Biology
The fronds and air-bladders of Macrocystis pyrifera © David M John
Macrocystis pyrifera has 2 life history stages:
- the very distinctive macroscopic stage
- a microscopic filamentous stage
The microscopic stage (gametophyte) is either male or female and produces eggs and sperm which fertilize and give rise to the macroscopic stage (sporophyte).
The spores are produced by meiosis in sporangia grouped together on the surface of the lower fronds of the macroscopic stage and these release biflagellate zoospores that settle and germinate into the microscopic stage.
The macroscopic stage is perennial with its holdfasts surviving from 4 to 10 years and the fronds from 6 to 12 months. The life span is sometimes shortened to just 1 or 2 years on exposed coasts.
Toolbox
Glossary
Abalone
Edible sea snails.
Alginates
A compound rendered from seaweed that can be used to make temporary casts.
Fronds
Leaf-like parts of the seaweed.
Holdfasts
Root-like structures that anchors the seaweed to a substrate.
Macroscopic
A size large enough to be visible with the naked eye.
Microscopic
A size so small that is only visible with a lens or microscope.