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Made by Abhishek RaiMade by Abhishek Rai
MesophytesMesophytes
XerophytesXerophytesAquatic AnimalsAquatic Animals
Aquatic AnimalsAquatic Animals
Grazing, Pollution, and Evolution
c. They hatched the eggs and tested their abilities to eat the toxic cyanobacteria.
Daphnia swimming amid toxic cyanobacteria in Lake Constance
b. Nelson Hairston et al. collected Daphnia eggs in a state of diapause from the sediments, layer by layer
a. pollution over the past 30 years has caused a proliferation of toxic cyanobacteria in Lake Constance
B. Filter Feedingaquatic animals, sessile benthic invertebrates: sponges, barnacles, polychaete worms, bivalves, etc. constant flow of water through organism – constant supply of microbes suspended in the water column microorganisms filtered through gills, tentacles, mucous nets microbes are autotrophs, heterotrophs, detritus sea squirts (tunicates, ascidians) and bivalves can capture particles as small as viruses
tunicates, so named because the outer layer of the body wall is a tough "tunic", made of a substance that is almost identical to cellulose animal consists of a double sac with two siphons: Sea water is pumped slowly (by cilia) through one siphon, sieved through the inner sac for plankton and organic detritus, and the filtered seawater is pumped out again through the second siphon, the atrium. Ascidian Tunicates are called sea squirts because when taken out of the water they squirt the water inside their body with force through the atrium
Clavelina, a group of transparent sea squirts
Ciona, with two siphons
Apterostigma garden
Worker ant carryinga piece of fungus
B. Ambrosia beetles and wood-degrading fungi
cellulose monomer animal biomass
III. Cellulose digestion – key process in animal/microbe mutualisms cellulose – most abundant carbohydrate in the biosphere– chain of glucose molecules linked together – most animals can’t degrade it– rely on cellulolytic microorganisms
microbial biomass
degradation products
1. coprophagous and detritivorous animals (above)
2. animals that cultivate microbes externally
3. intestinal symbionts
IV. Cultivation of Microorganisms (External), plant-eating insects:
A. leaf-cutting ants
mutualism – ants – excavate cavity in soil bring leaves to fungus inoculate leaves w/fungus fungus grows by decomposing cellulose ants eat fungus cellulose --> fungal biomass --> ant biomass
also, when ants eat fungi, the acquire cellulase, so they are able to continue degrading cellulose in their guts, using enzyme produced by the fungus
obligate mutualismfungal garden breaks down without ants ants protect fungus from competitorsfungus requires ants for dispersalants require fungus for food
XEROPHYTES
•Stomata sunken in pits creates local humidity/decreases exposure to air currents;
•Presence of hairs creates local humidity next to leaf/decreases exposure to air currents by reducing flow around stomata;
•Thick waxy cuticle makes more waterproof impermeable to water;
Xerophytes possess some or all of these adaptations to prevent excessive water loss
Xerophytes possess some or all of these adaptations to prevent excessive water loss cont.
•Stomata on inside of rolled leaf creates local humidity/decreases exposure to air currents because water vapour evaporates into air space rather than atmosphere e.g. British Marram grass
•Fewer stomata decreases transpiration as this is where water is lost;
Adaptation How it works Example
thick cuticle stops uncontrolled evaporation through leaf cells
small leaf surface area
less surface area for evaporation
conifer needles, cactus spines
low stomata density
smaller surface area for diffusion
sunken stomata maintains humid air around stomata
marram grass, cacti
stomatal hairs (trichores)
maintains humid air around stomata
marram grass, couch grass
rolled leaves maintains humid air around stomata
marram grass,
extensive roots maximise water uptake cacti
Xerophyte adaptations summary:
All Cacti are xerophytes
Left and right Epidermis of the cactus Rhipsalis dissimilis. Left: View of the epidermis surface. The crater-shaped depressions with a guard cell each at their base can be seen.Right: X-section through the epidermis & underlying tissues. The guard cells are countersunk, the cuticle is thickened. These are classic xerophyte adaptations.
Transverse Section Through Leaf of Xerophytic Plant
XEROPHYTESPECIES STUDY:
MARRAM GRASS
Marram grass possesses: rolled leaves, leaf hairs and sunken stomata. These adaptations make it resistant to dry conditions and of course sand-dunes which drain very quickly retain very little water.