What is the difference between algae and seaweed

This collection of Porphyra sp. Share this: Facebook Twitter Email. Like this: Like Loading Leave a Reply Cancel reply Enter your comment here Fill in your details below or click an icon to log in:.

Email required Address never made public. Name required. Follow Following. Canadian Museum of Nature Blog Join other followers. Sign me up. Already have a WordPress. Log in now. Although most algae are autotrophs , some of them can be heterotrophs. Of these, autotrophic algae contain chlorophyll and undergo photosynthesis. Hence, photosynthetic algae serve as primary producers of most of the aquatic food chains. Figure 1: Algae on the Seabed.

Furthermore, the three divisions of algae are Chlorophyta green algae , Rhodophyta red algae , and Phaeophyta brown algae. Basically, they differ by the combinations of photosynthetic pigments present in the plant body. That is, green algae are a diverse group of algae that contain chlorophyll, beta-carotene, and xanthophyll. Meanwhile, phycoerythrin is the main type of photosynthetic pigment in red algae. On the other hand, chlorophyll c and fucoxanthin are the two main photosynthetic pigments in brown algae.

Seaweed is essentially macroalgae that exclusively grows in marine habitats. However, it has members in all three groups of algae; Rhodophyta red , Phaeophyta brown and Chlorophyta green macroalgae. Of these, brown algae, also known as dusky plants, are the most common type of seaweeds. And, these have a brown or yellow-green in color. Search only containers. Search titles only.

Search Advanced search…. Members Current visitors. Interface Language. Log in. Install the app. In the former, the seaweed produces gametes egg and sperm cells with a single set of chromosomes and, in the latter, spores containing two sets of chromosomes.

Some species can also reproduce asexually by fragmentation—that is, the blades shed small pieces that develop into completely independent organisms. The the red alga Porphyra , used for making Japanese nori, has a highly complex life cycle.

Asexual reproduction allows for fast propagation of the species but carries with it an inherent danger of limited genetic variation. Sexual reproduction ensures better genetic variation, but it leaves the species that depend on this method of reproduction with an enormous match-making problem, as the egg and sperm cells need to find each other in water that is often turbulent.

Some species solve the match-making problem by equipping the reproductive cells with light-sensitive eyespots or with flagella so that they can swim.

Others make use of chemical substances, known as pheromones or sex attractants. These are secreted and released by egg cells and serve to attract the sperm. Some species for example, the large seaweed masses in the Sargasso Sea secrete enormous quantities of slime, which ensures that the egg and sperm cells stick close to each other and do not go astray. A newly discovered species of red seaweed is now named Porphyra migitae. The red alga Porphyra has an especially complicated life cycle, with a fascinating aspect that merits further discussion because of the interesting history associated with its discovery.

It relates directly to the cultivation of Porphyra for the production of nori, which is especially widely used in Japanese cuisine—most familiarly, as for the wrapping for maki rolls See the recipe in the caption for the nori roll image below.

The blades used in nori production grow while the seaweed is in the generation that reproduces sexually, although the organism itself can actually develop asexually from spores.

The blades produce egg cells and sperm cells. The egg cells remain on the blades, where they are fertilized by the sperm cells. The fertilized eggs can then form a new type of spores, which are released. These spores germinate into a calcium-boring filament stage that can grow in the shells of dead bivalves, such as oysters and clams, in the process developing spots that give the organism a pinkish sheen.

Until the s it was thought that this sexual stage was actually an entirely separate species of alga, given the name Conchocelis rosea. Without an understanding of the true life cycle, it was not possible to grow Porphyra effectively in aquaculture. No one knew where the spores for the fully grown Porphyra originated. This was the main reason for the recurring problems experienced by the Japanese seaweed fishers in their attempts to cultivate Porphyra in a predictable manner.

It was an English alga researcher, Dr. Kathleen Mary Drew-Baker, who discovered the secret of the sexual segment of the Porphyra life cycle. Drew-Baker was unaware of the difficulties of the seaweed fishers.

Instead, she was preoccupied with shedding light on the mystery of why the species of laver Porphyra umbilicalis that grew around the coast of England seemed to disappear during the summer, reappearing again only toward the end of autumn. She tried without success to germinate spores that she had collected. They would even grow on an eggshell. A few months later, the resulting small, roseate sprouts produced their own spores that, in turn, could germinate and develop into the well-known large purple laver.

Drew-Baker published her results in Shortly thereafter the Japanese phycologist Sokichi Segawa repeated her experiments using local varieties of Porphyra and found that they behaved in the same way as the English species.

The mystery was solved and the results were quickly put to use in Japan. Drew-Baker died at a relatively young age in , apparently unaware that her curiosity and seminal research had laid the foundations for the development of the most valuable aquaculture industry in the world.

As in green plants, photosynthesis enables seaweeds to convert sunlight into chemical energy, which is then bound by the formation of the sugar glucose.

The photosynthetic process uses up carbon dioxide, which is thereby removed from the water. In addition, phosphorous, a variety of minerals, and especially nitrogen are required. Oxygen is formed as a by-product, dissolved in the water, and then released into the atmosphere. This by-product is of fundamental importance for those organisms that must, like humans, have oxygen to be able to breathe. Photosynthesis can even, to a certain extent, be carried out when seaweeds are exposed to air and partially dehydrated.

They now run Maine Coast Sea Vegetables, a company which has its own building and 20 employees who transform the locally harvested seaweeds into more than 20 different products. The raw material for this business is delivered by about 60 seaweed harvesters who work along the coasts of Maine and Nova Scotia, where algae are found in abundance. Shep trains the harvesters himself. It is of utmost importance to him that they understand the principles of collecting the different types of marine algae sustainably so that they do the least harm to the environment.

Maine Coast Sea Vegetables processes about 50 tons of dried seaweeds annually, of which about 60 percent is the dulse for which the company is especially famous. Eating dulse is an old tradition in Maine, brought to its shores by settlers from Wales, Ireland, and Scotland. I have become a great fan of their applewood smoked dulse; I eat it as if it were candy. When dried dulse is brought to the factory, it is sorted by hand, and epiphytes, small crustaceans, and bivalves are picked off.

The bone-dry dulse is placed in a sealed room to reabsorb some moisture and then left to ripen for a couple of weeks. In tightly sealed packages, the chewy blades have a shelf life of about a year.

During the night, when the light level is low, photosynthesis stops and the seaweeds begin to take in oxygen, burn glucose, and give off carbon dioxide. Under normal conditions, photosynthesis is the dominant process, allowing the seaweeds to build up their carbohydrate content. To the extent that they have access to light in the water, seaweeds actually utilize sunlight more efficiently than terrestrial plants. Marine algae are a much better source of iron than foods such as spinach and egg yolks.