Phylum - Porifera

Explanation

(i)These animals are with simplest body plan and are called as 'Sponges'. They bear numerous pores on their body. Those pores are called as 'Ostia' and 'Oscula'.
(ii)These are aquatic animals and most of them are marine, few are fresh water dwellers.
(iii) Most of the animals have asymmetrical body.
(iv) They have special type of cells called collar cells'.
(v) They are non-motile, attached to a solid support. Hence, referred to as sedentary animals.
(vi) Their spongy body is supported by spicules or spongin fibres. Spicules are made up of calcium carbonate or silica.
(vii) These organisms feed upon small organisms taken in their body along with water. Water is taken in through ostia and given out through oscula.
(viii) These animals reproduce asexually by budding or by sexual method. They also have a good ability of regeneration. e.g. Sycon, Euspongia, (Bath sponge), Hyalonema, Euplectella, etc.