The water net (

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

''Hydrodictyon'') is a taxon of freshwater green algae in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Hydrodictyaceae Hydrodictyaceae is a family of green algae in the order Sphaeropleales. Genera * '' Euastropsis'' * '' Helierella'' * '' Hydrodictyon'' * '' Lacunastrum'' * '' Monactinus'' * '' Parapediastrum'' * ''Pediastrum ''Pediastrum'' is a genus of ...

. ''Hydrodictyon'' does well in clean,

eutrophic Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients, particularly nitrogen and phosphorus. It has also been defined as "nutrient-induced increase in phytoplan ...

water, and has become a nuisance in

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

, where it has been recently introduced. The name ''water net'' comes from the (usually pentagonal or

hexagon In geometry, a hexagon (from Greek , , meaning "six", and , , meaning "corner, angle") is a six-sided polygon. The total of the internal angles of any simple (non-self-intersecting) hexagon is 720°. Regular hexagon A '' regular hexagon'' has ...

al) mesh structure of their colonies, which can extend several decimeters.

Reproduction in hydrodictyon

Algae in the genus can reproduce asexually or

sex Sex is the trait that determines whether a sexually reproducing animal or plant produces male or female gametes. Male plants and animals produce smaller mobile gametes (spermatozoa, sperm, pollen), while females produce larger ones ( ova, of ...

ually. Asexual reproduction takes place by biflagellated (having two flagella)

zoospore A zoospore is a motile asexual spore that uses a flagellum for locomotion. Also called a swarm spore, these spores are created by some protists, bacteria, and fungi to propagate themselves. Diversity Flagella types Zoospores may possess one or ...

s formed by the thousands inside a cell. However, the zoospores hardly move, as they are packed very densely. The zoospores form a cell wall, become cylindrical in shape, and arrange themselves in a hexagonal pattern, much like the mature tissue. The mother cell disintegrates, releasing the

microscopic The microscopic scale () is the scale of objects and events smaller than those that can easily be seen by the naked eye, requiring a lens or microscope to see them clearly. In physics, the microscopic scale is sometimes regarded as the scale be ...

daughter net. During sexual reproduction, which takes place by iso-

gamete A gamete (; , ultimately ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce ...

s (gametes of the same size) even smaller than the zoospores, the iso-gametes escape through a hole in the cell wall of the mother cell. Two gametes fuse, forming a

zygote A zygote (, ) is a eukaryotic cell formed by a fertilization event between two gametes. The zygote's genome is a combination of the DNA in each gamete, and contains all of the genetic information of a new individual organism. In multicell ...

, which then develops a thick cell wall and becomes angular in shape. After a rest period, 2-5 zoospores, which are bigger than the ones formed by asexual reproduction, are produced. The zoospores then enlarge into polygonal cells. The

cytoplasm In cell biology, the cytoplasm is all of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. ...

of the cells then divide into new zoospores which lose their flagella and form a new net by lying against each other.

External links

Hydrodictyon on the Protist Information Server
* ttp://www.mic-d.com/gallery/brightfield/hydrodictyon.html Microscopic viewbr>Entry in the Global Compendium of Weeds
{{Taxonbar, from=Q1508605 Sphaeropleales