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.
The article states that the reason that sea cows became extinct is not clear and provides three theories for the main reasons of their extinction. However, the professor explains that there are problems with these theories and refutes each of the author's reasons.
First, the reading claims that sea cows may have been overhunted by Siberian people. The professor opposes this point by saying that sea cows were massive creatures that each of them weighed about 10 tons and the Siberian people did not have a large population. He states that a small population cannot hunt a large number of these great animals.
Second, the author posits that the sea cow population may have become extinct because of the ecosystems disturbance which resulted to decline in the population of kelp that was the main source of food for sea cows. Nevertheless, the professor contends that if there were a ecosystems disturbances, other animals such as whales became extinct too. According to the professor, there was no report about the decline in whale's population and the population of kelp would have grown fine in that time.
Third, the article avers that the main cause of the extinction of sea cows could have been Europian fur traders that hunted them by their great weapons. The professor refutes this reason by explaining that the population of sea cows had been decreased long before Europian traders reached there. Based on the lecture there should be other reasons for the extinction of these creatures which caused their population decreases about 100 years before Europian arrives there.
Grammar and spelling errors:
Line 3, column 309, Rule ID: LARGE_NUMBER_OF[1]
Message: Specify a number, remove phrase, or simply use 'many' or 'numerous'
Suggestion: many; numerous
...tes that a small population cannot hunt a large number of these great animals. Second, the aut...
^^^^^^^^^^^^^^^^^
Line 5, column 94, Rule ID: POSSESIVE_APOSTROPHE[1]
Message: Possible typo: apostrophe is missing. Did you mean 'ecosystems'' or 'ecosystem's'?
Suggestion: ecosystems'; ecosystem's
... may have become extinct because of the ecosystems disturbance which resulted to decline i...
^^^^^^^^^^
Line 5, column 272, Rule ID: EN_A_VS_AN
Message: Use 'an' instead of 'a' if the following word starts with a vowel sound, e.g. 'an article', 'an hour'
Suggestion: an
...e professor contends that if there were a ecosystems disturbances, other animals ...
^
Transition Words or Phrases used:
first, however, if, may, nevertheless, second, so, third, such as
Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments
Performance on Part of Speech:
To be verbs : 10.0 10.4613686534 96% => OK
Auxiliary verbs: 6.0 5.04856512141 119% => OK
Conjunction : 4.0 7.30242825607 55% => More conjunction wanted.
Relative clauses : 16.0 12.0772626932 132% => OK
Pronoun: 25.0 22.412803532 112% => OK
Preposition: 28.0 30.3222958057 92% => OK
Nominalization: 12.0 5.01324503311 239% => Less nominalizations (nouns with a suffix like: tion ment ence ance) wanted.
Performance on vocabulary words:
No of characters: 1331.0 1373.03311258 97% => OK
No of words: 261.0 270.72406181 96% => OK
Chars per words: 5.09961685824 5.08290768461 100% => OK
Fourth root words length: 4.0193898071 4.04702891845 99% => OK
Word Length SD: 2.45515256305 2.5805825403 95% => OK
Unique words: 132.0 145.348785872 91% => More unique words wanted.
Unique words percentage: 0.505747126437 0.540411800872 94% => More unique words wanted or less content wanted.
syllable_count: 399.6 419.366225166 95% => OK
avg_syllables_per_word: 1.5 1.55342163355 97% => OK
A sentence (or a clause, phrase) starts by:
Pronoun: 1.0 3.25607064018 31% => OK
Article: 8.0 8.23620309051 97% => OK
Subordination: 0.0 1.25165562914 0% => More adverbial clause wanted.
Conjunction: 0.0 1.51434878587 0% => OK
Preposition: 1.0 2.5761589404 39% => More preposition wanted as sentence beginning.
Performance on sentences:
How many sentences: 11.0 13.0662251656 84% => Need more sentences. Double check the format of sentences, make sure there is a space between two sentences, or have enough periods. And also check the lengths of sentences, maybe they are too long.
Sentence length: 23.0 21.2450331126 108% => OK
Sentence length SD: 37.0681748509 49.2860985944 75% => OK
Chars per sentence: 121.0 110.228320801 110% => OK
Words per sentence: 23.7272727273 21.698381199 109% => OK
Discourse Markers: 5.90909090909 7.06452816374 84% => OK
Paragraphs: 4.0 4.09492273731 98% => OK
Language errors: 3.0 4.19205298013 72% => OK
Sentences with positive sentiment : 3.0 4.33554083885 69% => OK
Sentences with negative sentiment : 5.0 4.45695364238 112% => OK
Sentences with neutral sentiment: 3.0 4.27373068433 70% => OK
What are sentences with positive/Negative/neutral sentiment?
Coherence and Cohesion:
Essay topic to essay body coherence: 0.0893282102125 0.272083759551 33% => The similarity between the topic and the content is low.
Sentence topic coherence: 0.0393218423586 0.0996497079465 39% => Sentence topic similarity is low.
Sentence topic coherence SD: 0.0285886694176 0.0662205650399 43% => Sentences are similar to each other.
Paragraph topic coherence: 0.0575379811281 0.162205337803 35% => Maybe some paragraphs are off the topic.
Paragraph topic coherence SD: 0.0194631638687 0.0443174109184 44% => Paragraphs are similar to each other. Some content may get duplicated or it is not exactly right on the topic.
Essay readability:
automated_readability_index: 14.5 13.3589403974 109% => OK
flesch_reading_ease: 56.59 53.8541721854 105% => OK
smog_index: 8.8 5.55761589404 158% => OK
flesch_kincaid_grade: 11.1 11.0289183223 101% => OK
coleman_liau_index: 12.6 12.2367328918 103% => OK
dale_chall_readability_score: 7.86 8.42419426049 93% => OK
difficult_words: 51.0 63.6247240618 80% => More difficult words wanted.
linsear_write_formula: 10.5 10.7273730684 98% => OK
gunning_fog: 11.2 10.498013245 107% => OK
text_standard: 11.0 11.2008830022 98% => OK
What are above readability scores?
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It is not exactly right on the topic in the view of e-grader. Maybe there is a wrong essay topic.
Rates: 3.33333333333 out of 100
Scores by essay e-grader: 1.0 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.