Slide 1: The Algae ALGAE : ALGAE Algae belong to the Kingdom Protista
Algae are eukaryotes (cells have organelles)
Algae are mostly photosynthetic, like plants:
Have photosynthetic pigments
Many accessory pigments – blue, red, brown, gold
Require moist environments because they lack a waxy cuticle (remember: cuticle prevents water loss in terrestrial plants) General features of Algae : General features of Algae Can be microscopic or macroscopic: size ranges from bacteria size to 50 meters long!
Lack vascular (conducting) tissues – No xylem or phloem
No true roots, stems or leaves
Modes of sexual reproduction: Both sexual and asexual Diversity of Algae : Diversity of Algae There are millions of algal species, but we’ll focus in these five groups:
Kelps or Brown Algae
Green algae Diatoms : Diatoms Diatoms: Phylum - Bacillariophyta
Large group of algae (many unidentified). Relatively recently evolved group
Habitat: Diatoms live in cool oceans
Structure: mostly unicellular, have silica in their cell walls Diatoms : Diatoms Very important for aquatic food chains: they provide phytoplankton
Phytoplankton Zooplankton small fish larger fish mollusks whales
Can reproduce asexually for many generations, then sexually Dinoflagellates : Dinoflagellates Phylum - Dinoflagellata
Structure- Small, unicellular
Red tide a problem General Structure : General Structure Macro algae Slide 11: Seaweeds or Macroalgae are the large primary producers of the sea.
Though more complex than the unicellular algae, seaweeds still lack the complex structures found in land plants. Slide 12: This is a very diverse group, and although they lack true leaves, stems, and roots, they have a few common structures. Slide 13: The complete body is called the thallus no matter the growth form.
Usually, all regions of the thallus can photosynthesize. Slide 14: The leaf-like flattened portions are called blades.
The blades are usually the main photosynthetic region.These are not true leaves because they lack veins. Slide 15: Most seaweeds have gas-filled bladders or floats that will help them maximize sunlight exposure. Sometime these floats contain carbon monoxide. Slide 16: Some seaweeds have a stem-like structure called the stipe. This structure is not found on all seaweeds. Slide 17: The stipe provides support and can be long and tough, as in the Giant Kelp.
The stipe also allows a place for the attachment of the blades. Slide 18: A holdfast is a root-like structure that holds the seaweed to the bottom. This structure does not aid in gathering nutrients. Slide 19: The holdfast does not penetrate through sand or mud, so like this Sea Palm, most macroalgae are only found on hard sediments. Types ofMacroalgae : Types ofMacroalgae The are three types of macroalgae : The are three types of macroalgae Green Brown and Red Green Algae : Green Algae Phylum :Chlorophyta
About 700 of the 7,000 species of green algae are marine.
Of those, few are multicellular. Green Algae : Green Algae Green algae can be very common where the salinities vary a lot.( Bays, Estuaries, Tide Pools) Green Algae : Green Algae They are usually bright green because the chlorophyll is not masked by other pigments. Green Algae : Green Algae Green algae have a simple thallus when compared to red and brown algae. Green Algae : Green Algae Many forms are filamentous or form paper-thin sheets. Green Algae : Green Algae Others form spongy fingers as in this example of Dead Man’s Fingers. Slide 28: Phylum Chlorophyta – Green Algae Slide 29: Halimeda …a calcareous reef building alga Green Algae Slide 30: Chaetomorpha Bryopsis Slide 31: Enteromorpha Ulva Green Algae Brown Algae : Brown Algae Phylum : Phaeophyta
Almost all species of brown algae are marine.
The best know and the most complex are the kelps. Brown Algae : Brown Algae Color varies from olive green to dark brown because there are fucoxanthin yellow-brown pigments that mask the color of chlorophyll. Brown Algae : Brown Algae Besides the well known kelps, Sargasso weed is also a well known brown algae. Brown Algae : Brown Algae Sargasso weed often forms into large mats in the mid Atlantic where unique animals and communities can be found. Brown Algae : Brown Algae Notice anything here?
Can you see the Sargassum Angler Fish? Slide 37: Phylum Phaeophyta – Brown Algae Slide 38: Brown Algae Leathesia Scytosiphon Slide 39: Laminaria Egregia Brown Algae Slide 40: Postelsia Brown Algae Slide 41: Macrocystis -- Kelp Brown Algae RED ALGAE : RED ALGAE Phylum : Rhodophyta
Red algae but colors vary
Smaller than brown algae and live in deeper waters
Phycobilins – pigment for absorbing light
Some coated with polysaccharide carageenan – cosmetics, gel capsules, cheeses
Agar – extracted from cell walls of red algae Red Algae : Red Algae There are more species of marine red algae than green or brown.
Most are actually red! Red Algae : Red Algae Some red algae have calcium carbonate within their cell walls.
These, help form coral reefs. Slide 45: Class Rhodophyta – Red Algae Slide 46: Calliarthron Melobesia Red Algae Slide 47: Corallina Palmaria Red Algae REPRODUCTION : REPRODUCTION MOST REPRODUCE BOTH SEXUALLY AND ASEXUALLY
Most sexual reproduction is triggered by environmental stress
Plus and minus gametes Slide 49: The life cycles of many algae include both a diploid and a haploid generation.
Reproduction in Chlamydomonas
The unicellular Chlamydomonas spends most of its life in the haploid stage. Reproduction in Green Algae : Copyright Pearson Prentice Hall Reproduction in Green Algae Asexual Reproduction in Chlamydomonas zoospores In suitable living conditions, this haploid cell reproduces asexually, producing cells called zoospores by mitosis. Reproduction in Green Algae : Copyright Pearson Prentice Hall Reproduction in Green Algae If conditions become unfavorable, Chlamydomonas can also reproduce sexually. Reproduction in Green Algae : Copyright Pearson Prentice Hall Reproduction in Green Algae Sexual Reproduction in Chlamydomonas Release of haploid cells Reproduction in Green Algae : Copyright Pearson Prentice Hall Reproduction in Green Algae Haploid cells undergo mitosis, but release gametes instead of zoospores.
The zoospores are of two opposite mating types—plus (+) and minus (-). Pairing of plus and minus gametes Reproduction in Green Algae : Copyright Pearson Prentice Hall Reproduction in Green Algae The plus and minus gametes form pairs and fuse, forming a diploid zygote. Reproduction in Green Algae : Copyright Pearson Prentice Hall Reproduction in Green Algae The zygote grows a thick protective wall. Within this protective wall, Chlamydomonas can survive conditions that otherwise would kill it. Reproduction in Green Algae : Copyright Pearson Prentice Hall Reproduction in Green Algae When conditions again become favorable, the zygote grows, divides by meiosis, and produces four haploid cells. Reproduction in Green Algae : Copyright Pearson Prentice Hall Reproduction in Green Algae Reproduction in Chlamydomonas zoospores Mature cell Pairing of plus andminus gametes Zygote Release of haploid cells Commercial uses of algae : Commercial uses of algae Algin – a thickening agent for food processing (brown algae)
Carrageenan – foods, puddings, ice cream, toothpaste (red algae)
Iodine (brown algae)
Agar – for growth media used in research (red algae)
As food – red and brown algae
As plant fertilizers
Diatomaceous earth: used for filtering water, insulating, soundproofing