 |
Leptoseris fragilis |
|
Hermatypic corals live in symbiosis
withalgae - zooxantellae. Those
algae, as all algae photosynthetize to
produce energy needed to life. As it is known, in this
process sunlight is necessary
but only with waves 400-720 nm length. Big surprise was discovery
of coral Leptoseris fragilis,
which lives in symbiosis with zooxantellae, but lives on untypical
for reef corals depth between 100 and 150
meters. It seemed, that life on such depth was
impossible for zooxantellae.
No much sunlight reaches this
depth, not enough to conduct photosynthesis, and it contains mainly
waves from 380 nm (ultraviolet) to 500 nm (dark blue) length.
So how it happen, that
this zooxantellae can
photosynthetize?
There were two possible
explanations of the phenomenon:
- First, that algae invented new way
of conducting photosynthesis, so they are able to use waves 380-500
nm length.
- Second, that necessary light is
given in another way.
Researches showed, that the
zooxntellae living in symbiosis with Leptoseris aren’t different from shallow-water
zooxantellae. That means, that the first assumption was
not correct. What
Leptoseris does, that photosynthesis is spossible on such
depth:
- Coral Leptoseris absorbs
light, that reaches to depth 100-150 m.
- Then light pass through coral cell
layers and length of the light waves is
changed. This process takes place, because light pass
along pigmentary cells, which
make fluorescence.
(Fluorescence is a process in which cells absorb light with one
length of waves, and emit light with different length.)
- Leptoseris supplies algae with
light having necessary length of waves.
The description of drawing on the
right:
|
1.
|
|
a cell of entoderm layer |
| 2. |
|
a cell of gastroderm layer |
| 3. |
|
mesoglea |
| 4. |
|
pigmentary cells |
| 5. |
|
zooxantellae |
| 6. |
|
cell nuclei |