Exploring the Intertidal

Check out the intertidal zone and its biodiversity!

Phaeophyta

This phylum includes the brown algae, and is almost exclusively marine. All phaeophyte species in this group are multi-cellular. The giant kelps also belong to this group. These amazing algae can grow a metre in length in a couple of weeks, and dozens of metres in a single year! This group contains the pigments chlorophyll a and c and fucoxanthins. Most brown algae are found in the intertidal or shallow subtidal, and they are more abundant in the Northern Hemisphere. Kelp are becoming very important commercially: for food, cosmetics, pharmaceuticals and in the sciences.

A kelp can easily be identified by four basic structural components (three shown on left): blade/frond (photosynthetic portion), bulb (used as a float to keep blades near light at the surface; only present in some species), stipe (analogous to a stem in vascular plants), and holdfast (root-like or disk-shaped; attaches the kelp firmly to the substrate) (for more on brown algae, click here).

Egregia menziesii (Feather Boa Kelp)
Description: Small branches and floats off either side of thick stipe.
Range: British Columbia to California.
Habitat: Exposed, rocky shores. Low intertidal to upper subtidal.
Cool Fact: Used as fertilizer by coastal farmers!

 Fucus gardneri (Rockweed)
Description: Green to brown. Dichotomous branching. Swollen receptacles at end. Midrib present.
Range: Alaska to California.
Habitat: Attached to rocks. Mid to low intertidal. Often the most common intertidal algae on B.C. shores. It is difficult to miss!
Cool Fact: The receptacles contain the gametes, which are released after a period of desiccation. A hardy algae - capable of tolerating extreme physical conditions!

Laminaria setchellii (Split Kelp)
Description: Brown to black. Smooth blade with a split down the centre.
Range: Alaska to California.
Habitat: Very exposed rocky shores. Low intertidal to upper subtidal.
Cool Fact: This algae can survive the high velocity and heavy turbulence found in surge channels!

Leathesia difformis (Sea Cauliflower)
Description: Yellow. Hollow, convoluted and spongy.
Range: Bering Sea to Mexico.
Habitat: Rocky shores. Sometimes epiphytic. All intertidal zones.
Cool Fact: Originally thought to be a jelly fungus!

Macrocystis integrifolia (Giant Kelp)
Description:Blades branch along length of stipe. Small float at the base of each blade.
Range: Alaska to California.
Habitat: Rocky shores. Low intertidal to 10m deep.
Cool Fact: This kelp grows incredibly fast - 20cm in only a few days! Also important because herring lay their row on this kelp.

Nereocystis luetkeana (Bull Kelp)
Description:Long stipe with bulb and long fronds at one end.
Range: Alaska to California.
Habitat: Rocky shores. Upper subtidal and lower.
Cool Fact: One of the largest kelps! An annual alga that can grow 25m or more in a single year! The float is filled with carbon monoxide to keep the blades at the surface.

see more about Phaeophyta!

  to Intertidal Field Guide directory