? Write
two different points between Palaeocolog and Ecology studies 1-
A1/1-Incomplete preservation of
the fossil s record.
2-The ecologist deals with processes taking
place during time spans measured in years.
Palaeo-ecologist has difficulty
recognizing phenomena of this short time in the geologic time instead he
generally works within a framework of thousands or millions of years.
2-How can we get modes of
life Knowledge from Fossils?
A2/By studu the hard parts of Fossils
applied the interpretation of functional morphology.
3-Derscribe each of:?
a-Sessile benthos
b-Nekton
c-Nutrition (microphagous)
d-Asexual reproduction
e-Growth
A3/a.They
are fixed to or sit on the surface or another organism Because they do not move
they are completely under the influence of their environment They are excellent
environmental indicators.
Adaptations of fixed mode
1-by means of spines
2-Or on their shell
3-By
a flexible stalk (plants, brachiopods)
b- Live in the body of the sea
and move in search of food by means of swimming of organs. e.g
-Fins of aquatic vertebrates.
-Funnels ofcephalopods.
-The bodies of animals
adapted to swimming and they have a hydrodynamic profile shapes.
c-Microphagous Organisms
M.Org. eat small nutrient
particles or small organisms
1-Suspention
Feeders.
Nutrient particles in
suspention in the water can be collected in several wayes :
1-By vibrating cilia which
produce water current to direct nutrients towards the mouth e.g Sponge.
2-Byfilter mechanisms e.g
Trilobites.
3-By organisms catching food
and carrying it to the mouth e.g the tentacles of fixed coelenterates.
2-Detritus
Feeders
They eat accumulates organic
matter on the surface of the sediments.
This can be done by D.F in
various waies.
A-grazing by a mouth e.g
gastropods.
B-by the elongation of the
siphon e.g bivalves.
C-Scuffling of the sediment
e.g crustaceans.
D-The movement of their feet
3-Mud Feeders.
Eat the organic .matter which
mixed with sediment by swallowing large quantities of mud or sand
They do re working of mobile
substrate this is called Bioturbation.
1-the microphagous diet is
characterized by the absence of chewable Pieces.
2-Several fixed suspension
feeders have cone shaped shells or skeletons whose opening is orientated
towards the water surface..
d-1-Asexual Reproduction
A.R occurs in lower forms of
life e.g bacteria. In most of portista such as
Foraminifera
altirnates with sexual reproduction.
e- It is possible
to study growth in fossils when we have large populations of given fossils e.g
trilobites, Mollusca.
4-How can
plankton achaived their floating?
A4/1.By a very
small size they are microscopic forms e.g protista
2.By the reduction of
the skeleton e.g Perphorated shell of radiolarian.
3.By expanding the body
(increasing its surface area) e.g some cocolithophorids,acritarchs.
4.By the secretion of
small droplets of oil e.g green algae
5.By high tissue water
retention e.g medusids Psedoplankton.
5-Macrophagous
Organisms?
Eat large food
particles and capture a prey are essential for them.
1-Herbivorse Organisms:
H.O need hard parts in
their mouth to tear up plants this function done:
-by the chitinous jaws
e.g annelids
-by the radula of
gastropods.
-by the jaws of
asthropods.
-by teeth s of mammals.
2-Carnivores Or:
C.O feed on living prey
which they catch it by specialized organs
such as ;
-tentacles jaws of
annelids radula arms of echinoids and teeth of mammals.
3-Saprophages:
S. feed on dead bodies
this is very difficult to determined trat in fossils.
4-Parasites:
Evidence of P.can be
seen in fossils where they have deformed the host or the are found within
tissues.
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