Corals References [1] International Coral Reef Initiative. What are corals? https://icriforum.org/about - coral - reefs/what - are - corals / [2] The Editors of Encyclopaedia Britannica. Coral https://www.britannica.com/animal/ coral [3] Walter M. Goldberg (2018). Coral Food, Feeding, Nutrition, and Secretion: A Review https://doi.org/ 10.1007/978 - 3 - 319 - 92486 - 1_18 [4] Charles Birkeland (1997). Life and Death of Coral Reefs PMID 30100341 [5] Vishal Thakur (2022). How Do Coral Reefs Form? https://www.scienceabc.com/nature/how - do - coral - reefs - form. html [6] National Oceanic and Atmospheric Administration. Coral Facts https://coralreef.noaa.gov/education / [7] National Oceanic and Atmospheric Administration . Coral reef ecosystem https://www.noaa.gov/education/resource - collections/marine - life/ coral - reef - ecosystems [8] Figure 2: https://en.m.wikipedia.org/wiki/The_Structure_and_Distribution_of_Coral_Reefs#/media/File:Atoll_forming. jpg David Cathomas , Bündner Kantonschule , Class 6Gh Coral Biology Corals are invertebrate animals and belong to the group of Cnidaria. Other animals of this group are jelly fish and anemones. They share the same characteristics; a stomach with a mouth surrounded by stinging tentacles. Each individual coral animal is called a polyp. These polyps mostly are in colonies [1]. The tentacles of a coral, which gather food, are extensible and are armed with nematocysts which stings and paralyzes their prey [2]. Some corals can feed on plankton and planktonic algae [3]. Others can live from products of their zooxanthellae which are photosynthetic organisms that contain chlorophyll. The zooxanthellae provide the coral with their colors [4]. Corals can reproduce sexually and asexually since they either can be male or female or both simultaneously. Their asexual reproduction is a result of cloning called budding where the polyp matures and divides creating a identical polyp. There is also fragmentation, where the entire colony divides and creates new, separate colonies. Sexual reproduction includes eggs getting fertilized. They then can settle themselves on a substrate and become a polyp and become a new colony. Sexual reproduction can occure between different colonies which leads to greater diversity [5]. Coral R eef E cology Hard corals are the main reef - building corals while the soft coral are present they do not form reefs [6]. Coral reefs are the most diverse ecosystem in the world. A quarter of the ocean’s fish depend on healthy coral reefs. Coral reefs are used by fish and other organisms as shelter, to find food and to reproduce. The coral reef also protects the coastlines from storms and erosion. Because of the climate change and pollution the coral reef ecosystem is severely threatened [7]. Atolls • Fringing reefs lie near emergent lands. They are recently formed and shallow. • Barrier reefs lie farther away from the coast and are broader. They are separated from the coast and can have emerging reef parts. • Atolls lie of the coast and are ring - shaped reefs with a lagoon in their middle. Atolls have emerging reef parts. [1] There are hard and soft corals. Hard corals produce a calcium carbonate skeleton whereas soft corals don’t have a skeleton [6]. Figure 1: Anatomy of a Coral polyp [2] Figure 2: [8]