Life Cycle edit
The Atlantic Sea Nettle will go through physical form changes typical of other jellyfish. The Atlantic Sea Nettle matures in a stationary polyp stage, either in a reproductive form or a feeding form. The reproductive polyp form will bud from the stalk through asexual means, grow, and form into a medusa, the mobile form seen in ocean and sea waters. [1]
The polyp form of the Atlantic Sea Nettle is capable of thriving in low oxygen concentrations. In severe hypoxic conditions, typical of seasonal changes in the Chesapeake, the polyps have been shown in experimental conditions to thrive for approximately up to 5 days, whereafter they will eventually die off. During the summer months in the Chesapeake Bay, oxygen concentrations become reduced at greater depths, due to changes in weather patterns, where polyps normally occur. The polyps survival in low oxygen environments may be attributed to highly developed mechanisms for removal of oxygen, ability to reduce metabolic rates, and ability to utilize anaerobic respiration. [2]
The Atlantic Sea Nettle species is highly responsive to the seasonal changes of sea water. Population sizes have been shown to increase and decrease in response to changes in water temperature. In the Gulf of Mexico, the medusae are more common and will proliferate during the warmer, summer months of June to July. As ocean and sea waters cool, medusae's ability to pulse becomes reduced and will sink to lower depths of the ocean. The predatorial capabilities of the medusae become reduced. Water temperatures of approximately 15°C have been shown to be the temperature limit prior to medusae death. [3]
Niche edit
The bloom of life and seasonal death of sea nettle during their lifespan contribute to carbon recycling in seas. The Atlantic Sea Nettle plays a major role in the nutrient abundance of the Chesapeake Bay. As water temperatures cool and medusae sink to the bottom of the sea, the dead medusae contribute large amounts of biomass, which are decomposed by bacteria. After decomposition in the oceans floor via bacterium, the marine nutrients necessary for other aquatic life dramatically increase. [3]
The Atlantic Sea Nettle's main predation of ctenophores, other jellyfish-like organisms, allows for the abundance of copepods. The copepods are a main food source for commonly consumed fish and shellfish in the Chesapeake Bay. The Chesapeake Bay food web may heavily rely on the Atlantic Sea Nettle, making the species a keystone species. [4]
Stinging Mechanism edit
Nematocysts organelles within cnidocytes synthesize and transfer the venom into stings. The venom of the Atlantic Sea Nettle acts on the tissues of smaller prey, particularly blood and nervous tissue. In vivo studies show the venom causes paralysis of tissue immediately after a sting. The fins of zebrafish injected with venom caused abnormal swimming patterns. Hemorrhage of the eyes in zebrafish also occurred, indicating effects on blood tissue circulation. Kidney and liver damage following venomous injection have been shown in smaller fish. [5]
References edit
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- ^ Freeman, Scott (2014). Biological Science. Pearson. pp. 653–654. ISBN 0321743679.
- ^ Condon, R. H., Decker, M. B., & Purcell, J. E. (2001). Effects of low dissolved oxygen on survival and asexual reproduction of scyphozoan polyps (chrysaora quinquecirrha). Hydrobiologia, 451(1-3), 89-95. doi:http://dx.doi.org.montgomerycollege.idm.oclc.org/10.1023/A:1011892107211
- ^ a b Sexton, Margaret A.; Hood, Raleigh R.; Sarkodee-adoo, Judith; Liss, Amanda M. "Response of Chrysaora quinquecirrha medusae to low temperature". Hydrobiologia. 645 (1): 125–133. doi:10.1007/s10750-010-0222-y.
- ^ "Chrysaora quinquecirrha (Sea nettle)". Animal Diversity Web. Retrieved 2016-11-02.
- ^ Ponce, Dalia (2015). "Comparative study of the toxic effects of Chrysaora quinquecirrha (Cnidaria: Scyphozoa) and Chironex fleckeri (Cnidaria: Cubozoa) venoms using cell-based assays". Toxicon. 106: 57–67 – via Elsevier Science Direct.