Vary in size: microscopic (unicellular) to macroscopic
Important primary producers in marine environments
Thallus: simple body structure of algae
Typically has three parts
Holdfast: root-like, anchors algae to substrate
Stipe: stem-like; hold up blades, absorbs shock of waves,
Blades: leaf-like; site of sexual reproduction
(pneumatocyst): gas filled floats used in flotation
Also known as Green Algae
Can be unicellular or multicellular
Live in terrestrial, freshwater and marine environments
Contain chlorophyll a and b as the main pigment
It is believed that plants evolved from green algae.
Calcareous algae play an important role in the formation of coral reefs.
Also known as Brown Algae
Vary from olive green to dark brown
Contains the pigment Fucoxanthin (yellow-brown) in addition to chlorophyll a and c
Contains the algae known as Kelp
Most complex and largest of all brown algae
Areas with high density of kelp are called kelp forests or kelp beds.
Most are found in cold, nutrient rich, shallow waters
Mainly found on coastlines where upwellings occur.
Found in warm water
Small, spherical air bladders to keep seaweed floating at the surface.
Many organisms live in sargassum and are found no where else.
Provides food and shelter for baby sea turtles.
Sargasso Sea: North Atlantic
Also known as Red Algae
More species than green and brown algae combined
Contain pigments known as phycobilins (phycocyanin and phycoerythrin) and chlorophyll a
Coraline algae are important in coral reef formation
Leafy part of the algae is the thallus
The diploid sporophyte thallus produces spores
Spores have flagella and swim away, once they reach a suitable substrate they develop into a haploid gametophyte thallus.
The gametophyte thallus produces gametes
(sperm and egg cells)
Two gametes fuse to produce a zygote and develop into the next leafy diploid sporophyte
Reproductive cycle with the succession of two types of generations: sporophyte generation-asexual and gametophyte generation- sexual
Found in some land plants as well.
Phycocolloids: gelatinous chemicals used in food processing
-algin: stabilizer and emulsifier in dairy, processed foods, shampoo, shaving cream, plastics, pesticides, etc….
-carrageenan: emulsifier; gives body to dairy and processed foods
-agar: form jellies
Flowering Plants: A.K.A. Angiosperms
Dominate the land only a few in the ocean.
Only seagrasses are truly marine
Not grasses but members of the lily family
Completely submerged, found in shallow subtidal zones
Create hiding places for other organisms
Underground stems (rhizomes) help stabilize sandy ocean floor
Flower underwater and disperse pollen in thread under water
Grow along the sandy beaches, never completely submerged by water
Halophytes: contain salt glands which help them excrete excess salt.
Provide habitat for crabs and mussels
Help break down industrial pollutants that flow into marshes
Trees and shrubs adapted to live along tropical and subtropical shores
Offer protection for young organisms
Over 80 different species
Coping with salt:
filtering out as much as 90 percent of the salt found in seawater as it enters their roots.
Some species excrete salt through glands in their leaves.
concentrate salt in older leaves or bark, when the leaves drop or the bark sheds, the stored salt goes with them.
Hoard fresh water:
Like desert plants, mangroves store fresh water in thick succulent leaves.
A waxy coating on the leaves of some mangrove species seals in water and minimizes evaporation.
Small hairs on the leaves of other species deflect wind and sunlight, which reduces water loss through the tiny openings where gases enter and exit during photosynthesis..
Breathe in a variety of ways:
Some mangroves grow pencil-like roots that stick up out of the dense, wet ground like snorkels. These breathing tubes, called pneumatophores, allow mangroves to cope with daily flooding by the tides.
Pneumatophores take in oxygen from the air unless they're clogged or submerged for too long.