Algae

Algae (/ˈældʒiː/ or /ˈælɡiː/; singular alga /ˈælɡə/) is an informal term for a large, diverse group of eukaryotes that are not necessarily closely related and are thus polyphyletic. Included organisms range from unicellular genera, such as Chlorella and the diatoms, to multicellular forms, such as the giant kelp, a large brown alga that may grow up to 50 meters in length. Most are aquatic and autotrophic and lack many of the distinct cell and tissue types, such as stomata, xylem and phloem, that are found in land plants. The largest and most complex marine algae are called seaweeds, while the most complex freshwater forms are the Charophyta, a division of green algae that includes, for example, Spirogyra and the stoneworts.

There is no generally accepted definition of algae. One definition is that algae "have chlorophyll as their primary photosynthetic pigment and lack a sterile covering of cells around their reproductive cells". Some authors exclude all prokaryotes and thus do not consider cyanobacteria (blue-green algae) as algae.

List of craters on Mars: A-G

This is a list of craters on Mars. There are hundreds of thousands of impact craters on Mars, but only some of them have names. This list here only contains named Martian craters starting with the letter A – G (see also lists for H – N and O – Z).

Large Martian craters (greater than 60 km in diameter) are named after famous scientists and science fiction authors; smaller ones (less than 60 km in diameter) get their names from towns on Earth. Craters cannot be named for living people, and small crater names are not intended to be commemorative - that is, a small crater isn't actually named after a specific town on Earth, but rather its name comes at random from a pool of terrestrial place names, with some exceptions made for craters near landing sites. Latitude and longitude are given as planetographic coordinates with west longitude.

A

B

C

D

E

F

G

See also

References

External links

Alga (disambiguation)

Some places named Alga are:

Burkina Faso

Italy

Kazakhstan

Kyrgyzstan

See also