Sponges (Phylum: Porifera) are asymmetric, multi-celled animals. They are sessile and aquatic, and lack nervous, digestive or circulatory systems. [1] There is evidence in the literature to suggest that animals may have evolved a nervous system twice. [2] {{Animalia}}

Sponge

Taxonomic classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Porifera*
Grant in Todd, 1836
Included groups

Calcarea
Hexactinellida
Demospongiae

Excluded groups

Crown radiata

References edit