Porphyra facts for kids

{{Automatic taxobox | image = Porphyra umbilicalis, Porphyra purpurea Helgoland.JPG | image_caption = Porphyra umbilicalis (right) and Porphyra purpurea (front), found near Heligoland | image_alt = Porphyra umbilicalis (right) and Porphyra purpurea (front), in Heligoland | taxon = Porphyra | authority = C.Agardh 1824 | subdivision_ranks = Species | subdivision_ref =

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Porphyra is a type of seaweed that likes to grow in cold, shallow salt water. It's part of the red algae family and is one of the kinds of seaweed known as laver. There are about 70 different species of Porphyra around the world. You can often find it in the intertidal zone, which is the area of the coast that is covered by water at high tide and exposed at low tide. In East Asia, Porphyra is very popular and is used to make food products like nori in Japan and gim in Korea.

How Porphyra Grows: Life Cycle

Porphyra has a special way of growing called "alternation of generations." This means it has two main stages in its life that look very different.

• The seaweed you usually see is the first stage. It's called a thallus and has only one set of chromosomes (it's haploid).
• This thallus can make copies of itself by releasing tiny spores that grow into new thalli.
• It can also reproduce sexually. Both male and female parts are on the same thallus.
• The male parts release tiny male cells that swim to the female parts, which stay on the thallus.
• Once fertilized, these cells develop into special spores called carpospores.
• These carpospores settle down and grow into a completely different-looking stage. This stage is a tiny, thread-like plant that burrows into shells.
• For a long time, people thought this thread-like stage was a different type of algae called Conchocelis rosea.
• But in 1949, a British scientist named Kathleen Mary Drew-Baker discovered that Conchocelis was actually the second stage (the diploid stage, with two sets of chromosomes) of Porphyra umbilicalis. This discovery was very important for understanding how Porphyra grows.

Porphyra as Food

Many cultures around the world eat Porphyra. It's one of the most commonly used seaweeds for food. It has different names depending on where you are:

• In Great Britain and Ireland, it's called laver and used to make laverbread.
• In Japan, it's known as nori (海苔) or amanori.
• In Korea, it's called gim (김).
• In China, it's known as zǐcài (紫菜).
• In Hawaii, a species called P. atropurpurea is a special treat called Limu luau.

Porphyra is grown on farms in many Asian countries. It's famous for being used to wrap sushi in Japan and gimbap in Korea. The seaweed farming industry for Porphyra in Japan is worth a lot of money, around US$1 billion each year! Native peoples along the North American Pacific coast, like the Southern Kwakiutl and Haida, also traditionally harvested Porphyra for food.

Porphyra and Vitamin B12

Porphyra does contain some Vitamin B12. However, it's not enough to be a main source of this vitamin for people who follow a vegan diet.

Different Types of Porphyra

For a long time, there were about 70 species of seaweed in the Porphyra group. But in 2011, scientists did a big study and decided to move many of these species to a new group called Pyropia.

For example, species like Pyropia tenera, Pyropia yezoensis, and New Zealand's Pyropia rakiura and Pyropia virididentata are now in the Pyropia group. This means that only about five species are still officially part of the Porphyra genus today.

See also

In Spanish: Porphyra para niños