Divison Phaeophyta Brown algae 1500 species 250 genera
Where are they found?
- Marine, preferably cold; agitated and aerated found on rocky coasts in the littoral zone between the region of high and low tides (intertidal zone) and are periodically exposed to air and completely exposed to sunlight at low tide.
- Also in the sublittorial if rocky and offers enough stable substrates
- Also others submersed all the time from surface to depths of 220m
What do they look like? the most complex algae anatomically and morphologically, some more complex than the mosses/liverworts. All forms are multicellular
Cell walls: cellulose, and alginic acid not found in other algae. This acid is slimy or gummy and causes the filaments of cells to adhere into a compact body. Alginic acid may have other function as some species are as much as 24% by weight of this unique compound. What other reasons could you come up with? Try these out... cut down on resistance of water hitting algae, unedibility, can you think of any others? let me know!
Specialized tissues: some species. have an epidermis like outer covering, a parenchyma-like cortex area and a cylinder of trumpet cells that resemble phloem cells so much that some people call them seive tube members. These are implicated in long distance transport of carbohydrates; elongate with large seive like arrangement in end walls; holes lined with callose. Flow rates of 65-78 cm/hr
Colors:Differ from higher plants in that they contain chlorophyll a & c and contain a number of xanthophyll pigments i.e.. fucoxanthin Also contain carotenes. This complex of pigments allows them to photosynthesize at numerous levels in the sea; similar to dinoflagellates and golden-browns. Heliobacterium ancestor of all.
Storage product: laminarian (polymer of glucose) up to 34% of body weight; also mannitols or fats but not starch. Any ideas of why not starch?
Life cycles: an example of a typical life cycle is as follows. note specialized male bearing gamete structures ( antheridium) and female or egg-bearing structures called oogonium... a common pattern we'll note through the classes to come.
Economic:
1. kelp eaten as vegetable in East; provide salts, vitamins, trace elements, Also harvested for ash (Na,K) for industry, iodine. and used as fertilizer.
2. alginates from walls used as thickening agents and colloid stabilizers in the food, textile, cosmetic. pharmaceutical, paper & welding industries.
Algin is now used in a wide range of foods including desserts, gels, milkshake mixes, dairy products and canned foods. It is used in bakery products from cake mixes to meringues to improve texture and retain moisture. Algin is used in frozen foods for its stabilizing properties to assure smooth texture and uniform thawing. It is also used to stabilize beer foam. The primary industrial applications for algin are in paper coating and sizing, textile printing and welding-rod coatings. Pharmaceutical and cosmetic applications for algin include its use in products including tableting, dental impression compounds and anti-acid formulations.
3. The entire marine sport-fishing industry depends on it to provide shelter and habitat for many game fish as well as the numerous smaller prey-items on which the game fish survive on.
