[TOEFL소모임] 1월 18일 Topic

사정상 이번에만 이렇게 합니다. 이거 치는데 20분 -_-;;; 빡세다!   <A name="[문서의 처음]"></A> Bluegills Anglers will recognize the bluegill as one of the most popular gaming fish in North America and it is frequently found in freshwater lakes and ponds. This relatively small fish which rarely reaches length over 6-9 inches (15-23cm) has also been the subject of intense study by many wildlife biologists for its unusual mating habits. While similar to other fish in that the male cares for the offspring, the alpha males which are larger than the females and other males can never be sure that it is truly their own fry which they are rasing since there are others which try to circumvent the mating rituals and fertilize the eggs by deception. Comprising roughly 80% of the breeding population, large parental males, distinguished by their size, copper colored bars across the top of their heads behind the eyes, and silvery blue breasts that may turn yellow or orange during the spawning season, commonly manage bluegill reproduction. they do not reach sexual maturity until their third or fourth year and this delay allows them to direct their consumed food resources to developing a large body mass, which is advantageous for successfully defending their territory and fighting off predators. Because these fish are colony spawners, adult parental males will excavate plate-sized nests in groups of 20 or 30, called 'beddings', by sweeping their tail fins across the sandy floor to make depressions. Then, in the shallow water, the male circles the nest and makes grunting noises to attract one or more females. The male guards the newly deposited and fertilized eggs and continues to do so even after the hatch and the emergence of the fry until they are old enough to survive on their own. A small proportion - about 20% - of bluegill males do not wait until they are large enough to defend territory before entering the reproductive process. Cuckolds, or sneakers, divert most of their energy towards their gonads that produce milt, a secretion from their testes containing spermatozoa; as a result, they have invested in a procreative strategy requiring them to take advantage of nearby nests. Cuckholds are too meek to successfully attract a female fish on their own. They seek out a large parental male, hide in the weeds adjacent to the parental male's breeding grounds, and wait for a school of female fish to pass over. Once a female chooses a partner, she will tilt her body and release roughly 30eggs in a motion referred to as a 'dip'. Normally, the resident parental male would shower theses eggs with his own milt, but before he has a chance to reach all of them, the diminutive cuckold will leave his safety zone and dart into the dangerous nest area to squirt his own milt toward the eggs, quickly returning to his point of origin without being caught. With this tactic, he hopes to fertilize as many of the eggs as possible before they settle into the hole, and will use his undersized body to advance with utmost agility. If fortunate enough to complete the task without encountering any significant harm, the cuckold will go on to stalk other parental male nests over the same season. The rapid dashing technique is limited to only two seasons since his physical maturation, while delayed, cannot be halted resulting in a larger body with less agility and so as to increase the likelihood of passing his genes onto the next generation, he develops a new method of mimicry to achieve his goal. An adult cuckold bluegill is still not as beefy as a parental male and can easily be mistaken for a female of the species. As he ages, the cuckold will acquire similar markings, which completely disguise him from parental males and allow him to easily slip into schools of female fish unnoticed. In this fashion, he will travel around the warm waters until a nearby female decides to spurt her eggs downward toward an established nest. The cuckold swoops down, maneuvers fairly close to the fallen eggs, and ejects his milt. If a good selection is fertilized with cuckold spermatozoa, then the fish has accomplished his reproductive duties.