chrysophyta

Division : Chrysophyta ((( golden algae )))
they are particularly important in lakes, where they may be the primary source of food for zooplankton , They are not considered truly autotrophic because all chrysophytes become facultatively heterotrophic in the absence of adequate light may be feeding on bacteria .
This division have 3 classes :
Class 1 : Xanthophyceae ((( yellow – green algea )))
1- Habitat : Most live in freshwater, marine and damp soil .
2- Growth form : vary from single-celled flagellates to simple colonial and filamentous forms , siphonaceous .
3-chloroplasts contain the photosynthetic pigments Chlorophyll a, Chlorophyll c (This gives them a characteristic yellowish-green color) , ?-Carotene, vaucheriaxanthin .
4-food reserves : as polysaccharide ((chrysolaminarin)) out of chloroplast .
5-it have typically 2 unequal flagella the larger usually flimmer .

Division : Chrysophyta
Class 1 : Xanthophyceae
Order : Vaucheriales
Family : Vaucheriaceae
Genus : Vaucheria .

• It composed of many tubular filaments which can be very long. The plant is coenocytic and shares it s nuclei and chloroplasts , with a large central vacuole pushing against the surrounding cytoplasm , The chloroplasts are located on the periphery of the cytoplasm with the nuclei aggregating toward the center near the vacuole .
• Types of reproduction 1- asexual :- by large solitary zoospore. It formed when the apex of filament swells up, becomes club shaped and is separated from rest of filament by a septum. This club shaped body is called zoosporangium.
2- Sexual reproduction by oogamy .
3-vegetative reproduction by Fragmentation .