What is a kelp holdfast?

A root-like base gripping rocks

What are urchin barrens?

Areas where urchins have destroyed kelp

What is kelp used for?

Food, alginate thickeners and fertilizer

Kelp Forests Quiz: Places, People and Key Facts

This kelp forests quiz covers giant kelp growth, holdfasts and gas bladders, sea otters and urchins, the Great Southern Reef and Great African Seaforest, kelp loss from warming and kelp farming. Ten questions test what you know about underwater forests.

Start Kelp Forests Quiz

🎯 Daily Trivia Challenge • 🧠 10 Questions • ⏱️ 150 Seconds

Question 1 / 10 Time: 150s

Type
What is kelp?
Speed
How fast can giant kelp grow?
Holdfast
What is a kelp holdfast?
Float
What keeps kelp upright?
Otters
How do sea otters help kelp forests?
Barrens
What are urchin barrens?
Water
Where do kelp forests grow best?
Africa
Which kelp forest was featured in My Octopus Teacher?
Loss
Where has more than 90% of kelp forest been lost in parts of the coast?
Uses
What is kelp used for?

Explanations: answer key for all 10 questions

Q1: What is kelp?
Answer: A large brown algae
It is not a true plant.
Q2: How fast can giant kelp grow?
Answer: Up to about 60 cm a day
It is one of the fastest-growing organisms.
Q3: What is a kelp holdfast?
Answer: A root-like base gripping rocks
It does not absorb nutrients.
Q4: What keeps kelp upright?
Answer: Gas-filled bladders
They lift blades toward the sunlight.
Q5: How do sea otters help kelp forests?
Answer: They eat sea urchins
They are a keystone species.
Q6: What are urchin barrens?
Answer: Areas where urchins have destroyed kelp
They can last for decades.
Q7: Where do kelp forests grow best?
Answer: Cool, nutrient-rich coastal waters
Warming harms them.
Q8: Which kelp forest was featured in My Octopus Teacher?
Answer: The Great African Seaforest
It lies off South Africa.
Q9: Where has more than 90% of kelp forest been lost in parts of the coast?
Answer: Northern California
A marine heatwave and urchins caused it.
Q10: What is kelp used for?
Answer: Food, alginate thickeners and fertilizer
Kelp farming is growing.

Kelp Forests Quiz – Forests Under the Sea

Kelp forests are underwater forests of large brown algae that grow in cool, nutrient-rich coastal waters. Giant kelp can grow up to about 60 centimeters a day, forming tall canopies held up by gas-filled bladders and anchored by holdfasts.

These forests shelter fish, seals, sea stars and countless invertebrates. Sea otters keep them healthy by eating sea urchins, which otherwise can mow kelp down and create barren areas.

Kelp forests are threatened by warming seas, marine heatwaves and urchin booms. Northern California lost most of its kelp after 2014. Restoration projects, otter recovery and kelp farming offer hope, and kelp also absorbs carbon.

What This Quiz Teaches

This quiz is for students exploring kelp forests.

What kelp is
How fast it grows
How otters help
What urchin barrens are
What threatens kelp

Did You Know?

Kelp forests line about a quarter of the world's coasts.
Sunflower sea star losses fueled urchin booms.
Tasmania lost most of its giant kelp.
Kelp is used in ice cream.
The Great Southern Reef lines southern Australia.