Corals

Definition

Corals are marine invertebrates that belong to the class Anthozoa within the phylum Cnidaria. They form large, calcium carbonate structures known as reefs, which are essential for marine biodiversity and ecosystem stability. Corals play a vital role in biomineralization by extracting calcium and carbonate ions from seawater to create their hard skeletons, contributing significantly to oceanic carbon cycling and habitat formation.

5 Must Know Facts For Your Next Test

1. Corals can reproduce both sexually and asexually, allowing them to maintain and grow their populations under various environmental conditions.
2. Coral reefs are one of the most diverse ecosystems on Earth, supporting around 25% of all marine species despite covering only about 1% of the ocean floor.
3. The symbiotic relationship between corals and zooxanthellae is crucial for their survival, as the algae provide energy to corals through photosynthesis, especially in nutrient-poor waters.
4. Coral reefs are highly sensitive to changes in temperature, acidity, and pollution, making them vulnerable to climate change and other anthropogenic impacts.
5. Corals contribute to the global carbon cycle by sequestering carbon in their skeletons, which can influence ocean chemistry and help mitigate atmospheric CO2 levels.

Review Questions

• How do corals utilize biomineralization to form their skeletons, and what is the significance of this process for marine ecosystems?
  • Corals utilize biomineralization by extracting calcium and carbonate ions from seawater to build their hard calcium carbonate skeletons. This process is significant as it not only creates the structural framework for coral reefs but also supports diverse marine ecosystems. The reefs provide habitat and food for countless marine organisms, playing a crucial role in maintaining biodiversity and ecosystem services in the ocean.
• Discuss the symbiotic relationship between corals and zooxanthellae and its impact on coral health and reef ecosystems.
  • The symbiotic relationship between corals and zooxanthellae is vital for coral health, as the algae perform photosynthesis and supply energy to the corals. In return, corals offer nutrients and a protected environment for the zooxanthellae. This interaction not only helps corals thrive in nutrient-poor waters but also enhances reef productivity, contributing to the overall health of marine ecosystems by supporting diverse species reliant on coral reefs.
• Evaluate the effects of climate change on coral reefs, focusing on both biological responses of corals and broader ecological consequences.
  • Climate change poses severe threats to coral reefs through increased sea temperatures leading to coral bleaching and ocean acidification affecting biomineralization processes. As corals expel their symbiotic zooxanthellae during thermal stress, they lose their color and energy source, which can lead to widespread mortality. The decline of coral populations not only disrupts reef structures but also jeopardizes the entire marine food web, impacting fish populations and coastal communities dependent on healthy reef ecosystems for livelihood and protection against erosion.

Related terms

Coral Reefs: Complex underwater ecosystems formed by the accumulation of coral polyps and their calcium carbonate skeletons, providing habitat for numerous marine species.

Zooxanthellae: Symbiotic algae that live within the tissues of corals, providing them with energy through photosynthesis while receiving nutrients and protection in return.

Biomineralization: The process by which living organisms produce minerals to harden or stiffen existing tissues, crucial for the formation of structures like coral skeletons.