•Marine
Protozoans
•Sub kingdom: protozoa of
Kingdom Protista 31,250 species in 7 phyla Features:
•unicellular,
•free living or parasitic,
•mostly solitary though
some colonial (ciliate and flagellates)
•Marine
Protozoans
•move by
•pseudopodia,
•flagella, or
•cilia,
•some amoeba with tests,or
shells,
•ciliates possess a mouth
(cystostome) and nuclei of two sizes,
•reproduction mainly
asexual,
•sexual reproduction in
some groups.
•Marine
Protozoans
•Special marine ones... Subphylum
Sarcodina (including amoeba) produce so-called pseudopodia-flowing
extensions of the cell which can extend one or more at a time (depending what
species) .
•Marine
Protozoans
•Amoeboid marine
protozoans, the Foraminiferans and Radiolarians build cases around themselves.
Forams secrete a calcium (chalky) carbonate shell or test, which resembles a
microscopic snail shell.
Foraminiferans
Foraminifera, or 'forams' as they are often called, are small
marine creatures that build a delicate house (called 'test') from chalk.
Although they resemble molluscs they are in fact single cellular protists, but
they can be quite large for organisms with only one cell. The largest forams
are more than 10 centimetres wide. The pyramids of Egypt are made of stone
cantaining these creatures. The forams in this gallery are up to 2mm. and were
collected from beaches around the world.
•Marine
Protozoans
•Their pseudopod extend
through pores to form a network used to trap diatoms and other minute organisms
suspended in water.
•Most live on the bottom
either free or attached.
•The covering of forams is
potmarked with numerous holes which the pseudopods extend through to capture
smaller ciliates and detritus.
•Marine
Protozoans
•As these die, they sink
to the ocean floor to form ooze which makes up thousands of square miles of the
ocean floor. (white cliffs of Dover are foram tests).
•Marine
Protozoans
•Scientists use the fossil
tests to measure variations in the worlds temperatures as the structure and
sizes of the tests change with water temperature changes.
• Forams living in cold
water have fewer pores than those in warm water.
•Marine
Protozoans
•Marine
Protozoans
•They are among the
largest protozoans with some reaching 100mm but usually .5 to 1.0 mm The tests
are various shapes--oval, tubular, branched, spiral, etc.
• Most shells are multi
chambered consisting of a series of successively larger chambers which are
separated internally with pores or canals connecting them.
•Marine
Protozoans
•The cytoplasm is found in
all the chambers and is continuous through pores connecting the chambers.
•By passing though the
pores of the test, the cytoplasm forms a layer (ectoplasm) over the test which
connects to the endoplasm through the pores. As the animal grows it adds
successive chambers to the initial chamber.
•Marine
Protozoans
•They capture their prey
by means of their pseudopodal network which exhibits active streaming
movements.
• They are found in marine
and brackish water and only a few in fresh.
•A few are pelagic or
sessile but most are creeping bottom dwellers (benthonic).
•Marine
Protozoans
•A third of the ocean
bottom is covered with Globigerina ooze, made mainly of the accumulation of the
tests of this common foram. (usually in water under 4000 m deep because tests
dissolve in the high concentration of CO2 in deep water.)
•Good fossils are
important in detecting oil bearing strata.
•Marine
Protozoans
•Radiolaria (Subclass)
Radiolarians form a glass like test composed of silica which is studded with
long transparent spines to increase buoyancy and ward off predators.
•Typical shells are
spheric with radiating spines though the structure varies...thin needlelike
pseudopod capture food.
•Marine
Protozoans
•The radiolarians also
form ooze, though radiolarian ooze and is usually found deeper being able to
resist more pressure than the calcium carbonate foram tests.
•Marine
Protozoans
•Ciliates are some of the
protozoans that use cilia for locomotion. ..creeping over the bottom, living in
gills, attached etc.
•The Tintinnids build
their own quarters that drift in the water.
•Marine
Protozoans
•Reproduction is usually
asexual binary fission whereby each effort results in two identical daughter
cell (MITOSIS).
•This occurs when
conditions are favorable...warm, lots of food etc.,. but sexual reproduction
can occur in some when adverse conditions (drying up) occur as a survival
method.
•Marine
Protozoans
•The forams have
alternation between sexual and asexual generations, having asexual reproduction
to produce many organisms which secrete shells around themselves and when
mature, they produce identical gametes which are liberated into the sea and
fuse in pairs to produce individuals which in turn secrete a shell grow to
maturity and repeat the cycle.
•Marine
Protozoans
•Life cycles are known for
a few foraminiferans.
•They have two phases, one
asexual and the other sexual.
•They are also dimorphic,
having two types of individuals in each species, based mainly upon the size of
the initial chamber (proloculm) of the test.
•Marine
Protozoans
•Ecology
Its complex as it would be for organisms found in every environment.
•They occur commonly in
plankton...benthic communities, marine depths (13,000 ft for a foram) and since
many protozoans exploit bacteria as a food source, they form part of the
decomposer food web in nature.
•Marine
Protozoans
•It is thought that they
stimulate the rate of decomposition by bacteria by grazing on bacteria and keeping
the bacteria community in a state of physiological youth and hence at the
optimum level of efficiency.
•Ciliates can cause
illness in some organisms.
•Marine
Protozoans
Invertebrates
•Early invertebrate
records are scarce because of the lack of fossil evidence until about 570
million years ago (Cambium) when organisms with external skeletons appeared.
•All phyla that had hard
outer parts existed 530 million years ago and many soft bodied animals
belonging to modern phyla of worms appeared as well.
Invertebrates
•During the jellyfish-worm
stage of animal evolution, the various basic designs of animal bodies evolved.
First came the jellyfish, a blind sac with only two layers of cells and a
single opening serving as both mouth and anus.
Invertebrates
•They have radial
symmetry, meaning they have no front or hind end which is adaptive to only two
types of habitats...floating on the surface of the sea or attached in an
immobile position on the ocean floor.
•Great masses of jellyfish
cover wide stretches of the ocean and corals and sea anemones line tide pools
in warm waters.
Invertebrates
•The jellyfish phyla are dominant in these habitats and while
their basic body plan adapts them admirably to certain ecological niches, it
severely limits their options for colonizing others.
•This body plan was also
successful in flatworms but nowhere reached the dominance of the body plan of a
tube within a tube design.
Invertebrates
•There are three plans,
bilateral symmetry, a diversity of tissues and organs, spaces or body cavities
(coelom) filled with fluid and a fourth modification is characterized by radial
symmetry found in sea stars etc.
Invertebrates
•What do crabs, sea
urchins, worms, corals all have in common? they have NO backbone and are all
invertebrates. Over 95% of all known animals are invertebrates. Their forms
range from the microscopic amoeba to giant squids 59 ft. long, inhabit all
regions of the world and all have a marine representative.
Invertebrates
•SPONGES
•Phylum Porifera..(pore-bearing). 5000 species of 790
genera...worldwide distribution, fresh and marine. (120 species in Keys!) Size
microscopic to 2m
•Sponges..animals with
many pores, without definite form of symmetry, and do not contain organs or
true tissues. They are all sessile.
Invertebrates
Invertebrates
•The humble bath sponge,
used for centuries particularly in the Mediterranean region were originally
thought of as plants but are now considered animals (only in 1765)(even its own
subkingdom ..Parazoa) They probably originated from flagellated protozoans or
primitive metazoans. They are the simplest of multicellular marine animals.
Porifera
•The humble bath sponge,
used for centuries particularly in the Mediterranean region were originally
thought of as plants but are now considered animals (only in 1765)(even its own
subkingdom ..Parazoa) They probably originated from flagellated protozoans or
primitive metazoans. They are the simplest of multicellular marine animals.
Porifera
•Their colors though are
beautiful, Orange, yellow, green, purple, violet or scarlet or rich brown and
have survived millions of years without even moving.
Porifera
•Size range from micros.
to 2m, form thin incrustation on hard surfaces to which they attach, others are
massive tubular, branching, urn- or cup- or fan- shaped (amorphous).. Colors
range from drab to brightly colored.
Porifera
•The sponges single
purpose in life is to pass water through itself, the water yielding food and
oxygen, minerals, and carrying away waste products. The sponges are unchanged
since they evolved and were ancient 300 million years ago and appear to be
natures orphans
Porifera
•They are so poorly organized that they are not even included
in the direct line of animal evolution.
Porifera
•Rachel Carson wrote that
"nature seems to have gone back and made a fresh start with other
materials" with no evidence of any relationship between them and
coelenterates, leaving sponges in an evolutionary blind alley.
Porifera
•Structure.. most are
similar in structure, simple body wall containing cells and connective tissues
and cell types like amoebocytes which wander through the inner tissue secreting
and enlarging the skeletal spicules and laying down spongin threads.
Porifera
• Most have a skeleton of spongin, elastic,
but resistant fibers of protein which may be the only means of support but can
be found together with spicules.
Sponges, like
all animals, possess some sort of a skeleton that gives their bodies shape.
As a whole,
poriferans have diverse skeletal elements including calcareous laminae, organic
filaments, and siliceous and calcareous spicules. The skeletons of each of the
major poriferan groups are distinctive and have been used to reconstruct their
evolutionary relationships.
Spicules come
in an array of beautiful shapes, as seen in the SEM images to the left.
These images
were obtained using UCMP's
Enivronmental Scanning Electron Microscope.
Spicules are often categorized by size, the larger being megascleres and the
smaller microscleres. Some spicules are formed of the mineralized substances
calcium carbonate and silica, while others are made of an organic substance
called spongin.
Spongin
skeletons were and are used as scrubbers in bathtubs, though they are fairly
expensive. The ubiquitous bathtub accessory called a lufa is NOT a sponge, but
a plant. The mineralized forms are considerably more hard and are not as
frequently used for commercial purposes.
Porifera
•The internal skeleton can
be made of hard rod or star shaped calcareous or siliceous spicules, the shapes
genetically determined for each sponge, and/or the meshwork of protein fibers
called spongin (bath sponge) which is similar to silk and the horns of many
animals.
Porifera
•Sponges are filter
feeders straining off bacteria and fine detritus from the water. O2 and
dissolved organic matter are also absorbed and waste materials are carried
away. Water is pumped inward through small pore cells into the inner chambers
lined by flagellate cells called collar cells.
Porifera
•They ingest the food particles and water is expelled through
the sponges surface through the osculum.
•Reproduction can occur asexually by budding off new materials,
by fragmentation in which parts grow into new sponges, and in sexual
reproduction, eggs from amoebocytes and sperm from collar cells (or
amoebocytes) usually at different times within the individual.
Porifera
•Sperm is shed into the
water but eggs stay in the sponge and is fertilized there. This is called
spawning. A larva (amphiblastula) may be produced, swim for a few days and
settle changing into colonies. Some Antarctic sponges (mature) have not grown
in over 10 years.
Porifera
•Classification...because
they adapt to their environment their shape is of no help to identify them so
they are classified by their skeletons, "lime sponges, glass sponges, and
fibrous or horny skeletons.
Porifera
•Ecology. Sponges live on
a firm substratum, vertical range from intertidal to 27,000 ft (one fresh) and
the intertidal are seldom exposed to air for any time.
• They are eaten by sea
slugs (nudibranches) , chitins, sea stars, turtles, some tropical fish
Porifera
•Usually more than half
the exposed species are toxic to fish. The toxins not only prevent predation
but keep the surface of the sponge clean of animal larva and plant spores from
settling on them and may prevent neighboring invertebrates from overgrowing and
smothering them.
Porifera
•Sponges contain
antibiotic substances, pigments, chemicals like steroids, toxins,
anti-inflammatory, and anti-arthritis compounds. Boring sponges (Cliona)
weakens oyster shells, and damage and weaken tropical stony corals excavating
chambers by chemical and mechanical methods.
Porifera
•On reefs some weaken,
while some bind skeletons together, some protect undersurface of coral from
attacks by boring organisms and are most successful under low light.
Other..sulfur sponge is able to dissolve seashells into calcium and accounts
for conversion of shells to sand on the ocean
Porifera
•Loggerhead sponge, shaped
like barrels, host up to 12,000 pistol shrimps and other creatures. The sea
orange wraps itself around a hermit crab shell, obtaining transport in exchange
for the camouflage and Neptunes Cup grows out of the sea floor in the shape of
a goblet.
Porifera
• done