Sponges

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PHYLUM: Porifera 'pore bearing'

Multi cellular organisms - highly adaptive way to increase body size

Heterophoric - feed on organic molecules produced by other organisms.

Structure and Function Collar cells are embedded in a gelatinous (spongy) matrix and supported by a skeleton of needle-like spicules and spongin fibers - elastic proteinaceous fibers

Pores, canals and chambers form a system of water currents one which they use to obtain food and oxygen. - tiny pores ostia are for incoming water and larger openings are for water outlet oscula

Coanocytes - 'collar cells'

Amoeboid cells in sponges are called Archaeocytes - used for phagocytosis and can differentiate into secreting cells and secrete spicules, spongin fibers and collagen.

Pinacocytes are flat cells that line the external surfaces - creating a pinacoderm which helps to keep water out.

No respiratory or excretory organs as these function can occur through diffusion

generally sessile organisms - stationary. But some can crawl slowly

Reproduction - asexual (budding - develops from the outgrowth/bud due to cell division at one particular site) and sexual.

Has specialised cells but not organised tissues or organs

Filter Feeding

Intracellular digestion

Food is drawn into the collar of the choanocytes by the beating flagellum

microvilli move food towards the centre of the body

phagocytised by the cell and passed on the archaocytes (amoeboids) for digestion