c hapter 6 seaweeds and plants. s eaweeds not plants! multicellular algae no roots, stems, leaves...
TRANSCRIPT
CHAPTER 6Seaweeds and Plants
SEAWEEDS
NOT PLANTS!Multicellular algaeNo roots, stems, leavesPrimary producers Important for Habitat
More accurately, MACROPHYTES or MACROALGAE
SEAWEED STRUCTURE
Thallus – the entire body Blades – flattened, leaf-like
portion; large area for photosynthesis (NOT leaves)
Pneumatocysts (floats) – gas-filled bladders (usually carbon monoxide) that keep blades close to surface
Stipe – stem-like structure used for support; not used for transport of water or nutrients
Holdfast – attaches the thallus to the bottom (not used in transport)
TYPES OF SEAWEEDS
TYPES OF SEAWEEDS
Classified based upon their pigments Revealed upon chemical analysis Green (phylum Chlorophyta) Brown (phylum Heterokontophyta; Class Phaeophyta) Red (phylum Rhodophyta)
GREEN ALGAE - CHLOROPHYTA
Only 10% of species (around 700) are marine Most marine species are unicelluar More dominant in estuarine and tide pool
areas Tolerate salinity variation
Land plants believed to have evolved from them
Examples: Enteromorpha Ulva Caulerpa Codium Halimeda
ENTEROMORPHA
Filamentous Thallus is tube shaped. Common in bays, estuaries, exposed
coastlines. Re-colonizers that can tolerate polluted areas
Photo: Enteromorpha prolifera – Elkhorm Slough, CA by Judith Connor
Photo: Enteromorpha intertinalis -- Stillwater Cove, Pebble Beach CA
ULVA
Sea lettuce Not a distinct genera from Enteromorpha Forms sheets but only in the presence of
bacteria or other algal species Widespread, first-colonizers on new substrate
© 2006 Jan Holmes
CAULERPA
Composed of multiple think tubes (siphons) Multinucleated Proliferative, especially in marine aquariums Tropical/subtropical
Caulerpa sp. Caulerpa racemosa
CODIUM
“Multinucleated filaments woven into a spongy, branching thallus”
Eaten by sea slugs Chloroplasts of the algae can remain alive inside
these animals
HALIMEDA
Calcareous green alga Play an important role in the build up of
tropical reefs.
BROWN ALGAE - PHAEOPHYTA Almost all 1,500 species are marine Can dominate temperate and polar rocky coasts Vary in complexity (few celled to kelps) Color varies: olive green to dark brown
Due to presence of yellow-brown pigment, fucoxanthin
Examples: Ectocarpus Dictyota Fucus Sargassum Laminaria Nereocystis Macrocystis
ECTOCARPUS
branching, filamentous May exist attached to substrate or free-
floating widespread
DICTYOTA
Fan-shaped Lightly calcified Now widespread, but originally from
Northeast North America and Mediterranean.
FUCUS
Known as a ‘rockweed’ or ‘wracks’ along coastlines Have gas-filled floats (pneumatocysts) Leathery thalli often covered with mucus to
withstand prolonged air exposure Strong disk-shaped holdfasts to endure intertidal
zone
SARGASSUM
Have many gas-filled bladders Can grow on rocks or in huge floating masses Common in the Gulf of Mexico & Sargasso Sea Important for nursery and transport
communities
LAMINARIA
Sea palms, feather boa kelps, etc. Up to 3m in length Single or small group of large blades attached to
a single stipe. Important food source
NEREOCYSTIS
Bull kelps Whip-like stipe that is up to 30m long Large spherical pneumatocyst at one end
MACROCYSTIS
Giant kelps Enormous holdfasts that anchor multiple stipes Elongate blades branch from stipes, each with
a gas-filled (CO) pneumatocyst Grow up to 100m (up to 20 cm/day) Form dense forests or ‘kelp beds’
Among most productive marine ecosystems Are harvested for several natural products
RED ALGAE - RHODOPHYTA
Most numerous (~4,000 species) in marine environment
Contain a red pigment (phycobilins) Harvested for food and other natural products Most are filamentous Some are heterotrophic and parasitic on other
algae Examples:
Ceramium Chondrus Nemalion Porphyra Corallina
CERAMIUM
Small, filamentous algae Epiphytic Produce chemicals that make them
distasteful
CHONDRUS
Irish moss Ranges across the North Atlantic Shape varies with changes in temperature,
salinity, and light availability
NEMALION
Grows as a branched ‘worm’ on rocks in the intertidal zone.
Softly cartilaginous
PORPHYRA
Common on rocky shores Polar to tropical distribution
CORALLINA
Coralline algae Deposit calcium carbonate within their cell
walls Can be an important reef building species in
tropical waters Can grow branching or encrusting
LIFE HISTORY
Refers to the series of growth, metamorphoses, and reproductive stages in an organism’s generation.
A little review: Sexual vs. asexual reproduction Diploid vs. haploid Gametes Mitosis vs. Meiosis What’s a spore?
ALGAL GENERATIONS
Sporophyte – diploid (2n) , spore producing generation
Gametophyte – haploid (n), gamete producing generation
Alternation of generations – life histories in which two generations, a sporophyte and a gametophyte, exist
Can take four basic patterns
LIFE HISTORIES OF VARIOUS SEAWEEDS
HALIMEDA LIFE HISTORY
Economic Importance of Seaweeds
Harvested for food (mariculture) Produce phycocolloids
used in food processing & manufacturing as thickeners or gels
Algin
produced from giant kelp (Macrocystis) and bull kelp (Laminaria) Stabilizer and emulsifier in dairy products Prevents drying of frostings and toppings Pharmaceuticals Shampoo Plastics Pesticides Used in textiles as a thickener for printing paste
SPHERICAL MANGO RAVIOLI
Blend the Citras with 250g of water, add the Algin and blend once more.
Bring to a boil, allow to cool and mix with the mango puree. Blend 1000g of water with Calcic. Pour the contents of a dosing spoon full of the mango and Algin mixture into this Calcic bath, leave for 2 minutes and wash in cold water. Repeat until all of the ravioli are made.
Carageenan
Produced from red algae such as Chondrus Used as an emulsifier especially in dairy
products, soy milk, processed foods, and puddings
Toothpastes and other beauty products Used in vaccines against HPV and other sexually
transmitted Link
Ingredients: skim milk, partially hydrogenated soybean oil, disodium phosphate,
carrageenan, Vitamin A Palmitate, and Vitamin D3
Agar
Extracted from several red algae including (Gelidium, Gelidiella, and Pterocladiella)
Uses: protect meats during canning low-calorie (diet) foods thickener laxatives, cosmetics, and pharmaceuticals as a medium for bacteria and mold growth
Sugar Coated Pills: Each sugar coated pill contains: sennosides USP 15 mg. Nonmedicinal
ingredients: acacia, alginic acid, calcium phosphate, carnauba wax, cellulose, iron
oxide, magnesium stearate, sodium benzoate, sodium lauryl sulfate, starch, stearic acid, sucrose, talc and titanium dioxide. Blister packs, boxes of 10, 30 and 60.
FLOWERING PLANTS
Have true leaves, stems, and roots Structures to transport water, nutrients, and food
Reproduce sexually with the production of spores in flowers
Three types of marine plants; Seagrasses – completely submerged in seawater Salt-marsh plants – roots only covered at high tide Mangroves – trees and shrubs that live along shores,
roots adapted to salt