Compass Jellyfish by Chandler Reed

Compass Jellyfish

Chrysaora hysoscella

Photo courtesy of (Sabatini, M)

Feeding Habits

The diet of the Compass Jellyfish was recorded during a study in the Walvis Bay Lagoon, which is located in the ocean off of Nambia. This study which was conducted in 2003 recorded a diverse range of food that was consumed by these jellyfish. Some things included dinoflagellates, carideans, and an abundance of both adult and larvae benthic species.(Flynn, et al) They took note of the medusa size, to see if that determined how much the jellyfish would have ate, but they found no correlation to the size of medusae and amount of food eaten. (Flynn, et al) The abundance of benthic species in the diet could have helped explain their presence off of the coast of Nambia. This could help explain why they travel far away from the British Isles, which is where most Compass Jellyfish are found.

Photo courtesy of (GOOGLE)

Development and Reproduction

Compass Jellyfish are both asexual and sexual reproducers. (Compass) The ephyrae are the asexual reproducers while the medusae are the sexual reproducers. In the medusae, sperm is released from the mouth of males. (Giordano K.D) The females absorb the sperm so that fertilization can take place internally. After this occurs the females releases the young, and they go about developing.The breeding season for these jellyfish is typically varies depending on where they are located. The Compass Jellyfish located around the Great Britain have their breeding season during the summer, while the jellyfish around Africa have their breeding season during the early winter. (Fish, and Fish, 1989)

These promiscuous organisms follow a life cycle close to other scyphozoas. Their life starts as planulae that are released from the females, which float freely for a few days. After this they then settle on an abiotic substrate where they become a polyp. This polyp asexually reproduces by releasing immature medusae called ephyrae.(Fish, and Fish, 1989) This typically happens during the summer time. These are released throughout this period, which causes there to be many examples of different organisms at different stages of maturation. Once mature the Compass Jellyfish will start out as a male that participates in sexual reproduction. (Giordano K.D) Later in it's life it will transition into producing female gametes.

FUN FACTS ABOUT DEVELOPMENT

Chrysaora hysoscella in the medusa stage can revert back to it's polyp stage, but once it is fully mature it will not be able revert back into a polyp!!!!!

Toxicity

The Compass Jellyfish was not known to be toxic to humans. This was reinforced by the fact that they are not typically seen by humans. In 1989 a biologist was treating some samples she had taken, and she noticed a rash had where the stingers had touched her skin. This prompted her to conduct a study to find out what levels of toxicity the Compass Jellyfish had. This study consisted of people being touched and not touched it was determined that the jellyfish have toxins in them that irritate the skin when being touched. (Kokelj, et al) Stinging is followed by lesions which disappears after a few hours. There have been very few cases of stings by this species, partly due to it's rarity, but also due to it being commonly mistaken with other jellyfish. (Kokelj, et al)

Behavior

These organisms are sessile and free floating organisms who remain solitary as adults. They can move as medusae by pulsating their bells which propels them in a vertical direction relative to their body. They are constantly swimming as medusae. (Giordano K.D) It has been observed that they can change swimming techniques in response to hunting and number of prey around. (Giordano K.D)

Lifespan

They typical lifespan of a Compass Jellyfish is roughly one year. This is figured because from June to August it is believed that roughly 90-95% of the jellyfish was up to shore dead. (Giordano K.D) It is unproven as to why this happens, but scientists have hypothesized that they die after releasing their gametes. (Fish, and Fish, 1989)

Bibliography

Buecher, E., Sparks, C., Brierley, A., Boyer, H., & Gibbons, M. (n.d.). Biometry and size distribution of Chrysaora hysoscella (Cnidaria, Scyphozoa) and Aequorea aequorea (Cnidaria, Hydrozoa) off Namibia with some notes on their parasite Hyperia medusarum [Abstract]. Journal of Plankton Research. Retrieved November 28, 2017.

Compass jellyfish photos and facts. (n.d.). Retrieved November 28, 2017, from http://www.arkive.org/compass-jellyfish/chrysaora-hysoscella/

Fish, J., S. Fish. 1989. A Student's Guide to the Seashore, 2nd Edition. Cambridge, NY: Cambridge University Press. Accessed March 20, 2012 at http://books.google.com/books?hl=en&lr=&id=1wD21-DC81YC&oi=fnd&pg=PR7&dq=Fish,+J.+D.+and+Fish,+S.+(1989)+A+student%27s+guide+to+the+seashore.+2nd+Edition.+Cambridge+University+press,+Cambridge.#v=onepage&q=Cnidaria&f=false.

Flynn, B., & Gibbons, M. (2010). A note on the diet and feeding of Chrysaora hysoscella in Walvis Bay Lagoon, Namibia, during September 2003. 303-307. Retrieved November 28, 2017.

Giordano, K. D. (n.d.). Chrysaora hysoscella (Compass jellyfish). Retrieved November 28, 2017, from http://animaldiversity.org/accounts/Chrysaora_hysoscella/

Hays, G., T. Doyle, J. Houghton, M. Lilley, J. Metcalf, D. Righton. 2008. Diving behaviour of jellyfish equipped with electronic tags. Journal of Planktonic Research, 30:3: 325-331.

Kokelj, F., Del Negro, P., & Tubaro, A. (n.d.). Dermatotoxicity caused by Chrysaora hysoscella. Presentation of a case [Abstract]. Europe PMC. Retrieved November 28, 2017.

Sabatini, M. (2008, August 05). Retrieved November 28, 2017, from http://www.marlin.ac.uk/species/detail/2020