The Beauty of Coral Reefs
A brief introduction to coral reefs and the JWPM collection
Although coral reefs cover less than 0.1% of the earth’s surface, they are the most biodiverse marine ecosystem in the world and are home to many endemic species. The structure and placement of coral reefs can protect coastlines from erosion and large storms, while the many organisms that call coral reefs their home are an important reservoir of knowledge — providing medical researchers with ideas for new medicine.
A corner in the original Joe Webb Peoples museum in Judd hall
At the Joe Webb Peoples Museum, our current coral collection consists of around 250 specimens collected in the 1800s from nearly 20 different localities. These specimens were collected by a variety of interesting characters including George Brown Goode, a former curator of the museum, Charles Wilkes, captain of the United States Exploring Expedition from 1838 to 1842, and Xantus, a famous naturalist. Aside from their beauty, these coral specimens can tell us a lot about ocean and coral reef conditions in the 1800s, helping us better understand our changing ocean environment.
Physiology of Coral
There are approximately 6,000 species of coral, making them the largest class of organisms in the phylum Cnidaria. Coral falls into two general categories, hard corals and soft corals. Hard corals, also known as scleractinians, form skeletons made of calcium carbonate and act as the building blocks of coral reefs.
Coral are made up of hundreds of individual units called polyps. On the most basic level, polyps have a sack-like body with a singular opening, called the mouth, which works to intake nutrients and expel waste. This opening leads to a digestive cavity where food is sent after being trapped by tentacles that surround the mouth. These tentacles contain stinging cells, a characteristic that defines members of the phylum Cnidaria. These tentacles help the coral capture and ingest plankton for food, clear away debris from the mouth, and act as the animal’s primary means of defense. Polyps are made up of two specialized layers of cells with a flexible jelly-like skeleton called mesoglea in between. The outer layer, called the ectoderm, surrounds the polyp’s sack-like body and is responsible for building a calcium carbonate exoskeleton in hard coral. The inner layer, called the endoderm, is responsible for digesting food brought into the digestive cavity.
Symbiotic Relationship With Zooxanthellae
Many coral species have a symbiotic relationship with algae called zooxanthellae. The presence of zooxanthellae is what gives coral their distinct color. However, there is more to their symbiotic relationship than just aesthetics. The coral provides the environment and resources needed for zooxanthellae to photosynthesize, and in return, the coral receives the byproducts of photosynthesis to use for energy. These waste products are necessary nutrients for coral survival, implicating zooxanthellae as a key factor of coral health.
Coral bleaching happens when zooxanthellae are expelled by the host coral as a response to stress. Without zooxanthellae, coral are not able to receive the nutrients they need in order to survive, resulting in coral death. In effect, coral bleaching can lead to coral death.
Coral stress and subsequent bleaching can be caused by a range of environmental factors, including changes in pH and temperature. This makes them particularly susceptible to climate change as ocean temperatures rise and ocean waters become more acidic.
Types of Reefs
Reef formation depends on the material of the surface to which reef building corals bind, light levels, salinity, and suitable temperature conditions. When reef building coral larvae enter an environment where all these conditions are met, a coral reef is formed.
There are 3 types of coral reefs
Fringing reefs are the most common type of reef. They grow directly from the shore along the edge of a continent or island.
Barrier reefs run parallel to the shoreline and are oftentimes separated from the mainland by a lagoon. These reefs are usually not found in a continuous loop. The largest example of a barrier reef is the 1200 mile long Great Barrier Reef off the coast of Australia.
An Atoll reef is a ring shaped reef that surrounds a lagoon. Atoll reefs typically form away from land, as they usually grow with assistance from a submerged island or a volcanic cone.
How do corals spawn?
Coral can reproduce in one of two ways. When corals asexually reproduce, a polyp breaks off from the main colony and starts forming its own colony. Corals sexually reproduce in broadcast spawning events. During a broadcast spawning event, multiple coral release eggs and sperm into the water column at the same time. These eggs and sperm then join to create free floating larvae called planulae. The planulae then swim, anchor themselves, and begin building their skeleton.
Corals under climate change
Due to pollution caused by humans, sights like the one on the right are becoming more and more common. Coral reefs, some of the most diverse ocean ecosystems, are particularly sensitive to climate change stressors due to their susceptibility to changes in temperature and acidity. Without direct action to mitigate the impacts of climate change, we can expect to see a continued increase in coral bleaching events.
Joe Webb Peoples Museum
In the 1800s naturalists pioneering the frontier of the natural world did so by collecting and preserving flora and fauna they found in the field. These specimens were then jarred, dried, or taxidermied and sent either to private collectors to be stored in personal cabinets of curiosities, or sent to institutions such as museums or universities. These institutions also sponsored individuals and expeditions in the hopes of collecting and identifying new species, as well as bolstering their collections.
Cabinet of curiosities
Similarly, the recent coral collection at the Joe Webb People’s museum was collected by naturalists along with explorers who by chance collected coral on their expeditions and wanted to donate it to the museum.
Current Coral Collection
Thanks to the scanning efforts of museum workers, we have some of the coral specimens in our collection 3D scanned so that they can be observed digitally. Visit the linked website to view other 3D coral scans.
3D model - JWP_Acropora_Recent - 21944
Due to the wide range of collection events, the current coral collection showcases an array of coral from many localities.
The map on the left highlights areas coral reefs are generally found, while the map on the right has markers for each locality from which coral in our collection was collected.
Craft Sea Critters
Recently the Joe Webb Peoples Museum has started a new project titled Craft Sea Critter. Join us in creating a Wesleyan community built crafted ocean ecosystem! Learn how to crochet sea creatures at one of our events or make one following your own design and drop it off at one of our drop boxes. The main animals building reefs in the modern world are corals, but we welcome other reef builders and dwellers, including sponges, clams, fish, sea-slugs, turtles, octopus, sharks and whatever else you can think of! Not only will our ecosystem be home to modern day ocean critters - extinct animals like ammonites, ichthyosaurs, and mosasaurs are welcome as well! Crocheted, knitted, embroidered, 3D-printed, no matter the medium all contributions to our ocean reef are welcome. Check out our website for more information about the project and learn how to get involved:
