Coral reefs are complex marine structures that offer shelter to thousands of different marine animals, while also serving as natural resources. Unfortunately, however, coral reefs can sometimes be fragile ecosystems that must be managed.
Coral reefs may seem like intriguing rocks, but they’re actually invertebrates belonging to the Cnidaria phylum–the same category as jellyfish and sea anemones. Read on to discover six interesting facts about our most diverse and valuable reef system!
1. They’re Animals
Coral reefs are colorful rocky structures that may resemble plants or rocks; but in reality are comprised of marine invertebrates from the Cnidaria phylum – such as jellyfish and sea anemones. Their hard structures consist of external limestone skeletons formed by polyps (soft-bodied animals). Working together, coral reefs create large reefs known as coral atolls.
Polyps extract calcium from ocean water to form a solution which then hardens around their soft bodies, providing coral with its rock-like appearance and acting as the basis for an entire reef system.
Adult coral are sessile organisms that cling to the bottom of the ocean floor, making them inactive. But their larval or baby life stages, known as coral larvae, can swim! When coral reproduces, both sperm and eggs are released into the water and fertilized to form these tiny baby-swimming larvae which will then develop into full colonies as time progresses.
Coral reef environments attract an abundance of plants and animals, such as fish, shrimp, crabs, clams snails squid and sea urchins – providing essential protection to many young fish species. Coral also serves as protective homes for some marine organisms that depend on them as protective environments.
2. They’re Not Plants
Coral reefs are among the world’s most complex ecosystems, yet are frequently misunderstood. Contrary to popular belief, corals are not plants but rather animals belonging to the Cnidaria group that also includes jellyfish and sea anemones. Corals form colonies by growing together forming large colonies; our Great Barrier Reef contains approximately 600 different species.
Coral reefs derive their vibrant colors from zooxanthellae algae that lives within them, providing food and shelter in exchange for oxygen, carbon dioxide and nutrients from the water. Furthermore, these alga help build hard base skeletons which give reefs their distinctive appearance and structure.
Corals may look like colorful marine plants or rocks, but according to the National Oceanic and Atmospheric Administration they meet all five criteria that define animals: multicellularity, feeding on other organisms for sustenance, internal digestion systems and embryonic development are all hallmarks of life for an organism; corals also move independently while possessing the capability of stinging their enemies when necessary.
3. They’re Adaptive
Coral reefs have long been considered “the rainforests of the sea”, providing shelter, food and water to thousands of marine organisms and protecting shorelines against erosion and rough waves.
Coral might look like rocks, but these invertebrates belong to the Cnidaria phylum and belong to sea anemones and jellyfish as distant relatives. Their polyps grow together into colonies that act like one organism; coral reproduction may occur either asexually or sexually and they can either eject their mouths with algae for feeding purposes, or host zooxanthellae that take in carbon dioxide and produce sugars, oxygen and return nutrients back into their respective coral colonies for feeding purposes.
Corals are highly adaptive animals, capable of adapting to an array of conditions from water temperature and sunlight levels, as well as changing shape to adapt to specific environments. Some coral species have even adjusted to warmer temperatures by releasing algae or altering genetics; camouflaging themselves by blending with their surroundings can help protect from predators as they hunt for sustenance; tentacles equipped with stinging cells can grab zooplankton while also acting as defense mechanisms against potential threats.
4. They’re a Key Resource
Coral reefs are among our planet’s most precious natural resources, providing more than beauty and recreation to millions of people across the world. Not only are coral reefs beautiful, they protect coastal communities against storms and tsunamis, provide fisheries with crucial habitat, and aid our understanding of ocean ecosystems.
Though corals resemble plants, they are invertebrates (animals without backbones). Corals belong to the Cnidaria class of invertebrates which also includes jellyfish and sea anemones. Coral colonies consist of genetically identical polyps with tentacles designed to catch, debilitate and consume small floating plants or animals that come within range. Their brilliant colors come from tiny algae living inside called Zooxanthellae that capture sunlight for energy production while giving back food, oxygen as well as helping create its hard protective skeleton.
Coral reefs can last hundreds or even thousands of years and serve as indicators of environmental conditions, providing vital insights into ocean history. Corals also symbolize marine biodiversity and are held dear by many cultures worldwide as symbols of wealth, good luck and fertility.
5. They’re a Living Ecosystem
Coral reefs are natural structures composed of calcium carbonate skeletons laid down by corals – small marine animals closely related to jellyfish that form these spectacular structures. Coral reefs support an incredibly vibrant and diverse ecosystem which provides shelter, food and protection to many marine animals.
Stony corals such as gorgonia, fire coral, and brain coral use ions in the water to form calcium carbonate exoskeletons for themselves and their photosynthetic partners (zooxanthellae). Other reef-building corals include acropora, elkhorn and foliose corals that use sand, rubble or sediment as skeleton materials while others utilize flexible materials like mollusk shells or rubbery polyps.
Corals are animals that usually exist as individual organisms; however, colonies of them often form groups, called colonies. A colony can range in size from a single mound or entire reefs; typically formed by genetically identical coral animals known as polyps which grow together through a process called budding.
Corals are nocturnal animals; during the day they retreat into their skeletons for shelter before spreading out their tentacles at night to feed on plankton. Furthermore, corals contain stinging cells (cnidocytes) which allow them to defend against predators as well as each other.
6. They’re a Keystone
Coral are considered keystone species by ecologists. This means that they have a significant effect on their ecosystems, and without them the ecosystem would change dramatically. Sharks serve as keystone predators in Caribbean reef ecosystems by keeping herbivorous fish below in the food chain from becoming too numerous and overrunning the coral population and damaging it permanently – their jaws help graze on algae that would otherwise overtake and destroy it, thus keeping this vital ecosystem healthy and vibrant.
Coral reefs provide many nooks and crannies where species such as parrotfish, sea turtles, crustaceans, stingrays, and zooplankton can hide from predators; making it essential habitat for them and others who depend on these reefs for survival.
Unfortunately, corals face many threats. Sometimes this means physical damage from boats hitting them or accidentally dropping anchors onto them; but pollution often has more devastating effects, causing coral to bleach (turn white), stop growing, or even die out altogether due to factors such as industrial runoff that raises water toxicity levels and greenhouse gases generated from human activity that alter temperature of their environment. That is why Defenders of Wildlife encourage you to support our efforts and donate today.
7. They’re a Keystone in Managing Carbon Dioxide Levels
Coral reefs are among the world’s most biodiverse ecosystems, providing shelter to fish, birds and other creatures – often boasting more species in a 2-acre coral reef area than there are bird species across North America!
Coral reefs usually get their vibrant hues from symbiotic algae called zooxanthellae that live inside each polyp. These microscopic organisms produce carbon dioxide, water, oxygen, glycerol and amino acids in exchange for food; in turn they sift through seafloor mud to extract inorganic mineral skeletons necessary to the creation of corals.
corals have the ability to reproduce both sexually and asexually through photosynthesis, while also breaking apart into fragments which reattach themselves back onto the ocean floor, creating new colonies. Corals are famous for their resistance to extreme temperatures and infections – thanks to natural selection over millions of years – as well as fighting deadly pathogens like Thalassomonas Loyola bacteria which threaten them microbially.
Scientists can accurately ascertain how long a coral has existed by cross-sectioning its hard, calcium carbonate skeleton. Like tree rings, its bands record changes in temperature and water chemistry over time. Furthermore, scientists can use carbon dioxide levels in the atmosphere as another marker to ascertain whether coral reefs have been exposed to rising levels that reduces their ability to form new skeletons due to slow aragonite production rates that make formation of their hard structures harder for reefs to maintain themselves.