Vihreälevät

Vihreälevät, or green algae, are a large and diverse group of eukaryotic organisms belonging to the division Chlorophyta. They are characterized by their green color, which is due to the presence of chlorophyll a and b, the same photosynthetic pigments found in land plants. This chlorophyll allows them to perform photosynthesis, converting light energy into chemical energy.

Vihreälevät inhabit a wide range of environments, from freshwater bodies like lakes, ponds, and rivers to saltwater oceans and even terrestrial habitats such as soil, tree bark, and rocks. Some species are free-floating, while others are attached to substrates. Their forms vary greatly, encompassing unicellular organisms, colonial forms, filamentous structures, and multicellular thalli.

The ecological importance of vihreälevät is significant. As primary producers, they form the base of many aquatic food webs, providing energy for a multitude of organisms. They also play a crucial role in oxygen production in aquatic ecosystems. Some vihreälevät have symbiotic relationships with other organisms; for instance, they are integral components of lichens, forming a partnership with fungi.

Reproduction in vihreälevät can be asexual, through cell division, fragmentation, or the formation of spores, or sexual, involving the fusion of gametes. Their evolutionary history is particularly noteworthy, as they are considered the ancestors of all land plants, a transition that occurred over 500 million years ago.