Reef Structure
Cnidarians
Porifera
Ecology and Biodiversity
Threats
100

According to atoll theory, coral reefs begin forming around this type of landform.

What is a volcanic island?

100

This free-swimming, bell-shaped body form has the mouth facing downward.

What is a medusa?

100

The central cavity of a sponge through which water flows is called this.

What is the spongocoel?

100

These organisms make their own food using sunlight and form the base of reef food webs; examples include algae and phytoplankton

What are primary producers?

100

Rising ocean temperatures caused by this global environmental change are a major threat to coral reefs.

What is climate change?

200

This part of the reef receives the strongest wave action and forms the outer ridge of the reef.

What is the reef crest?

200

This type of reproduction occurs when polyps produce new individuals by budding.

What is asexual reproduction?

200

Sponges can also reproduce asexually by this method, producing small buds or internal survival

 What are budding or gemmules?

200

These reef animals eat producers like algae; examples include parrotfish and sea urchins.

What are primary consumers?

200

This process happens when stressed corals expel the algae living in their tissues, causing them to turn white.

What is coral bleaching?

300

The chemical formula CaCO₃ represents this compound that makes up most coral reef structures.

What is calcium carbonate?

300

This class of cnidarians includes corals and sea anemones and exists only in the polyp stage.

What is Anthozoa?

300

This sponge feeding strategy uses specialized cells called choanocytes to pull water through pores and trap tiny food particles

What is filter feeding

300

These reef predators eat herbivores like small fish or invertebrates; examples include wrasses and small reef fish.

What are secondary consumers?

300

Chemicals from this common beach product can harm coral reefs and contribute to coral damage.

What is sunscreen?

400

Coral reefs require fairly stable levels of this property of seawater, usually around 34–37 parts per thousand.

What is salinity?

400

This bell-shaped structure contracts rhythmically to move jellyfish through the water.

What is the bell?

400

In sponges, these flagellated cells line the internal chambers and create water currents that trap food particles

What are choanocytes

400

These top reef predators feed on secondary consumers and help control the ecosystem; examples include barracudas and reef sharks.

What are tertiary consumers?

400

This agricultural runoff containing nutrients can wash into oceans and cause harmful algae growth that damages reefs.

What is fertilizer runoff?

500

High levels of this water condition—caused by suspended sediments—reduce sunlight and harm reef growth.

What is turbidity?

500

This internal cavity is where digestion occurs in jellyfish.

What is the gastrovascular cavity?

500

This class of sponges contains skeletons made primarily of silica spicules and spongin fibers and includes about 90% of all sponge species

What is Demospongiae

500

These organisms break down dead plants and animals on the reef, recycling nutrients; examples include bacteria, marine worms, and crabs.

What are decomposers or scavengers?

500

This natural weather event can break apart coral reefs with strong waves and increased storm severity.

What are storms or hurricanes?