Question

A rigid, wave-resistant structure built by corals from skeletal materials is A. an estuary. C. a beach. B. a reef. D. a rocky shore.

Short answer

The correct answer is B. a reef.

Step-by-step solution

Identify the Definitions

Understand the key terms provided in the options. An estuary is a coastal water body where fresh water from rivers meets the sea. A beach is a landform along the coast of an ocean, sea, lake, or river, consisting of sand, pebbles, or other sediment. A reef is a ridge of jagged rock, coral, or sand just above or below the surface of the sea. A rocky shore is a coastal area with rocky land exposed to the sea.

Recall Coral Structures

Recall that corals are marine organisms with a hard, calcareous skeleton, which they use to construct wave-resistant structures. These structures are built from the skeletal material secreted by corals.

Match Definitions to the Structure

Match the structure described in the question with the correct definition from the options. A rigid, wave-resistant structure built by corals is consistent with the definition of a 'reef' as corals form reefs.

Confirm the Correct Option

Review the remaining options to ensure none of them fit the description better than the chosen one. An estuary, a beach, and a rocky shore do not involve coral construction, confirming that the correct answer is a reef.

Key concepts

marine biology

Marine biology is the study of organisms in the ocean and other saltwater environments. One of the key features of marine biology is the study of coral reefs. Corals are fascinating marine animals that live in compact colonies of many identical individual polyps. They belong to the group of organisms called cnidarians, which also includes sea anemones and jellyfish.
Coral reefs, known for their incredible biodiversity, serve as home to around 25% of all marine life. These ecosystems are often likened to underwater rainforests due to their rich biodiversity. Reef-building corals secrete calcium carbonate to form a hard skeleton that provides structure to the reef. This structure not only supports the countless species residing there but also offers protection to coastal regions by absorbing wave energy.

• Corals obtain nutrients from sunlight and zooplankton.
• Many corals have a symbiotic relationship with algae called zooxanthellae.
• Threats to coral reefs include climate change, pollution, and overfishing.

Learning about marine biology allows us to understand the delicate balance of ocean ecosystems and the critical role coral reefs play in maintaining this balance.

coastal ecosystems

Coastal ecosystems are thriving, diverse environments found along the shores. These ecosystems include coral reefs, estuaries, beaches, salt marshes, and mangrove forests. Each plays a unique role in maintaining ecological balance and supporting life.
Coral reefs are a key part of coastal ecosystems. They help protect coastlines from erosion by acting as natural breakwaters. Reefs provide nursery areas for many marine organisms, which, in turn, support fisheries that countless communities depend on for food and livelihood.

• Estuaries are highly productive zones where freshwater mixes with seawater.
• Beaches offer habitats for flora and fauna, from nesting sea turtles to shorebirds.
• Mangroves are critical for stabilizing coastlines and improving water quality.

Understanding coastal ecosystems is essential for their conservation, as these areas are often under threat from human activities such as development and pollution.

marine geology

Marine geology is the study of the composition and processes behind the ocean floor and coastal landforms. This field examines how structures like coral reefs, sandy beaches, and rocky shores are formed and transformed.
Reef-building corals are key geological architects in marine geology. These tiny organisms extract calcium carbonate from seawater to produce limestone structures that form the basis of coral reefs. Over thousands of years, these reefs can create large limestone deposits, contributing significantly to the geological landscape.

• Rocky shores are shaped by waves, which erode and carve the land into various formations.
• Sandy beaches result from sediment brought from rivers and the action of ocean currents.
• Marine geology helps track changes in sea level, which affects coastal ecosystems.

Through marine geology, we gain insights into natural processes that have shaped our planet's coastal and underwater landscapes over millennia.