A huge marine mammal known as Steller's sea cow once lived in the waters around Bering Island off the coast of Siberia. It was described in 1741 by Georg W. Steller, a naturalist who was among the first Europeans to see one. In 1768 the animal became extinct. The reasons for the extinction are not clear. Here are three theories about the main cause of the extinction.
First, the sea cows may have been overhunted by groups of native Siberian people. If this theory is correct, then the sea cow population would have originally been quite large, but hundreds of years off too much hunting by the native people diminished the number of sea cows. Sea cows were a good source of food in a harsh environment, so overhunting by native people could have been the main cause of extinction.
Second, the sea cow population may have become extinct because of ecosystems disturbances that caused a decline in their main source of food, kelp (a type of sea plant). Kelp populations respond negatively to a number of ecological changes. It is possible that ecological changes near Bering Island some time before 1768 caused a decrease of the kelp that the sea cows depend on.
Third, the main cause of extinction of the sea cows could have been European fur traders who came to the island after 1741. It is recorded that the fur traders caught the last sea cow in 1768. It thus seems reasonable to believe that hunting by European fur traders, who possessed weapons that allowed them to quickly kill a large number of the animals, was the main cause of the sea cow's extinction.
Both the author and the lecturer are talking about a sea marine mammal, named sea cow which became extinct in 1768. The author believes that this happened for three possible reasons and provides some evidence for his hypothesis. However, the lecturer considers these reasons to be problematic and supports his idea by reasoning.
First of all, the author insists that the main reason for the extinction of the sea cow was the huge amount of hunting done by Siberian people. The lecturer conflicts with this idea. He states that first of all, sea cows were really huge animals and they could supply food for a great deal of time. Moreover, he demonstrates that the Siberian population was not great at that time. Hence, hunting small numbers of sea cows would provide food for people for about a month or so and there were no needs to hunt many of these animals.
Secondly, it has been mentioned in the text that due to some ecosystem disturbances, sea cows might have faced a strict shortage in the population of Kelp which was their main food resource. The lecturer totally disagrees with this idea and describes that there are no reports admitting that there were shortages in other food supplies and therefore if there were any environmental disturbances, they should have been a whole decline in other resources.
Finally, the author insists that the main cause for the extinction of these animals is the advent of European fur traders who were probably hunting them. The lecturer, however, states that the number of sea cows started to demolish for about hundred of years before the arrival of European traders. So, when these traders arrived, there were actually a limited number of sea cows existing in the area. Hence, the reduction in the number of sea cows has nothing to do with the appearance of European traders.
To sum it up, the author has counted three main reasons for the extinction of sea cows. But the lecturer conflicts with all the mentioned reasons and provides support to reject the hypothesis.
Grammar and spelling errors:
Line 4, column 243, Rule ID: NODT_DOZEN[1]
Message: Use simply: 'a hundred'.
Suggestion: a hundred
... sea cows started to demolish for about hundred of years before the arrival of European...
^^^^^^^
Transition Words or Phrases used:
actually, but, finally, first, hence, however, if, moreover, really, second, secondly, so, therefore, talking about, first of all
Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments
Performance on Part of Speech:
To be verbs : 15.0 10.4613686534 143% => OK
Auxiliary verbs: 4.0 5.04856512141 79% => OK
Conjunction : 10.0 7.30242825607 137% => OK
Relative clauses : 14.0 12.0772626932 116% => OK
Pronoun: 27.0 22.412803532 120% => Less pronouns wanted
Preposition: 43.0 30.3222958057 142% => OK
Nominalization: 8.0 5.01324503311 160% => OK
Performance on vocabulary words:
No of characters: 1679.0 1373.03311258 122% => OK
No of words: 345.0 270.72406181 127% => OK
Chars per words: 4.86666666667 5.08290768461 96% => OK
Fourth root words length: 4.3097767484 4.04702891845 106% => OK
Word Length SD: 2.46220581327 2.5805825403 95% => OK
Unique words: 163.0 145.348785872 112% => OK
Unique words percentage: 0.472463768116 0.540411800872 87% => More unique words wanted or less content wanted.
syllable_count: 518.4 419.366225166 124% => OK
avg_syllables_per_word: 1.5 1.55342163355 97% => OK
A sentence (or a clause, phrase) starts by:
Pronoun: 4.0 3.25607064018 123% => OK
Article: 9.0 8.23620309051 109% => OK
Subordination: 1.0 1.25165562914 80% => OK
Conjunction: 1.0 1.51434878587 66% => OK
Preposition: 1.0 2.5761589404 39% => More preposition wanted as sentence beginning.
Performance on sentences:
How many sentences: 16.0 13.0662251656 122% => OK
Sentence length: 21.0 21.2450331126 99% => OK
Sentence length SD: 48.9361829325 49.2860985944 99% => OK
Chars per sentence: 104.9375 110.228320801 95% => OK
Words per sentence: 21.5625 21.698381199 99% => OK
Discourse Markers: 8.0625 7.06452816374 114% => OK
Paragraphs: 5.0 4.09492273731 122% => OK
Language errors: 1.0 4.19205298013 24% => OK
Sentences with positive sentiment : 4.0 4.33554083885 92% => OK
Sentences with negative sentiment : 8.0 4.45695364238 179% => OK
Sentences with neutral sentiment: 4.0 4.27373068433 94% => OK
What are sentences with positive/Negative/neutral sentiment?
Coherence and Cohesion:
Essay topic to essay body coherence: 0.162109401445 0.272083759551 60% => OK
Sentence topic coherence: 0.0622186201913 0.0996497079465 62% => OK
Sentence topic coherence SD: 0.0571387437017 0.0662205650399 86% => OK
Paragraph topic coherence: 0.090186112458 0.162205337803 56% => OK
Paragraph topic coherence SD: 0.0388439288761 0.0443174109184 88% => OK
Essay readability:
automated_readability_index: 12.3 13.3589403974 92% => Automated_readability_index is low.
flesch_reading_ease: 58.62 53.8541721854 109% => OK
smog_index: 3.1 5.55761589404 56% => Smog_index is low.
flesch_kincaid_grade: 10.3 11.0289183223 93% => OK
coleman_liau_index: 10.97 12.2367328918 90% => OK
dale_chall_readability_score: 7.97 8.42419426049 95% => OK
difficult_words: 72.0 63.6247240618 113% => OK
linsear_write_formula: 7.5 10.7273730684 70% => OK
gunning_fog: 10.4 10.498013245 99% => OK
text_standard: 11.0 11.2008830022 98% => OK
What are above readability scores?
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Write the essay in 20 minutes.
Rates: 73.3333333333 out of 100
Scores by essay e-grader: 22.0 Out of 30
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Note: the e-grader does NOT examine the meaning of words and ideas. VIP users will receive further evaluations by advanced module of e-grader and human graders.