Transcript Multi-cellular Primary Producers_6

Multi-cellular Primary Producers:
Seaweeds and Plants
• Multi-cellular algae are commonly referred to
as seaweeds
• Seaweeds belong to Kingdom Protista, and are
further classified into divisions (or phylum)
according to their characteristic color
(pigmentation)
• Like unicellular algae, all multi-cellular algae
are eukaryotic
Three Domains of Life
Kingdom Protista
Multi-cellular Algae: Seaweeds
• Seaweeds are more formally referred to by
biologists as macrophytes or macroalgae
• Seaweeds are not plants and so lack true
leaves, stems, and roots
• The complete body is known as
the thallus whether it is a
filament, a thin leafy sheet, or
a giant kelp
General Structure
• All portions of the thallus are capable of
photosynthesis
• The leaf-like, flattened portions of the thallus
are known as blades
– large surface area; main photosynthetic region
• Gas-filled bladders known as pneumatocysts
help keep the blade close to the sea surface
• Some seaweeds have a distinctive, stem-like
structure, the stipe, which provides support
Plant
Algae
http://atlasveg.ib.usp.br/English/focara.html
General Structure
• A structure resembling roots, the holdfast,
attaches the thallus to the bottom
– NOT involved in any significant absorption of
water and nutrients
– Does not penetrate through sand and mud as true
plant roots do
• Restricts seaweeds to hard bottoms; not found
in sandy, soft bottom habitats
• Water and nutrients are transferred directly
across the surface of the thallus
Types of Seaweeds
• There are three types of seaweeds
– The green algae
– The brown algae
– The red algae
Green Algae: Phylum Chlorophyta
• Green algae belong to phylum (or “division”)
Chlorophyta
• Most green algae live in freshwater and
terrestrial environments; only ~10% of the
estimated 7,000 species are marine
• Nonetheless, many species of green algae
dominate bays and estuaries and isolated tidal
pools on rocky coasts
Green Algae: Phylum Chlorophyta
• Chlorophyll in both green algae and plants are
not normally masked by other pigments
• Land plants are believed to have evolved from
green algae; considered by many taxonomists
as belonging to Kingdom Plantae!
Common Long Island Chlorophytes
Codium fragile
(“Dead Man’s
Fingers”)
Ulva lactuca
(“Sea lettuce”)
http://www.ubcbotanicalgarden.org/potd/2007/10/codium_fragile_subsp_tomentosoides_1.php
Enteromorpha sp.
(“Gutweed”)
http://www.biopix.dk/Photo.asp?Language=la&PhotoId=11271
Brown Algae: Phylum Phaeophyta
• Brown algae belong to phylum (or “division”)
Phaeophyta
• Color varies from olive green to dark brown,
but are classified by having a preponderance
of yellow-brown photosynthetic pigments,
particularly fucoxanthin
• Nearly all 1,500 species are marine
• Include the largest and most complex
seaweeds
Brown Algae: Phylum Phaeophyta
• Many species have gas-filled floats
(pneumatocysts); e.g., rockweeds or wracks,
Sargassum weed
http://www.physorg.com/news100350969.html
Brown Algae: Phylum Phaeophyta
• The kelps are the most complex and largest of all
brown algae
– Consist of a single, or numerous large blade(s)
– The stipes of giant kelp, Macrocystis can reach
lengths of 100 m and
grow ~1 ft per day!
– Provides food and
shelter for many other
marine organisms
http://www.rmrs.nau.edu/usamab/general%20description%20channel%20islands.htm
KELP!!!
Kelp community with
sea otters
http://www.otterproject.org/atf/cf/%7B1032ABCB-19F9-4CB6-8364-2F74F73B3013%7D/Otter_image4.jpg
Kelp community without sea otters
http://blackcormorant.blogs.com/photos/uncategorized/kelpurchins_415_030.jpg
http://sbc.lternet.edu/sites/biome_kelpforest.html
Red Algae: Phylum Rhodophyta
• Red algae belong to phylum (or “division”)
Rhodophyta
• There are more species of marine red algae
than green and brown algae combined!
• The chlorophyll of red algae is masked by large
amounts of red pigments called phycobilins
• Nearly all 4,000 species are marine
• Dominate in tropical and subtropical regions
Common Long Island Rhodophytes
Chondrus crispus
(“Irish moss”)
Palmaria palmata
(“Dulce”)
Porphyra sp.
(“Laver”)
Multi-cellular Primary Producers:
The Plants
• Worldwide, there are 5,000-6,000 species of
seaweed and only 55 species of seagrass!
• Seagrasses are flowering plants belonging to
the kingdom Plantae
– Not actually a grass
– Related to lilies; evolved
from land plants!
– True leaves, stems, and
roots
Seagrasses
• Underground roots and rhizomes (horizontal
stems) extract nutrients from the sediment
and hold the plant in its place
• Seagrasses have cell walls made out of
cellulose (a characteristic of all plants) which
provide support for the plant and keep the
plant vertical in the
water column
Seagrasses
• Seagrass provides important shelter and food
for many marine inhabitants
• Because of the protection they provide,
seagrass communities serve as important
nursery grounds for developing fish & shellfish
http://www.flickr.com/photos/19727876@N00/415368318/
Common seagrass of Long Island
Zostera marina
(“Eel grass”)
http://www.ceoe.udel.edu/cms/jgallagher/tigani/kt_index.html
How NOT to drive your boat through seagrass...
http://www.dep.state.fl.us/COASTAL/images/habitats/seagrasses/Aerial1.jpg