Ectocarpus
Asad Razzaq
Habitat
• It is a marine brown alga, distributed throughout the temperate and tropical seas of the world.
Habitat
• Plant body is:
• filamentous, much branched and heterotrichous,
• having prostrate system and
• well-developed branched erect system.
Habit
• The prostrate system is profusely branched
and attached with the substratum.
• Some species develop multicellular hairs
from the prostrate system.
• The prostrate system serves the function of
anchorage with the substratum or on other
plants
• Erect system is photosynthetic and bears
reproductive organs.
Plant body
• The apical part of each filament
generally terminates into hairs.
• Two types of plant bodies are
differentiated genetically, one is
haploid and other one is diploid.
• Both haploid and diploid plants are
morphogically identical.
Cell Structure
• The cells are rectangular or cylindrical.
• Cell wall is differentiated into outer pectic
and inner cellulosic layers.
• The characteristic gelatinous substance
present in the cell wall is composed of
algin and fucoiden.
• Inner to the wall, cell membrane is present
which encircles the protoplast.
Cell Structure
• The protoplast contains one central
nucleus, many chromatophores and
many vacuoles called physodes.
• Morphologically, haploid and diploid
vegetative filaments are almost alike,
but the cells of haploid filaments are
comparatively shorter in length than
the diploid filaments.
Cell Structure
• The number and shape of
chromatophore varies with species.
• They may be ribbon-shaped, band-
shaped, discoid etc. and are associated
with pyrenoids.
• The photosynthetic pigments are
chlorophyll a, chlorophyll c, β-carotene
and fucoxanthin.
• The fucoxanthin masks the chlorophyll
and gives the characteristic brown
coloration.
Asexual Reproduction
• It takes place by biflagellate zoospores.
• One whiplash and other tinsel-type of
flagellum.
• The diploid plant (2n) develops two types
of sporangia.
• Unilocular sporangia &
plurilocular/neutral sporangia.
Unilocular sporangia
• The unilocular sporangia develop haploid
zoospores (zoomeiospores)
Plurilocular sporangia
• Plurilocular sporangia develop diploid zoospores.
Sexual Reproduction
• Isogamous and anisogamous type.
• Anisogamy is very common.
• Morphological anisogamy and
physiological anisogamy.
• The gametes are produced inside the
plurilocular gametangia, developed
on haploid plants.
Plurilocular Gametangia
• large, elongated, sessile or short stalked,
multicellular structures.
• Morphologically similar to plurilocular
sporangia
• It produces haploid gametes; While
plurilocular sporangia produce diploid
zoospores.
• The gametes are slightly smaller in size than
the zoospores.
• The development of both is similar
• Liberation of gametes resembles zoospore
liberation from the plurilocular sporangia
Fertilisation
• Physiological anisogamy = uniting gametes are morphologically similar
• Morphological anisogamy = female gamete is larger than the male gametes.
• During fertilization, many male gametes encircle the female gamete and get
entangled by the anterior large flagellum.
• This stage is called clump formation
• Out of many, only one male gamete fuses with the female gamete and the
remaining gametes go astray and gradually get destroyed.
• The uniting gametes then form zygote through plasmogamy and karyogamy.
Germination of Zygote
• The zygote undergoes germination without
any reduction division and rest.
• On germination it develops into a
sporophytic (2n) plant.
• The sporophytic plant again develops
unilocular and plurilocular sporangia.
Algae and habitat
•r
Algae and habitat
•c
