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.
In this set of material, the reading provides some evidences that suppose some hypothesizes about extinction of Stellar's sea cow, but the lecturer refuse them by giving explanation.
First, the reading claim that native Siberian people may use sea cows as main resources of food and they overhunted them because they were a good and reliable source of food. So, due to overhunting, population of Stellar's sea cow decreased over the time. In contrast, the lecturer rejects this idea by describing size and weight of sea cow; 90 meter long and 900 kilogram! He claimed that native people didn't need to hunt this creatures in a large scale because they could alive by just haunting couple of them for long period of time. So, some other reasons except ot this idea can be the main reason of extinction.
Second, as reading says, population of kelp, which was the main food source of sea cows, were decreased enormously because of ecological fluctuations. But, the lecturer gave explanations against to the claim. He believes that if kelps' population was affected by ecological changes, why these changes didn't impacted other creatures like whales too? As he told, reports from fish hunting ships didn't mentioned any shortages in quantity of fishes. So, this hypothesis could not be true.
Third, reading believes that the main reason for sea cow' disappearance could be European fur trades who hunted sea cows to obtain their fur and sell them in market. They usually used weapons and guns that able them to hunt many Stellar's sea cow in a short period of time. On the contrary, the lecturer rejected this viewpoint too. Based on his speeches, population of Stellar's sea cow were reduced before European fur trades arrive to Bering island. So, European fur trades were not able to access and hunt many sea cows because their population was already diminished.
In conclusion, maybe there is some other reasons exist that can explain Stellar's sea cows extinction.
Grammar and spelling errors:
Line 3, column 1, Rule ID: WHITESPACE_RULE
Message: Possible typo: you repeated a whitespace
Suggestion:
... refuse them by giving explanation. First, the reading claim that native Sib...
^^
Line 3, column 171, Rule ID: WHITESPACE_RULE
Message: Possible typo: you repeated a whitespace
Suggestion:
... they were a good and reliable source of food. So, due to overhunting, population...
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Line 3, column 367, Rule ID: CD_NN[1]
Message: Possible agreement error. The noun 'kilogram' seems to be countable, so consider using: 'kilograms'.
Suggestion: kilograms
...eight of sea cow; 90 meter long and 900 kilogram! He claimed that native people didnt ne...
^^^^^^^^
Line 3, column 407, Rule ID: EN_CONTRACTION_SPELLING
Message: Possible spelling mistake found
Suggestion: didn't
...kilogram! He claimed that native people didnt need to hunt this creatures in a large ...
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Line 3, column 426, Rule ID: THIS_NNS[1]
Message: Did you mean 'these'?
Suggestion: these
...d that native people didnt need to hunt this creatures in a large scale because they...
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Line 3, column 524, Rule ID: PERIOD_OF_TIME[1]
Message: Use simply 'period'.
Suggestion: period
...y just haunting couple of them for long period of time. So, some other reasons except ot this ...
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Line 5, column 1, Rule ID: WHITESPACE_RULE
Message: Possible typo: you repeated a whitespace
Suggestion:
...an be the main reason of extinction. Second, as reading says, population of k...
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Line 5, column 303, Rule ID: EN_CONTRACTION_SPELLING
Message: Possible spelling mistake found
Suggestion: didn't
...y ecological changes, why these changes didnt impacted other creatures like whales to...
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Line 5, column 395, Rule ID: EN_CONTRACTION_SPELLING
Message: Possible spelling mistake found
Suggestion: didn't
...e told, reports from fish hunting ships didnt mentioned any shortages in quantity of ...
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Line 7, column 1, Rule ID: WHITESPACE_RULE
Message: Possible typo: you repeated a whitespace
Suggestion:
..., this hypothesis could not be true. Third, reading believes that the main re...
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Line 7, column 259, Rule ID: PERIOD_OF_TIME[1]
Message: Use simply 'period'.
Suggestion: period
...o hunt many Stellars sea cow in a short period of time. On the contrary, the lecturer rejected...
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Line 7, column 437, Rule ID: WHITESPACE_RULE
Message: Possible typo: you repeated a whitespace
Suggestion:
...ced before European fur trades arrive to Bering island. So, European fur trades w...
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Line 9, column 1, Rule ID: WHITESPACE_RULE
Message: Possible typo: you repeated a whitespace
Suggestion:
... population was already diminished. In conclusion, maybe there is some other...
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Transition Words or Phrases used:
but, first, if, may, second, so, third, in conclusion, in contrast, on the contrary
Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments
Performance on Part of Speech:
To be verbs : 11.0 15.1003584229 73% => OK
Auxiliary verbs: 7.0 9.8082437276 71% => OK
Conjunction : 8.0 13.8261648746 58% => More conjunction wanted.
Relative clauses : 9.0 11.0286738351 82% => OK
Pronoun: 29.0 43.0788530466 67% => OK
Preposition: 42.0 52.1666666667 81% => OK
Nominalization: 10.0 8.0752688172 124% => OK
Performance on vocabulary words:
No of characters: 1643.0 1977.66487455 83% => OK
No of words: 328.0 407.700716846 80% => More content wanted.
Chars per words: 5.00914634146 4.8611393121 103% => OK
Fourth root words length: 4.25567506705 4.48103885553 95% => OK
Word Length SD: 2.54381408716 2.67179642975 95% => OK
Unique words: 171.0 212.727598566 80% => More unique words wanted.
Unique words percentage: 0.521341463415 0.524837075471 99% => OK
syllable_count: 500.4 618.680645161 81% => OK
avg_syllables_per_word: 1.5 1.51630824373 99% => OK
A sentence (or a clause, phrase) starts by:
Pronoun: 4.0 9.59856630824 42% => OK
Interrogative: 1.0 0.994623655914 101% => OK
Article: 5.0 3.08781362007 162% => OK
Subordination: 2.0 3.51792114695 57% => OK
Conjunction: 1.0 1.86738351254 54% => OK
Preposition: 4.0 4.94265232975 81% => OK
Performance on sentences:
How many sentences: 16.0 20.6003584229 78% => 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: 20.0 20.1344086022 99% => OK
Sentence length SD: 58.3263649112 48.9658058833 119% => OK
Chars per sentence: 102.6875 100.406767564 102% => OK
Words per sentence: 20.5 20.6045352989 99% => OK
Discourse Markers: 5.1875 5.45110844103 95% => OK
Paragraphs: 5.0 4.53405017921 110% => OK
Language errors: 13.0 5.5376344086 235% => Less language errors wanted.
Sentences with positive sentiment : 4.0 11.8709677419 34% => More positive sentences wanted.
Sentences with negative sentiment : 4.0 3.85842293907 104% => OK
Sentences with neutral sentiment: 8.0 4.88709677419 164% => OK
What are sentences with positive/Negative/neutral sentiment?
Coherence and Cohesion:
Essay topic to essay body coherence: 0.120819783755 0.236089414692 51% => OK
Sentence topic coherence: 0.0440816273966 0.076458572812 58% => OK
Sentence topic coherence SD: 0.0380433242122 0.0737576698707 52% => OK
Paragraph topic coherence: 0.0673191403045 0.150856017488 45% => OK
Paragraph topic coherence SD: 0.0364577151774 0.0645574589148 56% => OK
Essay readability:
automated_readability_index: 12.4 11.7677419355 105% => OK
flesch_reading_ease: 59.64 58.1214874552 103% => OK
smog_index: 8.8 6.10430107527 144% => OK
flesch_kincaid_grade: 9.9 10.1575268817 97% => OK
coleman_liau_index: 11.78 10.9000537634 108% => OK
dale_chall_readability_score: 7.85 8.01818996416 98% => OK
difficult_words: 67.0 86.8835125448 77% => More difficult words wanted.
linsear_write_formula: 14.0 10.002688172 140% => OK
gunning_fog: 10.0 10.0537634409 99% => OK
text_standard: 10.0 10.247311828 98% => OK
What are above readability scores?
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We are expecting: No. of Words: 350 while No. of Different Words: 200
Rates: 70.0 out of 100
Scores by essay e-grader: 21.0 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.