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).

Thank you so much for being with

us.

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