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