Phyla Porifera
Sponges cells are specialized so the cells carryout different functions. Unlike most other animals similar cells are not group together to make tissues or organs. They have the simplest cellular organization found among parazoans. Sponges also have pores called ostia and canals for water to pass through. Beating flagella helps drive the movement of water. These flagella are located on cells called choanocytes. Sponges have either radial symmetry or are asymetrical. sponges have 3 different types of body plans; asconoid, syconoid, and leuconoid.
asconoid:
syconoid:
leuconoid:
Sponges can reproduce sexually and asexually. When they reproduce asexually external budding is being used. Some species even use internal budding. These buds are called gemmules. The gemmules are very strong, in that they can survive some conditions so harsh even the sponge itself won't be able to survive. Sexual reproduction in the mesohyl of the sponge. The male sponge will release gametes into the water surrounding it so it's surrounding sponges are able to take it in the same way they take in food. The spermatozoa cells are retrieved by collar cells. The collar cells then loose their collars and transform into ameoba like cells, specialized to carry the sperm to the eggs. Next the fertilized egg develops into a bastula and is then released into the water. In some cases the larva will settle and turn into an adult sponge or they may float around and be planktonic for a while.
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