Observation Descriptions
Observation Descriptions on Hydra viridissima
Hydra viridissima Pallas, 1766
Hydra viridissima in a Freshwater Aquarium
Hydra viridissima living amongst Java moss (Taxiphyllum barbieri) filaments in a freshwater aquarium.
Fig. 1: Hydra viridissima. Penetrant nematocysts (arrow), ejected sticky thread of a gultinant ptychocyst (double headed arrow). |
Fig. 2: A closer look at the tentacles. The optical cross section shows three types of their cnidae: some penetrant nematocysts (arrow) showing shaft and coiled hollow tubule for transportation of the toxin into the prey, some more volvent spirocyst (arrowhead) and one glutinous ptychocysts (double headed arrow). |
Fig. 3: In the Hydra body. Nucleus of a zoochlorella (arrow), glutinous ptychocyst for attaching the animal to a surface (double headed arrow).
Scale bar indicates 10 µm.
The zoochlorellae
Some species of coccoid green algae live as symbionts (zoochlorellae) in the cells of many single-celled species from groups such as the amoebae, the ciliates or the foraminifera. However, zoochlorellae are also known in animals such as freshwater polyps, other groups of coelenterates, in freshwater sponges, turbellarians, etc. These symbioses are generally mutually beneficial, the hosts benefit from secreted assimilates of the algae, and the algae are better protected from grazing due to the size of the hosts.
When the hosts lack food, part of the zoochlorellae is usually digested.
Fig. 4: Chlorella vulgaris as symbionts in Hydra viridissima. Nucleus (arrow), cup shaped chloroplast (double headed arrow), oil droplet (arrowhead).
Scale bars indicate 5 µm.
© Wolfgang Bettighofer,
images under Creative Commons License V 3.0 (CC BY-NC-SA).
For permission to use of (high resolution) images please contact postmaster@protisten.de.
New items
nostochinearum
subgranulatum
spec.
komarekii
arboricola
viridis
fenestrata
tripus
subspicatus
strictissimum
arcuata
sculpta
aureus
lunaris
lunatus
rostrata
bibraianum
irregularis
ehrenbergianum
reticulatum
marssonii
tetras
enorme
spec.
obesa
parva
dimorphus
limneticum
falcatus
viridis
cystozygote
gracillimum
hemisphaerica
lagerheimii
sicula
sudetica
aciculiferus
simplex
elegans
cyst
caudatum
pisiformis
angustum
tetrachotoma
simplex
var. sturmii
superbus
triappendiculata
spec.
incus
biradiatum
spec.
zoospores
mutabilis
spec.
microporum
var. octaedricum
tetrapedia
braunii
speciosa
reinhardtii
vulgaris
communis
pusillum
boryanum
var. longicorne
dissectum
lacustris
confluens
opoliensis
var. carinatus
quadrisetum
purpureum
paludosa
speculum
diaphanum
helminthosa
New items
nostochinearum
subgranulatum
spec.
komarekii
arboricola
viridis
fenestrata
tripus
subspicatus
strictissimum
arcuata
sculpta
aureus
lunaris
lunatus
rostrata
bibraianum
irregularis
ehrenbergianum
reticulatum
marssonii
tetras
enorme
spec.
obesa
parva
dimorphus
limneticum
falcatus
viridis
cystozygote
gracillimum
hemisphaerica
lagerheimii
sicula
sudetica
aciculiferus
simplex
elegans
cyst
caudatum
pisiformis
angustum
tetrachotoma
simplex
var. sturmii
superbus
triappendiculata
spec.
incus
biradiatum
spec.
zoospores
mutabilis
spec.
microporum
var. octaedricum
tetrapedia
braunii
speciosa
reinhardtii
vulgaris
communis
pusillum
boryanum
var. longicorne
dissectum
lacustris
confluens
opoliensis
var. carinatus
quadrisetum
purpureum
paludosa
speculum
diaphanum
helminthosa