Exit Questions List 4 characteristics of Aquatic Seaweeds. Draw and label all five parts of a seaweed. List one characteristic and one example of a green algae. List one characteristic and one example of brown algae List one characteristic and one example of a red algae.

Aquatic Multicellular Primary Producers More commonly known as seaweeds and plants.

Seaweeds The most familiar types of marine algae are most commonly known as seaweeds. More formal names include macrophytes or macroalgae.

Seaweeds All are multicellular and eukaryotic. The structures and reproductive methods are more complex and elaborate than photosynthetic unicellular organisms.

General Structure Do not have roots, stems, and leaves.

Thallus The complete body of the seaweed, no matter what shape it takes.

Blades The leaf-like, flattened portion of the thallus. Has large surface area so most photosynthesis occurs here. Have no veins. Upper and lower surfaces are identical.

Pneumatocysts Gas-filled bladders that keep the blades close to the sea surface – more photosynthesis can take place here.

Stipe The distinct stem- like structure that provides support. The blades originate from here.

Holdfast A root-like structure that attaches the thallus to the bottom. Not involved in any significant absorption of water or nutrients. Does not penetrate sand or mud.

Characteristics Seaweeds do not generally have tissues that can be used for transporting water or nutrients. Instead they use Diffusion and Osmosis All of the organism is found in water and can photosynthesize, so transporting these materials isn’t necessary.

Main Types of Seaweeds Three main types of seaweeds: Green, brown, and red algae Best identified by chemical analysis because their natural color doesn’t always match their name.

Green Algae Most is found in freshwater and on land. Only about 700 (10% of the total species) are marine and most of these are unicellular.

Green Algae Most have a very simple thallus. Pigments are similar to land plants. Chlorophyll is not normally masked by other pigments so green algae are most often bright green.

Green Algae Sea lettuce – found in all temperatures of water Valonia – found in tropics and subtropics. Dead man’s fingers (Codium) – found in tropical to temperate waters (North America).

Brown Algae Colors can vary from olive green to dark brown. Yellow-brown pigments (particularly fucoxanthin) which masks the green chlorophyll.

Brown Alage Almost all species are marine. Are often the dominant primary producers on temperate and polar rocky coasts.

Brown Algae Include the Kelps: the most complex and largest of all brown algae. Some kelp can be as long as 100 m and grow 50 cm in one day.

Red Algae Very large group of organisms (more species than green and brown algae combined). Most are marine.

Red Alage Have red pigments called phycobilins. Live in most shallow water environments.

Red Algae Some are parasites of other algae while others are heterotrophs and not able to photosynthesize

Red Algae Gigantina – the most massive of the red algae. Blades up to 2 m. Coralline algae deposit calcium carbonate within the cell walls – aids in the formation of coral reefs.

Uses of Seaweeds Food: Many cultures eat seaweeds in a variety of ways. Most commonly we observe them in sushi. Mariculture: the farming of seaweed.

Uses of Seaweeds Seaweeds produce chemicals that help form gels and are often added to dairy products to keep them smooth (yogurt, ice cream, cheese, etc). They are also used to keep frostings and pies from drying out.

Uses of Seaweeds Shampoos, plastics, and pesticides. Cosmetics and laxatives. Hospitals can use seaweeds in some wound dressings.

Marine Flowering Plants There are many terrestrial flowering plants, but only a few marine flowering plants. These do have true roots, stems and leaves. They need specialized tissues to transport water, nutrients, and food.

Seagrasses The only true marine flowering plants. Most are found in shallow, well protected water in many temperate and tropical regions.

Seagrasses Most have flat, ribbon-like leaves. There are many organisms that live among the seagrasses including herbivores (seaturtles, manatees, and some fish).

Salt-marsh Plants They cannot be totally submerged by salt water. Not true marine flowering plants. They are plants that are tolerant of salty conditions. They cannot be totally submerged by salt water.

Salt-Marsh Plants They can survive in area that are partially submerged at high tide. Their leaves remain exposed to air and are able to excrete excess salt.

Mangroves Trees and shrubs adapted to live along tropical and subtropical shores. Land plants that can tolerate salt and are protected from waves.

Mangroves Leaves are usually thick to help reduce water loss. Some seeds will germinate while attached to the parent to give them a better chance at survival when they fall off.