The Nostocaceae are a family of cyanobacteria that forms filament-shaped colonies enclosed in mucus or a gelatinous sheath. Some genera in this family are found primarily in fresh water (such as Nostoc), while others are found primarily in salt water (such as Nodularia). Other genera (e.g. Anabaena) may be found in both fresh and salt water. Like other cyanobacteria, these bacteria sometimes contain photosynthetic pigments in their cytoplasm to perform photosynthesis. The particular pigments they contain gives the cells a bluish-green color.