Anthozoa Life Cycle
If you've ever bought a coral necklace, surfed a reef break or stuck your finger in an anemone, you might be familiar with the class Anthozoa, which includes corals, sea anemones, sea fans, sea pens and sea pansies. Anthozoans' life cycle is limited to two phases. However, as simple as their life might appear, many marine organisms depend on Anthozoans for their survival.
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Sexes
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To fully understand the life cycle of an Anthozoan, it is critical to understand their sexes and reproductive practices. Anthozoans, a class under the phylum Cnidaria, are both sexual and asexual. Sexual reproduction takes place when a sperm and egg are united from two unique parents, while asexual reproduction occurs when an Anthozoan splits to form two new individuals.
Larva
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Once Anthrozoan eggs are fertilized, either outside or inside the parent organism, the result is a new individual in the larva phase. A larva can live in open water for days or even weeks and does not always necessitate feeding. A larva quickly becomes a polyp, and remains in that phase for the rest of its life.
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Polyps
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The polyp phase is also the final phase of an Anthozoan life. Anthozoans do not reach the medeusa phase that other Cnidarians do. Anthozoan polyps often have a flower-like appearance and wide gastrovascular cavity, which serves as both a mouth and anus. According to the Encyclopedia of Life, Anthozoans in the polyp phase of life are often brightly colored.
Sea anemones are carnivorous and tend to live in warm water. Their long tentacles are capable of catching fish with the use of nematocysts. Sea anemones also have symbiotic relationships with other fish, meaning that the fish and anemone live together in a harmonious and mutually-beneficial relationship.
Sea coral polyps often break apart and form new polyps. Coral reefs are large structures created from generations of polyps. Thousands of species of marine life live in or depend on coral reef for survival.
Reproduction
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Different species of Anthozoans are either separate sexes or both sexes within the same organism. Sex organs are highly undefined within anemones and corals. Eggs and sperm are either released through the mouth for outside fertilization, or fertilized internally and released as embryos in asexual Anthozoans.
According to the TreeofLife.org, Anthozoan reproduction can take place by means of cloning. Fragmentation occurs when a piece of the Anthozoan body breaks off and forms a new individual.
Sexual reproduction among Anthozoans either takes place outside or within the parents' body. Eggs and sperm are released through the gastrovascular cavity for fertilization outside the body. Alternately, a species with both sexes can fertilize eggs within its body and release embryos which soon become larvae.
Threats to Life Cycle
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The life cycles of Anthozoans are responsible for the massive coral reefs throughout the world. Anthozoans also lend support, food and shelter to thousands of marine species. According to Coral.org, fishing, construction and pollution have both threatened and damaged coral reefs. Additionally, the threat of global warming and rising water levels threaten the Anthozoan life even further.
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References
- Photo Credit coral image by DOLPHIN from Fotolia.com
