- Not a plant, but a species of brown algae.
- Tall vertical alga/seaweed, green-brown in coloration.
- Each ridged leaf blade has a gas-filled pod at the base that floats, helping keep the kelp vertical.
- No roots, instead attached to the rocks by a structure called a holdfast.
- Can reach heights of 100 feet tall.
- When it reaches the sea surface, it continues to grow horizontally.
- From Santa Cruz, California to Turtle Bay, Mexico.
- Along the temperate coasts of South America, New Zealand, and Australia.
- Found in cold, clear saltwater.
- Found on rocky reefs up to 100 feet below the sea surface.
- Reproduction occurs through alternation of generations.
- The large kelp forms spores that are released into the water.
- These spores become microscopic female and male stages of kelp.
- When the male stage (sperm) fertilizes the female stage (egg) in the water, it becomes a tiny plant called a sporophyte.
- This sporophyte anchors itself to the bottom using its holdfast.
- This sporophyte grows into the large kelp frond that can produce spores again.
- Uses the sun to get its energy through a process called photosynthesis.
- Bristle worms, scud, prawns, snails, and brittles stars eat the holdfasts.
- Opaleye and halfmoon fish eat kelp blades.
- Purple sea urchins can devastate a kelp forest if left unchecked.
- Giant kelp is the largest seaweed in the world and the largest of all marine algae..
- It is one of the fastest-growing species in the world, and can grow up to two feet in a day!
- When a lot of giant kelp is together, it creates a dense forest that is home to many species of fish, sharks, lobsters, squids, otters, sea stars, and other creatures.
Sources: Oceana; Monterey Bay Aquarium; National Ocean Service; California Department of Fish and Wildlife; US National Park Service; University of Southern Florida
Photo: Howard Hall
Look at live kelp in person anytime on Birch Aquarium’s Kelp Cam!