Monterey Bay Aquarium Research Institute
Marine Botany

Enteromorpha Life History

UPDATE: Enteromorpha: synonymous with the genus Ulva

See Linnaeus was right all along: Ulva and Enteromorpha are not distinct genera. in Eur. J. Phycol (August 2003) 38: 277-293.

Like many algae, Enteromorpha alternates between asexual and sexual life stages. Both life stages are very similar morphologically. However, the sporophyte has two sets of chromosomes, denoted as 2N, while the gametophytes have only one set of chromosomes (1N).

As shown in the following diagram, through mitosis, gametes (sexually reproductive cells) are produced by gametophytes, and then they join together and grow into a sporophyte. The sporophyte then undergoes meiosis, producing zoospores (asexual reproductive cells), and each zoospore grows into a gametophyte. The gametophyte then produces more gametes, and the cycle continues.

Enteromorpha is dioecious, meaning it has separate sexes. In addition, Enteromorpha can be isogamous or anisogamous, in other words, the male and female gametes can be the same size or they can be different sizes. However, even thought the gametes are sometimes different sizes, it is difficult to tell the male and female gametophytes apart because they have similar morphologies, and neither sex has specialized reproductive bodies. Both gametes and zoospores are released from the tips of the fronds, and when fertile the tips become colored orange-yellow in males and yellow-green in females.

Some lonely gametes looking for love.

The gametes are starting to find each other and clump together.

Any of the cells in a frond are capable of producing gametes. Gametes have two flagellae, which enables them to swim. Spores, on the other hand, have four flagellae. Gametes are unable to survive for long periods after being released if they do not find another gamete or a place to grow. Zoospores, however, are able to live for as long as eleven months without growing if they are subjected to an adverse environment.

 

Last updated: Feb. 05, 2009