Nereocystis luetkeana
Bull kelp
Brown seaweeds, like this kelp, are a distinct group and have a separate ancestor to all other seaweeds. Kelps are usually made up of a holdfast, stipe, and blade(s).
Most algae live in water, and even though many photosynthesize to make their own food, only some of them are classified as plants. Seaweeds are macroalgae (algae large enough to see without a microscope) that live in the ocean and can be described as red, green, or brown.
Bull kelp
Brown seaweeds, like this kelp, are a distinct group and have a separate ancestor to all other seaweeds. Kelps are usually made up of a holdfast, stipe, and blade(s).
Bull kelp
on rock
on unidentified substrate
on shell
on rock
on shells
Corallines are a special group of red algae containing calcium carbonate. You can see two types here, crustose coralline algae (pink bubblegum crusts) and articulated coralline algae (upright, segmented, and branching).
on bottle
on rock
Look closely. Can you see some crustose coralline on this articulated coralline? The crust is probably Neopolyporolithon reclinatum, a picky species which only grows on articulated corallines.
on rock
Do you know your delicate sea lace from your coarse sea lace? Seaweeds can be tricky to identify, so researchers use many tools including online keys and identification apps.
Teal nori
Teal nori
Sea palm kelp
Sea palm kelp
Black seaweed
You can find seaweeds in many different habitats. Some, like this rockweed and feather boa kelp, grow near rock pools along the shore. Others grow in deeper waters and reach up to the surface to photosynthesize. A few inflate with air to float on the surface of the ocean.
Feather boa kelp
Sea lettuce
Rockweed
Rockweed
Common eelgrass
This might look like a seaweed, but it is actually an underwater flowering plant. Try searching for it next time you walk along a beach at low tide.