Corals | Anthozoa
Corals | Anthozoa
Corals, belonging to the class Anthozoa, are marine invertebrates that typically live in compact colonies of many identical individual polyps. They are most commonly found in warm, shallow waters where they form coral reefs, the largest living structures on Earth, through the secretion of calcium carbonate. Existing for around 500 million years, corals have evolved into a diverse range of species. These creatures play a crucial role in their ecosystems, providing habitat and protection for a vast array of marine life. Corals also have a symbiotic relationship with zooxanthellae algae, which provide them with nutrients through photosynthesis.
Corals are unique marine organisms composed of many small creatures called polyps, which cluster together to form coral colonies. Each polyp has a simple, sac-like body with a single opening surrounded by tentacles. They use these tentacles to capture tiny organisms for food. Corals are mostly stationary, anchored to the ocean floor, but some can retract their polyps for protection. They lack conventional senses like sight or hearing, instead relying on water currents and chemical signals in their environment. Internally, they have a simple digestive system and, interestingly, corals don't have a brain but a simple nerve net for basic reflexes.
The symbiosis between humans and corals is profound, rooted in our reliance on coral reefs for food, coastal protection, and income through tourism and fishing. Historically, indigenous cultures revered corals for their beauty and utility, using them in jewelry and medicine. In popular culture, corals often symbolize diverse marine life, featured in films like "Finding Nemo."
Unfortunately, human activities like overfishing, pollution, and climate change threaten coral reefs globally. In response, conservation efforts have intensified, with initiatives focusing on marine protected areas, coral farming, and restoration projects to safeguard these underwater treasures for future generations.
Most corals have a symbiotic relationship with algae living in their tissues. These algae provide them with the right nourishment or energy that they generate from the sun. Still, others feed on small fish, plankton, and even cetaceans by stinging and capturing them with their long tentacles. Most corals feed at night.
Anthozoa can reproduce sexually or asexually. Asexual reproduction can be transverse, pedal laceration, longitudinal fission, or autotomy of tentacles. Members of this group release sperm and eggs into the water. When the egg is fertilized, it transforms into a larva, and then the last stage, which is polyps.
Anthozoa has soft body tissues. To protect these soft tissues, it secretes a hard and tall nonliving substance. Algae love this substance as it offers them protection and components for photosynthesis. The algae are what gives the Anthozoa its color, which can be pink, yellow, red, and many more.