Pengenalan Dunia Algae Suratman Jurusan Biologi FMIPA UNS Surakarta
Karakteristik algae
Alga (tunggal) atau algae (jamak) kadangkala disebut ganggang atau seaweeds. Ilmu yang mempelajari alga secara khusus disebut fikologi atau algologi Mengandung klorofil (hingga 4 macam klorofil) dan dapat melangsungkan fotosintesis. Kadang mengandung pyrenoid. Mereka dapat menghasilkan oxygen sebagai produk fotosintesis. Uniselluler dan multiselluler. Umumnya hidup di tempat yang cukup air..> Life cycle has motile stage (swimming)
Struktur Algae Algae berhabitus talus (Thallophyta) ..> akar, batang dan daun belum berkembang dengan sempurna. Pada alga makroskopis, kadang-kadang dapat dibedakan atas alat perlekatan (holdfast/rizoid), batang/tangkai (stipe) dan helai daun (blade), namun batang dan daun umumnya menyatu. Thallus juga dilengkapi dengan pelampung (bladder) untuk menjaga blade dekat permukaan air
Structure of Seaweeds A thallus can have many specialized structures including : 1. Frond or blade Flattened, there is no specific upper or lower side to the blade. Both sides are capable of capturing sunlight for photosynthesis 2. Holdfast The structure attaching the thallus to a surface. It is not a root structure, it does not go into the sedimen. It does not absorb nutrients 3. Stipe A stem-like region between the holdfast and blade of some seaweeds 4. Pneumatocysts (air bladder) A gas filled float to buoy up the blades near the sunlight
Primary parts of algae
thallus
Composition of cell walls • Primarily cellulose but some of them consist of pectin and alginates acid. Chlorophyta (cellulose and pectin); Phaeophyta (cellulose, pectin, alginates acid); Rhodophyta (only cellulose). • May be impregnated with calcium carbonate in calcareous algae • Many seaweeds secrete slimy mucilage (polymers of several sugars) as a cell. Covering : holds moisture and may prevent desiccation • Some have a protective cuticle ..> a multilayered protein covering
Seagrasses vs Seaweeds How are seagrasses different from seaweeds?
WHAT ARE SEAGRASSES? • Seagrasses are plants that have evolved to live in sea water. • They are called 'seagrass' because most have grassy leaves, but none is a true grass. • Have vascular bundles • Have flowers
CHARACTERISTICS OF SEAGRASSES • Well developed horizontal stems called rhizomes (occur below the substratum). • Small erect branches of the rhizome— short shoots. Leaves arise from these structures or directly from the rhizome. • Roots develop on the rhizome and on the lower parts of the short shoots. Serve as anchorage and uptake of nutrients. • Leaves-flat have aerenchyma (tissue with air spaces). Leaves have a thin cuticle that allows gas and nutrient diffusion from the surrounding water.
lacunae
WHY ARE SEAGRASSES IMPORTANT? • Habitats for many species. Attachment sites for many epiphytic algae and invertebrates. • Food sources for many animals (birds, turtles, etc). • Provide protection for young marine animals. • Maintain water clarity by trapping fine sediments and particles. • Dense growth of seagrass leaves creates calm conditions by reducing water movement by currents and waves.
COMMON SEAGRASSES
Manatee grass Syringodium filiforme
Turtle grass Thalassia testudinum
Eelgrass Zostera marina
FOSSIL HISTORY OF ALGAE • Dates back to 3.5 billion years before present. • First prokoratic unicelluler algae— Cyanobacteria—photosynthetic, without any complex organization. • Cells with complex organization evolved with nucleus and other cellular organelles. With the exception of the cyanobacteria, algae are eukaryotes—that is, the insides of their cells are organized into separate membrane-wrapped organelles, including a nucleus and mitochondria.
What is different in land plants? Green algae Charophytes
Evolution of number of anatomical, physiological and reproductive adaptations
Plants Land colonization
What do algae and land plants share in common? z Both undergo photosynthesis. Which means they both contain chlorophyll and they both can make their own food (autotrophic). z They have the same life cycle called alternation of generations. z Plants and green algae share similarities in cell division. z Plants and green algae has similar biochemical characteristics (same biosynthetic pigment; same cell wall component; same carbohydrates storage material)
Algae and plants have the same life cycle called alternation of generations.
How are algae different with higher plants? • Algae lack the roots, stems, leaves, and other structures typical of true plants. The photosynthetic portion of the alga is a thallus while the attachment portion comprises hair-like rhizoids (holdfast) ..> Thallophytes • Algae do not have vascular tissues..> non vascular plants. No “pipes” to carry fluids. An alga moves its materials strictly through diffusion and osmosis. • Algae do not form embryos within protective coverings. Mostly, sperm and eggs of algae fuse in the open water and the zygote develops into a new plant without any protection. For other plant groups the zygote develops into an embryo within the protection of the parent plant. For this reason, all other plant groups are termed Embryophytes.
How are algae different (continued)
Reproductive structures: The gametes are produced within a single cell. There is no jacket of sterile cells protecting the gametes
Variations in pigments. Variations in cell structure ..> unicellular, colonial and multicellular forms.
Compare plants to algae
What makes a land plant better adapted to live on land than Algae? Has ability to store and regulate water loss because of waxes and oils found on the plant called lipids. The leaves are able to carry out photosynthesis on land. In order to provide nutrients to those leaves plants must be able to transport water and nutrients to different parts of the plant. Plants must have roots to take in those water and nutrients from the ground. Reproductive strategies, like the ability to produce seeds, allow plants to live out of water.
CELLULAR ORGANIZATION OF ALGAE • Flagella=organs of locomotion. • Chloroplast=site of photosynthesis. Thylakoids are present in the chloroplast. The pigments are present in the thylakoids. • Pyrenoid-structure associated with chloroplast. Contains RUBP Carboxylase, proteins and carbohydrates. • Eye-spot=part of chloroplast. Directs the cell towards light.
Reproduksi Algae
Sistem reproduksi alga tidak dilengkapi jaringan sel-sel steril yang berfungsi melindungi sel-sel fertil, sebaliknya semua sel berpotensi untuk menjadi fertil dan menghasilkan keturunan. Embrio tidak dibentuk di dalam suatu jaringan pelindung khusus yang dihasilkan induk. Algae dapat bereproduksi secara vegetatif, seksual dan aseksual
REPRODUCTION OF ALGAE
Sexual-Gametes Vegetative Cell divisions/Fragmentation =part of the filament breaks off from the rest and forms a new one.
Asexual Reproduction Zoospores after losing their flagella, form new filaments. No sexual fusion.
SEXUAL REPRODUCTION
ISOGAMY-Both gametes have flagella and similar in size and morphology.
ANISOGAMY-Gametes have flagella but are dissimilar in shape and size. One gamete is distinctly smaller than the other one.
OOGAMY-gamete with flagella (sperm) fuses with a larger, non flagellated gamete (egg).
SEXUAL REPRODUCTION (CONTINUED)
isogamy = equal - sized motile gametes
anisogamy = motile gametes equal-sized
almost
oogamy = Small motile male gamete with large non motile female gamete
Life cycle
Most algae form some sort of spore often motile Algae also have sex, often a very simple kind of sex where the algae themselves act as gametes Sometimes very complicated with egg and sperm-like cells.
Distribution of Seaweeds • Most species are benthic where it is attached to the ocean floor • Benthic seaweeds can be found on the inner continental shelf, where they provide food and shelter to the community of organisms • Pelagic species are free floating in the ocean and are driven by currents • Distribution depends primarily by light and temperature
Inter-algal competition intense
light space nutrients
Special adaptations
Many species with rapid growth (up to 0.5 m/day) Toughness: leathery, flexible Coralline red algae CaCO3 cell walls endure waves pounding Tolerant of extremes Cold/hot Dry/wet Turbulence/currents/waves Shading
Klasifikasi Algae
Klasifikasi alga tidak semata-mata didasarkan pada persamaan ciri morfologi, tetapi lebih berdasarkan sifat pigmentasinya. Klasifikasi alga cukup beragam, meskipun secara tradisional kebanyakan hanya didasarkan pada bentuk morfologi sel-sel reproduksi, jenis pigmen fotosintesis dan jenis cadangan makanan. Di samping kloroplas, alga juga mengandung kromoplas (kromatofor) yang berbeda-beda tergantung divisinya.
Salah satu model klasifikasi alga Algae
Euglenoids
Create green and opaque water problems in aquariums.
Diflagellates
Major producer in marine ecosystems Zooxanthellae; toxic blooms (Red tides)
Diatoms
Golden Algae
Brown Algae
Major component of Ocean’s minute plankton
Ecological importance in cooler ocean water
Green Algae
Red Algae
Ecological importance in tropical ocean Reef building
Klasifikasi Chapman dan Chapman (1973) Salah satu model klasifikasi alga yang banyak diikuti. Alga menjadi sepuluh divisi, yaitu: Bacillariophyta Chloromonadophyta Chrysophyta Cryptophyta Euglenophyta Pyrrophyta Xanthophyta Chlorophyta Phaeophyta Rhodophyta
DIVERSITY IN ALGAE MORPHOLOGY MICROSCOPIC Unicellular, Colonial and Filamentous forms.
Unicellular Algae: Dinoflagellates
Two flagella that spin the cells Covered by cellulose plates Most are marine plankton, but they are common in fresh water habitats as well; their populations are distributed depending on temperature, salinity, or depth. Being primary producers make them an important part of the aquatic food chain. Can be free living or in a symbiotic relationship with jellyfish and other organisms that live near coral reefs Gonyaulax: toxic species that causes red tide (an overabundance of these – can be as many as 40-60 million per litre of seawater). The toxins produced during a red tide may make humans ill.
Euglenoids
The Euglenoids are one of the bestknown groups of flagellates, commonly found in freshwater especially when it is rich in organic materials, with a few marine and endosymbiotic members.
Many euglenoids have chloroplasts and produce energy through photosynthesis
They can move around like an animal with flagellates.
Multicellular Algae • Seaweeds are multicellular algae that inhabit the oceans • Major groups of macroalgae are mostly benthic organisms that are divided into three major groups according to their photosynthetic pigments: – green algae (Divisio Chlorophyta) – red algae (Divisio Rhodophyta) – brown algae (Divisio Phaeophyta)
Main groups of alga
Green algae (most freshwater algae – some marine; 7000 species) Brown algae (kelps; 2000 species) Red algae (includes coralline algae; 6000 species)
Pigmen Fotosintesis Algae Sistem fotosintesis alga berdasarkan pada klorofil a, namun secara keseluruhan pigmen kloroplas Chlorophyta, Rhodophyta dan Phaeophyta berbeda-beda. Klorofil a juga terdapat pada Bryophyta, Pterydophyta dan tumbuhan tingkat tinggi, tetapi strukturnya jauh lebih kompleks. Kloroplas Chlorophyta mengandung klorofil a, b dan karotenoid, sama dengan Euglenophyta dan tumbuhan tingkat tinggi. Kloroplas Rhodophyta mengandung klorofil a dan d. Kloroplas Phaeophyta mengandung klorofil a dan c.
Each group limited by its photosynthetic pigments
Green algae -- limited to near surface
Brown algae -- fairly deep – Phycobilins capture GREEN light
Red algae – capable of deepest – Phycoerythrin captures GREEN light best
Increasing depth
– Chlorophyll captures BLUE & RED light
Cadangan Makanan Alga dapat menyimpan cadangan makanan seperti kebanyakan tumbuhan lain. Cadangan makanan Chlorophyta berupa pati yang disimpan dalam kloroplas. Suatu sifat yang sangat unik mengingat semua eukaryota fotosintetik lain menyimpan cadangan makanan di luar kloroplas. Cadangan makanan Rhodophyta berupa pati/tepung floridean, suatu polimer yang menyerupai gugus amilopektin pada pati (bukan gugus amilosa) dan mirip glikogen. Cadangan makanan Phaeophyta berupa mannitol (alkohol) dan laminarin, suatu polimer glukosa yang ikatannya tidak seperti ikatan pada pati.
Economic Importance of Algae
Algae are primary producers, they are the start of the food chain. Phytoplankton are responsible for more than 45% of the Earth's annual primary production. Seaweeds are used as fertilizers and even food (by the Japanese, Irish) Extracts from the cell walls of algae (typically brown & red algae) provide the polysaccharides agar and carageenan. These are used as thickening agents in food, in surgical dressings and in microbial media. Algae help build reefs. Marine algae supply shelter for many marine organisms.
Primary producers
Most are AUTOTROPHS
make their own food
PHOTOSYNTHETIC
sunlight is essential
Role in providing habitat
Holdfast communities increase surface area for smaller organisms
Role in providing habitat
Other surface area increases – Epiphytes:
Surface of stipe Surface of blades
– Interior of bladders (salt sac copepods)
Break-up turbulence/provide shelter Provide shade for sensitive organisms
What good is it to us?
Conditioners in: – Toothpaste – Ice cream – Cosmetics – Agar – Carrageenan Food Dietary supplements Livestock, fish feed Fertilizer
More uses….
chocolate additive in instant food drinks emulsifier, to give certain foods a smooth consistency serves as a binder to keep mixture intact surgical jellies, demulcents, and anti-acid tablets checking hepatitis curing ulcer natural latex creaming and thickening for rubber sizing for textiles, toothpastes, and brake fluids adhesive for paper bags and gummed tapes coating for food packages and milk containers ceramic glazes, leather finishes, broiler compounds, battery plate separators, beet sugar processing, wax and emulsions; and additive in the preparation of fertilizer and pesticides
