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 reading is about the possible hypothesis of Stellar sea cow disappearance. It provides three supporting ideas in order to strengthen its claim. However, the professor doubts the validity of these theories. He refutes each of the reading claim.
First, the passage asserts that the excessive hunting by Siberian people causes the extinction of sea cow. But, the lecturer denies this proposition. He says, the sea cow were the massive creature, 9 meter long and 10 tons in weight. In addition, the Siberian people were not needed to hunt the sea cow because their population were not large and also their environment was not rough to depends on sea cow for survive.
Second, the reading states that the imbalance and scarcity of kelp is the reason for sea cow perish. However, the narrator refutes this reasoning. Moreover, he offers, the sea cow were not affected by the imbalance of ecosystem because the kelp were not declined on that time. Furthermore, the fishing of marine vessel were not reported whale decline but they reported the growth of kelp population.
Third, the written excerpt claims that European fur traders is the reason for sea cow destruction. The point is quite problematic with the lecturer. He explains, when the European were went to trade sea cow, the population of sea cow was already small. Moreover, the largest population of sea cow were exist 100 years ago and it was before the European were visited on that area.
Grammar and spelling errors:
Line 3, column 388, Rule ID: TO_NON_BASE[1]
Message: The verb after "to" should be in the base form: 'depend'.
Suggestion: depend
...also their environment was not rough to depends on sea cow for survive. Second, the ...
^^^^^^^
Line 7, column 298, Rule ID: WERE_VBB[1]
Message: Did you mean 'where' or 'we'?
Suggestion: where; we
...over, the largest population of sea cow were exist 100 years ago and it was before t...
^^^^
Transition Words or Phrases used:
also, but, first, furthermore, however, moreover, second, so, then, third, in addition
Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments
Performance on Part of Speech:
To be verbs : 16.0 10.4613686534 153% => OK
Auxiliary verbs: 0.0 5.04856512141 0% => OK
Conjunction : 5.0 7.30242825607 68% => OK
Relative clauses : 6.0 12.0772626932 50% => More relative clauses wanted.
Pronoun: 18.0 22.412803532 80% => OK
Preposition: 25.0 30.3222958057 82% => 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: 1217.0 1373.03311258 89% => OK
No of words: 244.0 270.72406181 90% => More content wanted.
Chars per words: 4.98770491803 5.08290768461 98% => OK
Fourth root words length: 3.95227774224 4.04702891845 98% => OK
Word Length SD: 2.58923969296 2.5805825403 100% => OK
Unique words: 129.0 145.348785872 89% => More unique words wanted.
Unique words percentage: 0.52868852459 0.540411800872 98% => OK
syllable_count: 371.7 419.366225166 89% => OK
avg_syllables_per_word: 1.5 1.55342163355 97% => OK
A sentence (or a clause, phrase) starts by:
Pronoun: 5.0 3.25607064018 154% => OK
Article: 14.0 8.23620309051 170% => OK
Subordination: 1.0 1.25165562914 80% => OK
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: 16.0 13.0662251656 122% => OK
Sentence length: 15.0 21.2450331126 71% => The Avg. Sentence Length is relatively short.
Sentence length SD: 38.4040504862 49.2860985944 78% => OK
Chars per sentence: 76.0625 110.228320801 69% => OK
Words per sentence: 15.25 21.698381199 70% => OK
Discourse Markers: 5.375 7.06452816374 76% => OK
Paragraphs: 4.0 4.09492273731 98% => OK
Language errors: 2.0 4.19205298013 48% => OK
Sentences with positive sentiment : 3.0 4.33554083885 69% => OK
Sentences with negative sentiment : 4.0 4.45695364238 90% => OK
Sentences with neutral sentiment: 9.0 4.27373068433 211% => Less facts, knowledge or examples wanted.
What are sentences with positive/Negative/neutral sentiment?
Coherence and Cohesion:
Essay topic to essay body coherence: 0.149914792765 0.272083759551 55% => OK
Sentence topic coherence: 0.0499534688935 0.0996497079465 50% => OK
Sentence topic coherence SD: 0.0498975431835 0.0662205650399 75% => OK
Paragraph topic coherence: 0.0929529270236 0.162205337803 57% => OK
Paragraph topic coherence SD: 0.0526048629804 0.0443174109184 119% => OK
Essay readability:
automated_readability_index: 9.7 13.3589403974 73% => Automated_readability_index is low.
flesch_reading_ease: 64.71 53.8541721854 120% => OK
smog_index: 3.1 5.55761589404 56% => Smog_index is low.
flesch_kincaid_grade: 8.0 11.0289183223 73% => OK
coleman_liau_index: 11.07 12.2367328918 90% => OK
dale_chall_readability_score: 8.26 8.42419426049 98% => OK
difficult_words: 60.0 63.6247240618 94% => OK
linsear_write_formula: 6.0 10.7273730684 56% => Linsear_write_formula is low.
gunning_fog: 8.0 10.498013245 76% => OK
text_standard: 8.0 11.2008830022 71% => OK
What are above readability scores?
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Rates: 78.3333333333 out of 100
Scores by essay e-grader: 23.5 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.