By Ms. Azra Arif D.A Degree College for woman Phase VIII
Porifera means pore bearer Early naturalist regarded the sponges as plants because of their frequent branching form and their lack of obvious movement. The animal nature of sponges, first described in 1755, was confirmed in 1765 after observations of their water currents and the movement of their opening. In structure, function, and development, sponges are distinct from other animals Grouped as parazoa – multicellular animals with no well defined tissue Approximately 5000-10,000 species has described which is found in all seas. Mostly are marine but only 150 species are found in the fresh water. They are sessile, and asymmetrical Body organized around a system of water canals and chambers
STRUCTURE Variable like bushy or tree like have finger like projections. Some urn -shaped or shapeless, others shaped are vase like,tube like etc. SIZE Variable within species may vary with age, environmental conditions and food supply. 0.4 inches -6.6 meters. Colour Variable Deep water sponge show neutral or brownish colour Shallow water sponge mostly are bright colour like red orange and occasionally black, some are white.
Types of Cell Sponge cells are arranged in a gelatinous matrix called mesenchyme. Pinacocytes: These cells form the pinacoderm; they are flat epithelial-like cells. POROCYTES :Tube like Open &close the pores Choanocytes :cylindrical or conical cells one flagellum per choanocytes Lined internal cavity
Archaeocytes/amoebocyte Totipotent (transform into other type of cells) Important role in feeding &clear debris that block Ostia sclerocytes secrete spicules. Spongocytes secrete spongin. Collencytes collagen producing cells. Lophocytes secrete lots of collagen but may look like Collencytes. Grey cells act as sponge(immune system) Rhabidiferous cells secretes polysaccrides myocytes that help regulate flow of water
. Types of Skeletons Definition a skeleton is any fairly rigid structure of an animal Skeleton are of two types Endo skeleton Mesenchyme is function as endoskeleton Mesenchyme is stiffened by mineral spicules, spongin fiber or both Spicules made by silica and caco3 Spicules have different shape Simple rods ----three dimensional stars with up to six rays May be separated, joint and fused Spicules patterns are important taxonomic features.
Exoskeleton Some sponges also secrete exoskeletons that lie completely outside their organic components For example sclerosponges ("hard sponges") These exoskeletons are secreted by the pinacocytes that form the animals' skins Exoskeleton is formed by caco3
Water current system Elements include in the water current system 1)ostia; water enters (incurrent system) 2)Choanocytes ( flagellated cells) 3) Osculum (excurrent system ) TYPES OF WATER CURRENT SYSTEMWATER CURRENT SYSTEM Three types of water current /canal system are found in the sponges May be distinguished by arrangement of choanocytes and developmental of canal system.
There are three types of canal systems. Asconoids: Flagellated Spongocoels WATER ENTERS OSTIA SPONGOCOEL OSCULUM OUT All Calcarea are Asconoids: Leucosolenia and Clathrina are examples.
Syconoids Flagellated Canal They resemble Asconoids but are bigger with a thicker body wall. WATER ENTERS INCURRENTCANALS PROSOPYLES RADIAL CANALS SPONGOCOEL OSCULUM OUT. Classes Calcarea and Hexactinellida have species that are syconoid; the genus Sycon is an example.
Leuconoid TYPE Flagellated Chambers These are most complex and are larger with many oscula. WATERS ENTERS DERMAL OSTIA SUBDERMAL SPACES BRANCHING INCURRENT CANALS PROSOPYLES FLAGELLATED CHAMBERS APPOPYLES EXCURRENT CANALS LARGECHANNELS OSCULUM OUT. Most sponges are leuconoid; it is seen in most Calcarea and in all other classes.
Movement fundamentally sessile animals some species can move across the bottom at speeds of 1–4 millimeters (0.039–0.16 in) per day Movements of pinacocytes and other cells(amoeba like) A few species can contract their whole bodies, and many can close their oscula and Ostia.
Feeding Intracellular digestion Filters feeders Phagocytosis(pinacocytes, Archaeocytes, choanocytes) Food particles not larger than 50um Carnivorous sponges Example family Cladorhizidae Extracellular digestion Feed on small crustacean Capture by spicules Completely lost their water flow system and choanocytes
Excretory By diffusion excrete out the nitrogenous waste (ammonia). Respiratory diffusion by individual cells Circulatory Choanocytes create current, amoeboid cells transport food Nervous Cell irritability shown by individual cells, can easily respond against some stimuli like contact chemicals and temp
Reproduction Reproduction are of two types 1)Sexual reproduction 2)Asexual reproduction Sexual Reproduction Most are monoecious with both male and female sex cells in one individual Sperm arise from transformed choanocytes.. In some Demospongiae and Calcarea, oocytes develop from choanocytes; others derive them from archaeocytes. Sponges provide nourishment to the zygote until it is released as a ciliated larva. In some, when one sponge releases sperm, they enter the pores of another Choanocytes phagocytize the sperm and transfer them to carrier cells that carry sperm through mesenchyme to oocytes. Some release both sperm and oocytes into water.
Regeneration and Somatic Embryonogenesis. a) Sponges can regenerate wounded portions. b. Sponge fragments aggregate into new structures, this is somatic embryogenesis. Asexual Reproduction a. External buds are small individuals that break off after attaining a certain size.ex. Scypha b. Internal buds or gemmules are formed by archaeocytes that collect in mesenchyme and are coated with tough spongin and spicules; they survive drought, freezing, etc.
Sponges do not have complex immune system Grey cells play important role Grey cells reject the grafting of foreign material If the intrusions of cells persist they secrete the toxic material that kills all the intruder cells of this area This immune system is activated up to three weeks
Class Calcarea (Calcispongiae). These are calcareous sponges with spicules of calcium carbonate.. The spicules are straight or have three or four rays. Most are small sponges with tubular or vase shapes.. Asconoids, syconoid and Leuconoid forms all occur. Example Leucosolenia Class Hexactinellida (Hyalospongiae). These are glass sponges with six-rayed spicules of silica.. Nearly all are deep-sea forms; most are radially symmetrical. Example hyalonema Class Demospongiae. This class contains 95% of living sponge species.. Spicules are siliceous but not six rayed; they may be absent or bound together by spongin.. All are Leuconoid and all are marine except for Spongillidae, the freshwater sponges. Example euspongia
Evolution Porifera appeared in the early Cambrian period of Paleozoic era. Three classes known in the middle of Cambrian period(Hexactinellida/Hyalospongiae, Heteractinellida, Demospongiae) Heteractinellida are extinct. Calcispongiae appeared in the carboniferous period Paleontology Based on their phylogenetic position, sponges are oldest known animal fossil Late Cambrian period ( 1 st fossil) 900 fossil have described
Sponges have great economic importance and they are both beneficial and harmful to mankind. Beneficial importance By dolphin By human Antibiotic compound Endosymbionts Harmful importance Bore in calm, oysters and barnacles shells and completely destroy them. Example Boring sponge Biochemical aspects Sponges feed on bacteria and other microorganism during the selection of their food they produce substance with antibiotic activity(e.g.ectyonin) Contain great variety of fatty substances e.g. sterols and cholesterol Spongin are formed by scleroprotein which is similar to keratin, found in other animals Accumulate silicon,calcium and considerable amount of other metal