LAB ( 9 )
Division :Rhodophyta
 Red algae are red because of the presence of the pigment
phycoerythrin & phycocyanin ; this pigment reflects red light and
absorbs blue light. Because blue light penetrates water to a greater
depth than light of longer wavelengths, these pigments allow red
algae to photosynthesize and live at somewhat greater depths
than most other "algae". Some rhodophytes have very little
phycoerythrin, and may appear green or bluish from the
chlorophyll and other pigments present in them.
 food reserves as floridean polysaccharides .

with phycobiliproteins as accessory pigments (giving them their
red color) .

Most red algae are also multicellular, macroscopic, marine .

have sexual reproduction. They often have alternation of
generations and may have three generations rather than two .
 They are used to make products such as agar .
Division : Rhodophyta
Class : Rhodophyceae
Order : Ceramiales
Family : Rhodomelaceae
Genus : Polysiphonia

It is entirely marine, found growing on rock, other algae .
 It is filamentous and usually well branched some plants reaching a
length of about 30 cm .
 Their colour is due to the red pigment phycobilin, masking the
green colour of chlorophyll, This red pigment is very well suited to
absorb the green and blue-green light in somewhat deeper sea
water .
 They are attached by rhizoids or haptera to a rocky surface or
other alga.
 Fragments of the plants, after surviving a winter or buried under
sand can grow again into healthy plants if circumstances become
better .
 The life-cycle of the red algae has three stages (triphasic) it consists
of a sequence of a gametangial, carposporangial and
tetrasporangial phases . Male (haploid) plants (the male
gametophytes) produce spermatia and the female plants (the
female gametophytes) produce the carpogonium , After
fertilization the diploid nucleus migrates and fuses with an
auxiliary cell , the diploid zygote develops to become the
carposporophyte , The diploid carpospores produced in the
carposporangium, they grow to form filamentous diploid plants
similar to the gametophyte , This diploid plant is the
tetrasporophyte when adult produced spores in fours after meiosis
These spores grow to become the male and female plants thus
completing the cycle .
Tetrasporophytes of Polysiphonia
carposporophytes of Polysiphonia
gametophytes of Polysiphonia