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 European 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 passage and lecture have conflicting opinions about the main cause of sea cow extinction. The article strongly postulates that there is no clear evidence about the extinction of the sea cow. However, there are three theories discuss the sea cow extinction. On the other hand, the listening adamantly delinates that there is no truth about the extinction of the sea cow, but there are problems with the presented theories.
First and foremost, according to the author of the excerpt, Siberian people were depending on the sea cow as the main source of food in a bad environment. Also, they overhunted the sea cow many decades, thereby decreasing the sea cow numbers significantly. Nonetheless, the lecture offsets these points by declaring that the sea cow was nine meters in length and ten 10 weight, so the sea cow could feed the Siberian people for a month. Also, the population of the Siberian people was quite small.
The professor in the lecture further points out that ecological disturbance couln't affect the kelp only. In other words, all other parts of the system will be affected by ecological distrubance, for instance, deline in the whale's numbers. but the whale number reamained consistent. In fact, the kelp was also growing fine, so no shortage in sea cow food. These claims refute the writer implication of how ecological distrubacne affected the main source of food sea cow, thereby causing the extinct.
The article lastly assertst that the European arrival to the insland caused the sea cows to extinct. Furthermore, the European trader had sophisticated weapons allowed them to hunt a massive number of the sea cow. In contrast, the speaker in the lecture counters these points by insisting that the sea cows extinction happened soon after the Europen came to the insland. However, evidence shows that the sea cows population was arleady declined. Therefore, they were just last who arrived.
Grammar and spelling errors:
Line 3, column 77, Rule ID: PROGRESSIVE_VERBS[1]
Message: This verb is normally not used in the progressive form. Try a simple form instead.
... author of the excerpt, Siberian people were depending on the sea cow as the main source of fo...
^^^^^^^^^^^^^^
Line 5, column 240, Rule ID: UPPERCASE_SENTENCE_START
Message: This sentence does not start with an uppercase letter
Suggestion: But
...instance, deline in the whales numbers. but the whale number reamained consistent. ...
^^^
Line 7, column 303, Rule ID: POSSESIVE_APOSTROPHE[1]
Message: Possible typo: apostrophe is missing. Did you mean 'cows'' or 'cow's'?
Suggestion: cows'; cow's
... these points by insisting that the sea cows extinction happened soon after the Euro...
^^^^
Line 7, column 409, Rule ID: POSSESIVE_APOSTROPHE[1]
Message: Possible typo: apostrophe is missing. Did you mean 'cows'' or 'cow's'?
Suggestion: cows'; cow's
...d. However, evidence shows that the sea cows population was arleady declined. Theref...
^^^^
Transition Words or Phrases used:
also, but, first, furthermore, however, if, lastly, nonetheless, so, therefore, for instance, in contrast, in fact, in other words, on the other hand
Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments
Performance on Part of Speech:
To be verbs : 11.0 10.4613686534 105% => OK
Auxiliary verbs: 2.0 5.04856512141 40% => OK
Conjunction : 5.0 7.30242825607 68% => OK
Relative clauses : 8.0 12.0772626932 66% => More relative clauses wanted.
Pronoun: 13.0 22.412803532 58% => OK
Preposition: 35.0 30.3222958057 115% => OK
Nominalization: 14.0 5.01324503311 279% => Less nominalizations (nouns with a suffix like: tion ment ence ance) wanted.
Performance on vocabulary words:
No of characters: 1618.0 1373.03311258 118% => OK
No of words: 317.0 270.72406181 117% => OK
Chars per words: 5.10410094637 5.08290768461 100% => OK
Fourth root words length: 4.21953715646 4.04702891845 104% => OK
Word Length SD: 2.68296483605 2.5805825403 104% => OK
Unique words: 164.0 145.348785872 113% => OK
Unique words percentage: 0.517350157729 0.540411800872 96% => OK
syllable_count: 495.0 419.366225166 118% => OK
avg_syllables_per_word: 1.6 1.55342163355 103% => OK
A sentence (or a clause, phrase) starts by:
Pronoun: 3.0 3.25607064018 92% => OK
Article: 10.0 8.23620309051 121% => OK
Subordination: 0.0 1.25165562914 0% => More adverbial clause wanted.
Conjunction: 2.0 1.51434878587 132% => OK
Preposition: 5.0 2.5761589404 194% => OK
Performance on sentences:
How many sentences: 18.0 13.0662251656 138% => OK
Sentence length: 17.0 21.2450331126 80% => The Avg. Sentence Length is relatively short.
Sentence length SD: 40.6868878081 49.2860985944 83% => OK
Chars per sentence: 89.8888888889 110.228320801 82% => OK
Words per sentence: 17.6111111111 21.698381199 81% => OK
Discourse Markers: 8.27777777778 7.06452816374 117% => OK
Paragraphs: 4.0 4.09492273731 98% => OK
Language errors: 4.0 4.19205298013 95% => OK
Sentences with positive sentiment : 3.0 4.33554083885 69% => OK
Sentences with negative sentiment : 7.0 4.45695364238 157% => 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: 0.154017060536 0.272083759551 57% => OK
Sentence topic coherence: 0.058623440184 0.0996497079465 59% => OK
Sentence topic coherence SD: 0.0356812272609 0.0662205650399 54% => OK
Paragraph topic coherence: 0.103554926257 0.162205337803 64% => OK
Paragraph topic coherence SD: 0.0344537471364 0.0443174109184 78% => OK
Essay readability:
automated_readability_index: 11.4 13.3589403974 85% => Automated_readability_index is low.
flesch_reading_ease: 54.22 53.8541721854 101% => OK
smog_index: 3.1 5.55761589404 56% => Smog_index is low.
flesch_kincaid_grade: 9.9 11.0289183223 90% => OK
coleman_liau_index: 12.0 12.2367328918 98% => OK
dale_chall_readability_score: 8.51 8.42419426049 101% => OK
difficult_words: 81.0 63.6247240618 127% => OK
linsear_write_formula: 11.0 10.7273730684 103% => OK
gunning_fog: 8.8 10.498013245 84% => OK
text_standard: 9.0 11.2008830022 80% => OK
What are above readability scores?
---------------------
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.