Clear concept Of porifera phylum
Transcript of Clear concept Of porifera phylum
Presentation on
Phylum Porifera
Presented by:
Md. AshrafulIslam
Md. HumayunKabir
WHAT IS PORIFERA
Porifera, a phylum within the Kingdom
Animalia, is commonly refered to as sponges.
The sponge or poriferans, named from Latin
porus “pore” and ferre “to bear”, believed that
they are the simplest animals on the earth
because they have not true tissues such as
muscles, nerves, and internal organs. So
many scientists who study this animal
separated them from other Metazoans to
phylum of the Parazoa branch of Kingdom
Animalia.
Definition of Porifera
The Porifera may be characterized
as a sedentary, aquatic, mostly
marine, solitary or colonial, radially
symmetrical or asymmetrical,
multicellular organisms; without
definite organ systems, mouth and
nervous tissue; with a pores, canals
and chambers through which a water
current flows.
Example of Porifera
Example of Porifera
General characterastics
# porifera are aquatic, mostly
marine animals.
# They are solitary or colonial.
# Body is radialy symmetrical or
asymmetrical and multicellular.
# Their body bears a lot of pores
which called ostia.
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# Body shape is cylindrical,
branching, vase like or globular.
# They have no definite organ
system like as mouth and
nervous tissue.
# Respiration occurs through the
osculam or oscula with the
current of water.
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# reproduction both asexual or
sexual. Asexual reproduction by
means formation of buds and
gemmules.
# Sexual reproduction by means of
ova and sperms.
# Fertilization is internal and
cleavage holoblastic.
Classification of Porifera
Porifera classify upto 3 classes on the base of skeleton type
1. Class Calcarea : Have a skeleton of separate
calcareous spicules(monoxon or tetraxon)
Solitary or colonial
Body shape is base - like or cylindrical
Canal system asconoid, syconoid or leuconoid
Example: Leucosolenia
2.Class Hexactinellida:
Called glass sponges
Body shape cylindrical or funnel
No epidermal epithelium
Choanocytes line finger shaped
Example: Hyalonama
3. CLASS Demospongiae:
Larged sized, solitary or
colonial
Skeleton may be spongin fiber
Canal system leucon type
Example: Oscarella
Representative of Porifera
sycon Systematic position:Phylam :porifera
Class :calcareaOrder :Heterocoela
Family :SycettidaeGenus
:scypa(=sycon)
Some types of sponges:
General characters:
*Pore bearing ;asymmetrical or symmetrical.
*Skeleton consist of calcareous spicules.
*canal system syconoid type.
Habits and habitats: Scypa formerly called sycon or grantia is widely
diatributed with numerous species. It is a small marine sponge found permanently attached to submerged rocks and other solid substratam,inshallow waters near the coast,just below the low tide mark.It is a branching,colonial sponge,thoughsolitary individuals are also found.
Canal system of sponges
Three types of canal system of sponge:
1. Asconoid:
Simplest, radially symmetrical, vase like body.
Body wall composed of an outer and inner epithelium with a mesenchyme.
Mesenchyme contains skeletal spicules.
The wall is perforated by numerous microscopic aperture which called ostia.
Each pore is intracellular.
Water current impelled by the flagella of the choanocytes passes through the incurrent pores into the spongocoel and out through the osculum
Flow chart…….
Water current from exterior
ln current pores spongocoel
osculum water out.
Example:Leucosolenia
2. Syconoid:
First stage above the asconoid type. IT IS FOREMED BY THE out pushing of the wall of an asconoid sponge at regular interval into finger like projection called radial canal. At first these radial canals are free projection and the outside water surround their whole length, for there are no definite incurrent channel. But in most syconoidsponge, the wall of the radial canal fuse in such a manner as to leave between them tubular spaces, the incurrent canals, which open to the exterior between the blind outer ends of the radial canals by apertures termed dermal ostia.
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The water current in syconoid sponges takes
the following route:
Dermal pores lncurrent canal
prosopyles radial canals lnternal
ostia
spongocoel osculum out.
Example: Scypha
3. Leuconoid:
The main characteristics of the leuconoid type of canal system are the limitation of the choanocytesto small chambers, the great development of the mesenchyme, and the complexity of the incurrent and excurrent canals. The course of water current is dermal ostia lncurrent canals prosodus(if present) prosopylesflagellated chambers apopylesaphodus(if present) excurrent canals larger channels oscula out.
Example: Oscarella
General Morphology
The body of a simple sponge may be
compared to a vase, attached at the base,
open at the top, and with the wall perforated by
numerous canals opening externally as ostia.
The canals open into a central cavity, the
spongocoel, which itself opens through the
osculum at the top of the organism. Although
the sponges have very simple internal
structure that consist of soft parts and hard
parts (Skeleton).
Soft parts
Porocytes, Flat epidermal cells, and Amoebocytes. The wall of a sponges have two layaers of cells. The outer layer, epidermis or The cellular part of the sponges body consist of Choanocytes, ectodermis, is composed of a single layer of thin, flat cells. It’s seems to function chiefly as a protective covering. The inner layer, or Flat epidermal cells, lines the spongocoel and chambers and parts or the whole of the canals in the wall. It is consists of
It is consists of Choanocytes or collar cells, which have a collar surrounding the flagellum, are both the food-gathering cells and the pumping cells of the water circulatory system that operate through central cavity (cloaca or spongocoel) which opens at the top to the osculum . Porocytes are tubular cells that make up numerous tiny holes outer surface of the sponge known as ostia or dermal pores. Amoebocytes(live between the choanocytes and the epidermis) carry out many of the sponge’s functions such as transport of nutrients, secretion of the spicules, and production of gametes.
Hard parts – Skeleton
Some sponges have not skeleton because
their body may be composed of a simple
colloidal jelly but most of sponges have
material consists of calcareous, siliceous, or
hard organic spicules. The skeleton is
secreted by spicules that can be grouped by
size, number of axes, and number of rays.
Size: 1. Megascleres - large spicules 0.1 mm
to over 1.0 mm long. These may fuse to form a
coherent framework.
2. Microscleres - small spicules 0.01 mm to 0.1
mm long. These are scattered all over the
body.
Axes: 1. Monaxons - one axis
2. Triaxons - three axes
3. Tetraxons - four axes
4. Polyaxons
5. Desmas
Rays: 1. Monactine - one ray 2. Diactine - two rays 3. Triactine - three rays 4. Hexactine - six rays 5. Polyactine - Multi-rayed (Lehmann, 1983
Reproduction
The reproduction of sponges exhibits many characteristics of sessile or slow-moving animals. Asexual reproduction is quite common, and occurs in one of two ways:
1.)Fragments that break off from the parent animal may become new sponges
OR,
2.)Gemmules: collection of amoebocytes within a hard, protective outer layer.
Sexual reproduction
in sponges is highly specialized. The simplest and most primitive form of fertilization is external, with the sperm and egg cells shed into the water. However, in most sponges, fertilization is internal. The sperm cells are carried by the water currents out of the osculum of one sponge and into the interior cavity of another sponge. There they are captured and transferred to ready eggs. Most sponges even provide a certain amount of maternal care, retaining the toung during the early stages of development. The embryonic (not
full grown, still developing) sponge develops into a free-swimming larva that locates an appropriate site, settles and attaches, and develops into an adult sponge.
Most kinds of sponges are hermaphrodites, meaning the same individual has both male and female reproductive structures and produces both sperm and egg cells. This is a great advantage for animals with little or no motilitty, as a hermaphrodite can mate with any partner, with no limitations concerning gender.
Sponges are very interesting and unique, with many different and beautiful species. For a much more detailed
Ecology
Sponges are ecologically variable and adaptable. Sponges mostly living in marine which can be found attached to surfaces anywhere from the intertidal zone to as deep as 8,500 m. Some species adapted to freshwater environment. Modern calcisponges, demosponges, and sclerosponges mostly occupy shallow water. Calcisponges are usually found in water less than 100 meters, whereas sclerosponges can be found to 200 meters. Hexactinellids are restricted to deeper water (Rigby, 1987). Most sponges are sessile so they feed by filtering out of the water plankton and other suspended organic material (Dodd, 1981).
Geological distribution
Sponges are worldwide in their distribution, and range from waters of the polar regions to the tropical regions. In the Paleozoic and Mesozoic, shallow-water sponges were important reef builders. Demosponges were vital frame builders in reefs of North America, Europe and Australia throughout the Ordovician, Silurian, Devonian, Permian, and Triassic. Hexactinnelids were important frame builders in Jurassic reefs of Europe. Sclerosponges of the Paleozoic and Mesozoic were also associated with reefs. Calcisponges also contributed to Permian and Triassic reef complexes of North America and Europe (Rigby, 1987).
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