ALGAE
CHLOROPHYCEAE
They are largely aquatic (both fresh water as well as marine )they occur in other habitats also like moist stones, soils, wood They are also in associations #with fungi = lichen and with animals #with sloth
PHEOPHYCEAE
RHODOPHYCEAE
FORM AND SIZE IS HIGHLY VARIABLE
FROM UNICELLULAR MICROSCOPIC FORMS = CHLAMYDOMONAS
FILAMENTOUS =SPIROGYRA $ ULOTHRIX
COLONIAL = VOLVOX
MASSIVE PLANT BODIES FORM SUCH AS KELPS
REPRODUCTION
VEGETATIVE i.e BY FRAGMENTATION each fragment on germination develops into a thallus
ASEXUAL BY PRODUCTION OF DIFFERENT TYPES OF SPORES -most common are the zoospores that are biflagellated pear shaped and on germination give rise to new plants
SEXUAL BY ISOGAMY ,ANISOGAMY ,OOGAMY- OOGAMY BY VOLVOX AND FUCUS
USES
half of the CO2 fixation in the atmosphere is done by algae by the process of photosynthesis
they increase the amount of dissolved o2 in the immediate environment
they are the primary producers of energy rich compounds which form the basis of food cycles of all aquatic animals
many species of PORPHYRA , LAMINARIA AND SARGASSUM are among the 70 species used as food
certain marine red and brown algae produce large amounts of hydrocolloids red algae - carrageen and brown algae - algin
AGAR is produced from gelidium and gracilaria
CHLORELLA is protein rich and is consumed by space travellers
green algae
plant body may be unicellular colonial or filamentous
pigments
chlorophyll a,b
localized in definite chloroplasts
chloroplasts are discoid ,plate like ,reticulate cup-shaped ,spiral ,ribbon shaped
most of them have more than one storage bodies called pyrenoids located in the chloroplasts pyrenoids contain proteins besides starch some algae may store food in the form of oil droplets
green algae usually have a rigid cell wall made of inner layer of cellulose and an outer layer of pectose
REPRODUCTION
VEGETATIVE by fragmentation or by formation of different types of spores
ASEXUAL by flagellated zoospores in zoosporangium
sexual reproduction may show variation in the type and formation of sex cells and it may be isogamous ,anisogamous ,oogamous
CHLOROPHYLL
chlorophyll A -primary photosynthetic pigment
chlorophyll C- found in certain marine algae
chlorophyll B-accesory pigment that collects energy and passes it on to chlorophyll A
OTH PIGMENTS
CAROTENOIDS -yellow/orange/red
XANTHOPLHYLL ,eg fucoxanthin - yellow
SEAWEED - COMMON NAME FOR SPECIES OF MARINE ALGAE AND PLANTS THAT GROW IN THE OCEAN AS WELL AS IN RIVERS, LAKES AND OTHER WATER BODIES
EDIBLE GREEN ALGAE MOST ARE TOXIC
MOST EDIBLE SEAWEEDS ARE MARINE ALGAE WHEREAS MOST FRESHWATER ALGAE ARE TOXIC
CHLORELLA
ULVA -GUTWEED
CAULERPA - SEA GRAPES
SEA LETTUCE - A GENUS OF ULVA (FREE FLOATING AND ATTACHED )