Title. Euphausia superba. Author. Sophia Erb

Transcription

1 Title Using geometric probability to compare the random and actual mating success of Atlantic Krill, Euphausia superba Author Sophia Erb

2 Abstract Currently the most abundant species on Earth, Atlantic krill, or Euphausia superba, are an extremely important factor in food chains across the world and play an important role in the environment of the ocean (Euphausia superba). Atlantic krill are sexually reproducing organisms that have certain restrictions to their mating behavior. Due to their small structure and clear, translucent bodies, biologists seeking to study these organisms may find it difficult to catch them and therefore study them. However, much information has been collected on Atlantic krill, especially their mating process.

3 Introduction The Euphausia superba, more commonly known as the Atlantic krill, live in oceans around the world. Regardless of its small stature which is only about two inches (five centimeters) in length it plays an important role in the world s food chain (Krill Euphausiacea). Without these small organisms, food chains would collapse. Krill are invertebrates that are eaten by birds, fish, and whales. If not eaten, krill can live an incredibly long time and mate more than once. Their ten year life span allows them to reproduce and keep the food webs they influence intact. Krill are sexually mature by age 3, and tend to reproduce rapidly. Considering krill are at the bottom of the food chain, they are herbivores and do not swim alone. Sometimes krill congregate in swarms so dense they can be seen from space (Krill Euphausiacea). These fascinating organisms allow life on Earth to flourish; without the Atlantic krill, life as we know it may not even exist. Method In order for Atlantic krill to maintain their huge population, mating must occur. Female krill do not choose which male they want to mate with; instead, whichever male is stronger and more persistent will be able to mate with his desired female. The mating is a short procedure; [t]he whole mating ritual only last[s] 12 seconds with five distinct phases ( Secret sex life of Antarctic krill revealed for the first time ). The first step, chase, is when the males pursue a single female. Once the most persistent, dominant male gets to the female, he probes her, which is the second step. The third step, known as embrace, allows the male to actually start the mating session, which then quickly moves to the fourth and fifth steps, flex and push ( Secret sex life of Antarctic krill revealed for the first time ). The male krill releases sperm sacs which then fertilize the female krill s eggs.

4 Atlantic krill will not start their mating in the shallow waters. These marine zooplankton crustaceans will go down into the cold waters of the ocean, down to 507 meters or even deeper. Here, the five steps will take place when two males spin and twirl with one female, trying to be the successful father. Considering the whole mating session takes only 12 seconds, the spawning process is quite long. It can last up to five months, yet the krill must wait until they are sexually mature at around three years old. Figure 1: This image of an Atlantic krill was obtained from Google images. The rectangle surrounding the krill represents the surface area of the female krill as the male would see her. The circle on the female krill represents her vaginal opening.

5 Results The random probability of mating success in the Atlantic krill is 1.11%. Krill are extremely abundant for such a low success rate; their abundance is due to their long life span and ability to mate more than once. Calculations are shown below: Rectangle Area: l h 5.7cm 1.5cm = 8.55cm 2 Circle Area: r cm (.175cm) 2 = cm 2 Σ All shapes: 8.55cm cm 2 = cm 2 Target area: / = Percent: = 1.11% Discussion The Euphausia superba, more commonly known as the Atlantic krill, has an overall mating success rate of an Atlantic krill is 1.11%. The krill is a sexually reproducing organism needing both male and female reproductive parts. Atlantic krill take only twelve seconds to reproduce, using five different steps for successful mating: chase, probe, embrace, flex, and push. In order for these marine organisms to reproduce, they must be sexually mature by three years old and go down to about 500 meters or deeper in the Atlantic Ocean. All Atlantic krill can live up to ten years old and grow by feeding on plants. The abundance of krill does not fluctuate very much due to the quick reproductive rate and how quickly the krill get hunted. The sperm sacs fertilize the eggs from the female and can produce many offspring from one single mating session. Atlantic krill have a 1.11% success rate of mating, and can produce multiple offspring in one mating session.

6 References Encyclopedia of Life. (n.d.). Euphausia superba Krill. Retrieved October 2, 2013 from National Geographic. (n.d.). Krill Euphausiacea. Retrieved October 2, 2013 from Pollock, K. (2011). Secret sex life of Antarctic krill revealed for the first time. Retrieved October 2, 2013 from Digital Journal Reports Web site