Tuesday, October 22, 2019
Salmon essays
Salmon essays What species would travel over 2000 miles just to have young and then die? It has been said that anyone who has not seen a wild salmon has not seen what a fish should be. Salmon was the common name applied to fish characterized by an elongated body covered with small, rounded scales and a fleshy fin between the dorsal fin and tail. In this paper I will be discussing history of studying salmon, the life cycle, spawning and mating behaviors; which has much to do with the total reproduction of salmon. Salmon were studied earlier than some may think. Experiments were done by men that date back to the mid-1600s. These experiments involved catching salmon in fresh water, tagging them, and then catching them again when they return to the same place, around six months later. These experiments were doubtful and it was not until the beginning of the 1900s that proof was available that the salmon returned home. (Shearer) Although usually drab in color before the breeding season, which varies with the species, members of the salmon family develop bright hues at spawning time. The male, during this mating season, usually develops a hooked snout and a humped back. "In many diverse taxa, males of the same species often exhibit multiple mating strategies. One well-documented alternative male reproductive pattern is 'female mimicry,' whereby males assume a female-like morphology or mimic female behavior patterns. In some species males mimic both female morphology and behavior. We report here female mimicry in a reptile, the red-sided garter snake (Thamnophis sirtalis parietalis). This form of mimicry is unique in that it is expressed as a physiological feminization. Courting male red-sided garter snakes detect a female-specific pheromone and normally avoid courting other males. However, a small proportion of males release a pheromone that attracts other males, as though they were females. In the field, ma ting aggregations of 5...
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