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 and the lecture are both about the reasons behind the sea cow extinction. Whereas the reading claims that sea cow extent cause have been hypothesized, the lecture seems adamant that its cause is unknown. The lecturer casts doubt on the main reasons made in the passage to support possible impetus for sea cow extinction.
First of all, according to the author, Siberian may over hunted the sea cows that lead to its extinction. However, the lecturer refutes this point. he argues, size of the sea cow was that massive, nine meter wide and ten ton in weight, could feed the large proportion of the people. In addition, he posits that the size of the Serbian was so small that they did not have to over hunt the animals as its one hunt could substantiate their food source for month.
Secondly, the author blames disturbance of ecological cycle caused decrease in Klep population which is major food source of this animal. As a result, they might get extinct. Nevertheless, the speaker refutes this claim by stating that, like the sea cow many more animals should have been effected by this disturbance; if it was the main cause, the other animals like whale would have been disappeared along it. But, this was not result which proves that there would have no loss of kelp population during that period.
Lastly, the reading posits final cause for the sea cow extinction is european invasion in the territory for the fur purpose. To negate this point, the speaker expounds that the cow's population where in smallest number long before their arrival. that conclude, there must be another reason which caused its extinction not the european people.
Grammar and spelling errors:
Line 7, column 149, Rule ID: UPPERCASE_SENTENCE_START
Message: This sentence does not start with an uppercase letter
Suggestion: He
...wever, the lecturer refutes this point. he argues, size of the sea cow was that ma...
^^
Line 7, column 203, Rule ID: CD_NN[1]
Message: Possible agreement error. The noun 'meter' seems to be countable, so consider using: 'meters'.
Suggestion: meters
...e of the sea cow was that massive, nine meter wide and ten ton in weight, could feed ...
^^^^^
Line 19, column 178, Rule ID: POSSESIVE_APOSTROPHE[1]
Message: Possible typo: apostrophe is missing. Did you mean 'cows'' or 'cow's'?
Suggestion: cows'; cow's
...is point, the speaker expounds that the cows population where in smallest number lon...
^^^^
Line 19, column 200, Rule ID: THE_SUPERLATIVE[2]
Message: A determiner is probably missing here: 'in the smallest'.
Suggestion: in the smallest
...expounds that the cows population where in smallest number long before their arrival. that ...
^^^^^^^^^^^
Line 19, column 246, Rule ID: UPPERCASE_SENTENCE_START
Message: This sentence does not start with an uppercase letter
Suggestion: That
...llest number long before their arrival. that conclude, there must be another reason ...
^^^^
Transition Words or Phrases used:
but, first, however, if, lastly, may, nevertheless, second, secondly, so, whereas, in addition, as a result, first of all
Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments
Performance on Part of Speech:
To be verbs : 12.0 10.4613686534 115% => OK
Auxiliary verbs: 8.0 5.04856512141 158% => OK
Conjunction : 2.0 7.30242825607 27% => More conjunction wanted.
Relative clauses : 15.0 12.0772626932 124% => OK
Pronoun: 29.0 22.412803532 129% => Less pronouns wanted
Preposition: 30.0 30.3222958057 99% => 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: 1398.0 1373.03311258 102% => OK
No of words: 283.0 270.72406181 105% => OK
Chars per words: 4.93992932862 5.08290768461 97% => OK
Fourth root words length: 4.10153676581 4.04702891845 101% => OK
Word Length SD: 2.37712821559 2.5805825403 92% => OK
Unique words: 156.0 145.348785872 107% => OK
Unique words percentage: 0.551236749117 0.540411800872 102% => OK
syllable_count: 417.6 419.366225166 100% => 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: 9.0 8.23620309051 109% => OK
Subordination: 2.0 1.25165562914 160% => OK
Conjunction: 0.0 1.51434878587 0% => OK
Preposition: 4.0 2.5761589404 155% => OK
Performance on sentences:
How many sentences: 14.0 13.0662251656 107% => OK
Sentence length: 20.0 21.2450331126 94% => OK
Sentence length SD: 48.2521015721 49.2860985944 98% => OK
Chars per sentence: 99.8571428571 110.228320801 91% => OK
Words per sentence: 20.2142857143 21.698381199 93% => OK
Discourse Markers: 8.64285714286 7.06452816374 122% => OK
Paragraphs: 4.0 4.09492273731 98% => OK
Language errors: 5.0 4.19205298013 119% => OK
Sentences with positive sentiment : 3.0 4.33554083885 69% => OK
Sentences with negative sentiment : 3.0 4.45695364238 67% => OK
Sentences with neutral sentiment: 8.0 4.27373068433 187% => OK
What are sentences with positive/Negative/neutral sentiment?
Coherence and Cohesion:
Essay topic to essay body coherence: 0.126032366537 0.272083759551 46% => OK
Sentence topic coherence: 0.0444445533282 0.0996497079465 45% => OK
Sentence topic coherence SD: 0.0296151398986 0.0662205650399 45% => Sentences are similar to each other.
Paragraph topic coherence: 0.0787107744601 0.162205337803 49% => OK
Paragraph topic coherence SD: 0.020021194292 0.0443174109184 45% => 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: 11.9 13.3589403974 89% => Automated_readability_index is low.
flesch_reading_ease: 59.64 53.8541721854 111% => OK
smog_index: 3.1 5.55761589404 56% => Smog_index is low.
flesch_kincaid_grade: 9.9 11.0289183223 90% => OK
coleman_liau_index: 11.37 12.2367328918 93% => OK
dale_chall_readability_score: 7.92 8.42419426049 94% => OK
difficult_words: 59.0 63.6247240618 93% => OK
linsear_write_formula: 7.5 10.7273730684 70% => OK
gunning_fog: 10.0 10.498013245 95% => OK
text_standard: 10.0 11.2008830022 89% => OK
What are above readability scores?
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Rates: 75.0 out of 100
Scores by essay e-grader: 22.5 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.