Anthozoa

Definition

Anthozoa is a class of cnidarians that includes corals and sea anemones, characterized by their polyp form and lack of a medusa stage in their life cycle. These organisms are primarily marine and play a crucial role in marine ecosystems, particularly in the formation of coral reefs, which provide habitat for numerous marine species. Their unique structure, featuring a central mouth surrounded by tentacles, allows them to capture prey effectively and contribute to biodiversity.

5 Must Know Facts For Your Next Test

1. Anthozoans can reproduce both sexually and asexually, allowing for genetic diversity and rapid population increases.
2. Many anthozoans, like corals, have a symbiotic relationship with zooxanthellae, algae that live within their tissues and provide energy through photosynthesis.
3. Anthozoa is divided into two subclasses: Hexacorallia (true corals) and Octocorallia (soft corals), each with distinct characteristics.
4. Coral reefs formed by anthozoans are often referred to as the 'rainforests of the sea' due to their high biodiversity.
5. Anthozoans have complex life cycles where the polyp stage can exist for long periods, with some species capable of creating large colonies that can live for centuries.

Review Questions

• How do anthozoans contribute to the structure and function of marine ecosystems?
  • Anthozoans are essential to marine ecosystems because they form coral reefs, which serve as habitats for thousands of marine species. By providing shelter, breeding grounds, and feeding areas, these reefs support a diverse array of life. Additionally, anthozoans play a role in nutrient cycling within these ecosystems, helping to maintain ecological balance.
• Discuss the significance of symbiotic relationships in anthozoan ecology, particularly focusing on corals.
  • Symbiotic relationships are crucial in anthozoan ecology, especially for corals that host zooxanthellae algae. This relationship allows corals to obtain energy through photosynthesis performed by the algae, which in turn benefits from the nutrients provided by the coral's waste. This mutualism not only helps sustain coral health but also contributes to the productivity and resilience of coral reef ecosystems.
• Evaluate the impact of environmental changes on anthozoan populations and coral reef ecosystems.
  • Environmental changes such as climate change, ocean acidification, and pollution pose significant threats to anthozoan populations and coral reef ecosystems. Increased water temperatures can lead to coral bleaching, where corals expel their symbiotic algae, resulting in reduced energy supply and increased mortality. Additionally, ocean acidification can weaken coral skeletons, impairing growth and structural integrity. These changes can disrupt the entire marine ecosystem dependent on healthy coral reefs, leading to decreased biodiversity and altered community dynamics.

Related terms

Coral Reefs: Underwater structures formed from calcium carbonate secreted by corals, providing critical habitats for diverse marine life.

Cnidocytes: Specialized cells found in cnidarians, including anthozoans, that contain nematocysts used for capturing prey and defense.

Symbiosis: A close relationship between two different organisms, such as the mutualistic association between coral and zooxanthellae algae, which is vital for coral health.