Pls explain internal fertilisation in sponges


The Phylum Porifera (sponges) reproduces sexually by the formation of gametes. The fertilization is internal and development is indirect having a larval stage that is morphologically distinct from the adult. Examples as in Spongilla and Euspongia. Gemmules are a means of asexual reproduction, common in sponges. They are called internal buds, as they are formed internally in a process similar to budding, i.e, by mitotic divisions. Gemmules are found in sponges which are formed due to asexual reproduction.
​​​​​The sperm cells are released into the water and then they enter a female sponge through a pore.

Sponges have characteristic cells known as choanocytes or collar cell that lines the inner portion of their body. These cells possess flagella that help them in producing water current and in reproduction. They are responsible for trapping the sperms present in water current from other sponges and bring it to the egg due to which fertilisation occurs.

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