CoralPolyps
Coral Polyps
Corals belong to the hpylum Cnidaria and class Anthozoa. Corals exist as individual polyps or in colonies.[1].
- talk about what a Polyp is and where they are found [2]
Anatomy
Coral polyps are multicellular organisms with limited organ development. The average polyp grows to 1-3mm in diameter and can exist as a solitary individual or as a group of interconnected polyps called a colony. Colonial polyps are connected by the coenosarc, allowing polyps to communicate and share nutrients. Similar to cnidarians, polyps contain three body tissues: epidermis, mesoglea, and gastrodermis. Corals are categorized as scleractinian, or hard corals, or Alcyonacea, or soft corals depending on whether or not they produce a calcium carbonate skeleton.[1]
Corals that create a rigid calcium carbonate skeleton are the hard corals. These are the primary corals involved in reef building and are termed hermatypic. Typically, scleractinian coral polyps are characterized as having sets of six tentacles, septa, and mesenteries. The tentacles encircle the mouth and are used in defense and the capturing of prey.[1] They contain stinging cells called nematocysts. These poison-injecting are used to incapacitate small prey, as well as deterring predators.[3] The mouth is the only opening to the gastrovacular cavity and is used to ingest food and expel waste. The gastovascular cavity contains mesenteries, which internal folds that increase the surface area of the stomach. Mesenteries are known to contain digestive filaments that aid in food capture. The mesenteries are supported by septa.[1]
Hard coral polyps attach to the substrate via the calyx and basal plate. Calcium carbonate is secreted at the base of the animal.[3] As polyps die, they leave the secreted calcium carbonate skeleton behind. In living scleractinian coral colonies new polyps will grow in place of the dead polyp. The build up of calcium carbonate over time leads to the formation of coral reefs.[1]
Soft coral polyps are similar in structure to those of hard corals. However, ahermatypic corals do not have calyx, septae, or basal plates and do not secrete calcium carbonate. The polyps are also characterized as having tentacles and mesenteries grouped into sets of eight. These corals are often specialized for filter feeding.[1]
- Describe the different parts that make up the Polyp and what they do. (Tentacle, mouth, basal plate, etc.)[4]
- Explain how nerve cells loosely connect Polyps to one another creating a nerve net between a colony of Polyps
Symbiotic relationship with zooxanthellae
- Define symbiosis.
Symbiosis can be defined as any of several living arrangements between members of two different species. Symbiotic relationships can be categorized into three different types including, mutualism, commensalism, and parasitism. The species involved in these relationships are called symbionts.
In a mutualistic symbiotic relationship both species involved benefit. An example of this type of relationship is the one between oxpecker birds and rhinos. An oxpecker birds will land on the back of a rhino and eat the ticks, fleas, and other parasites that live on them. Both symbionts benefit. As the oxpecker receives nutrients from eating the parasites the rhinos are getting rid of the parasites feeding on them. In many cases the mutualistic symbiotic relationship is obligative meaning that both symbionts rely on the benefits gained so much that without them neither symbiont would survive.[5].
In commensalism one symbiont, called the commensal, benefits from the relationship while the other symbiont, called the host, remains unaffected. An example of this type of relationship could be when smaller fish follow bigger fish in order to eat leftover food. The smaller fish benefit by gaining nutrients from the leftover food while the bigger fish are unaffected as they are already done with the food.[6].
Parasitism is a non-mutual symbiotic relationship between species where one species, the parasite, benefits at the expense of the other, the host. A classic example of this type of relationship is when a tapeworm attaches itself to the insides of the intestines of other animals and feed on the food that the animal ingests. The parasite benefits by gaining nutrients, but does so at the expense of the host because it now needs to eat more in order to survive.[7].
- Explain how Polyps and Zooxanthellae have a symbiotic relationship. (what each does for each other)[1]
Zooxanthellae are photosynthetic algae that live inside coral polyps. Coral Polyps and Zooxanthellae have a mutalistic symbiotic relationship. The calcium carbonate skeleton produced by the coral polyps provide the Zooxanthellae with a protected environment suitable for photosynthesis due to the shallow environment with which many coral live. In return, the photosynthetic algae produce oxygen and aid the coral in removing waste. Additionally, Zooxanthellae provide the coral with nutrients such as glucose, glyserol, and amino acids, which are products of photosynthesis. These compounds are utilized by the coral as building blocks in the manufacture of fats, as well as the synthesis of their calcium carbonate skeleton.
Some polyps are able to capture enough nutrients to survive without Zooxanthellae, but this is rare. It has been found that Zooxanthellae donate up to ninety percent of the organic material produced during photosynthesis to the host coral tissue. Therefore, the relationship between polyps and Zooxanthellae is obligative in most cases.
The coral, produced by the Polyp, provides the algae with a protected environment and the compounds necessary for photosynthesis, which are metabolic waste products of the coral. In return, the algae produce oxygen and help the coral to remove wastes. Most importantly, they supply the coral with organic products of photosynthesis which are predominantly carbohydrates. These compounds are utilized by the coral as building blocks in the manufacture of fats, as well as the synthesis of their calcium carbonate (CaCO3) skeletons. Zooxanthellae often are critical elements in the continuing health of reef-building corals. As much as 90 percent of the organic material they manufacture photosynthetically is transferred to the host coral tissue.
- Explain how through this relationship both are mutually benefited.
- Explain how the relationship is also obligative. Meaning that, in most cases, neither can live without the other.
Stony Coral and Soft Coral Coral
- Stony corals make a calcium carbonate skeleton, soft corals do not do this
Feeding
- How Polyps are able to use their tentacles to pull in zooplankton and small fish to their mouths
Reproduction
- Explain the process of reproduction
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 NOAA, NOAA Coral Reef Conservation Program Coral 101. NOAA. Web. 5 Mar 2014. <http://coralreef.noaa.gov/aboutcorals/coral101/>.
- ↑ Gray, Susan Heinrichs. Coral Reefs. Minneapolis, Minn: Compass Point Books, 2000. eBook Collection (EBSCOhost). Web. 22 Feb. 2014.
- ↑ 3.0 3.1 Cite error: Invalid
<ref>tag; no text was provided for refs namedPechenik - ↑ Pechenik, J. A. . Biology of the invertebrates. sixth. McGraw-Hill, 2010. print.
- ↑ "Mutualism(biology)." . Wikipedia, 14 Mar 2014. Web. 1 Apr 2014. <http://en.wikipedia.org/wiki/Mutualism_(biology)>.
- ↑ "Commensalism." . Wikipedia, 25 Mar 2014. Web. 1 Apr 2014. <http://en.wikipedia.org/wiki/Commensalism>.
- ↑ "Parasitism." . Wikipedia, 26 Mar 2014. Web. 1 Apr 2014. <http://en.wikipedia.org/wiki/Parasitism>.