the so abundant
Halteria. But I did not see them in any capture activity, nor do its
reveal digested Khawkinea remains.
Its enzymes must be really active.
mystery of the tree-hole populations is the time at which reproduction
place. I have examined dozens of slides
day around but none at night. In none did I see any individual of any
species divide. But the populations of all of them are not only