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.
Based on the given materials, the article as well as the lecturer discusses possible reasons of the extinction of a marine animal called Steller's cow. The author states that their natural habitat was around Siberia and became extinct 1768. That being said, the lecturer asserts some ideas to repudiate this claim.
Initially, the reading alleged that a possible reason might be over-hunting by native settlers since the animal could be a good source of food in the harsh climate of the area. However, the listening explains that these animals were enormous and could weight more than ten tons while the vicinity contained only a small population. So native people did not need to hunt lots of these animals since only a hunt could feed them for a long time. As a result over-hunting is not the reason for their extinction.
Second, the writer proclaims that a disturbance in the environment might be a possible explanation because the Steller's sea cow feed on Kelps, a kind of sea plant, and they can decline because of various reasons. Yet again, the lecturer underscores that if a broad environmental change would have happened, it would affect other species too. He alludes to whales that live at the same area and an environmental change would have affect them too but there is no report of such phenomena by fishing boats around that time and as result a a disrupt in the ecosystem is not a good reason for the extinction.
The last point of contention between the reading and listening passages is fur traders who foot in the island prior to their extinction. Also fur trader caught the animal with their advanced tools too so they were able to kill the fish efficiently. On the other hand, the author explains that the population of these marine animals were already depleted when the traders arrived. Their population were at its highest point one hundred years before traders advent so whatever was the cause of their perish, would have happened before the traders arrival.
Grammar and spelling errors:
Line 9, column 287, Rule ID: IF_WOULD_HAVE_VBN[1]
Message: Did you mean 'had happened'?
Suggestion: had happened
...es that if a broad environmental change would have happened, it would affect other species too. He ...
^^^^^^^^^^^^^^^^^^^
Line 9, column 535, Rule ID: ENGLISH_WORD_REPEAT_RULE
Message: Possible typo: you repeated a word
Suggestion: a
...ng boats around that time and as result a a disrupt in the ecosystem is not a good ...
^^^
Line 9, column 535, 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
...ng boats around that time and as result a a disrupt in the ecosystem is not a goo...
^
Line 9, column 535, Rule ID: DT_DT[1]
Message: Maybe you need to remove one determiner so that only 'a' or 'a' is left.
Suggestion: a; a
...ng boats around that time and as result a a disrupt in the ecosystem is not a good ...
^^^
Line 9, column 537, Rule ID: A_INFINITVE[1]
Message: Probably a wrong construction: a/the + infinitive
... boats around that time and as result a a disrupt in the ecosystem is not a good reason f...
^^^^^^^^^
Line 13, column 138, Rule ID: SENT_START_CONJUNCTIVE_LINKING_ADVERB_COMMA[1]
Message: Did you forget a comma after a conjunctive/linking adverb?
Suggestion: Also,
...n the island prior to their extinction. Also fur trader caught the animal with their...
^^^^
Line 13, column 538, Rule ID: POSSESIVE_APOSTROPHE[2]
Message: Possible typo: apostrophe is missing. Did you mean 'traders'' or 'trader's'?
Suggestion: traders'; trader's
... perish, would have happened before the traders arrival.
^^^^^^^
Transition Words or Phrases used:
also, but, however, if, second, so, well, while, as to, kind of, as a result, as well as, on the other hand
Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments
Performance on Part of Speech:
To be verbs : 14.0 10.4613686534 134% => OK
Auxiliary verbs: 11.0 5.04856512141 218% => Less auxiliary verb wanted.
Conjunction : 8.0 7.30242825607 110% => OK
Relative clauses : 11.0 12.0772626932 91% => OK
Pronoun: 26.0 22.412803532 116% => OK
Preposition: 37.0 30.3222958057 122% => OK
Nominalization: 11.0 5.01324503311 219% => Less nominalizations (nouns with a suffix like: tion ment ence ance) wanted.
Performance on vocabulary words:
No of characters: 1660.0 1373.03311258 121% => OK
No of words: 338.0 270.72406181 125% => OK
Chars per words: 4.91124260355 5.08290768461 97% => OK
Fourth root words length: 4.28774723029 4.04702891845 106% => OK
Word Length SD: 2.52043918871 2.5805825403 98% => OK
Unique words: 185.0 145.348785872 127% => OK
Unique words percentage: 0.547337278107 0.540411800872 101% => OK
syllable_count: 514.8 419.366225166 123% => OK
avg_syllables_per_word: 1.5 1.55342163355 97% => OK
A sentence (or a clause, phrase) starts by:
Pronoun: 4.0 3.25607064018 123% => OK
Article: 10.0 8.23620309051 121% => OK
Subordination: 1.0 1.25165562914 80% => OK
Conjunction: 2.0 1.51434878587 132% => OK
Preposition: 1.0 2.5761589404 39% => More preposition wanted as sentence beginning.
Performance on sentences:
How many sentences: 14.0 13.0662251656 107% => OK
Sentence length: 24.0 21.2450331126 113% => OK
Sentence length SD: 51.7365776737 49.2860985944 105% => OK
Chars per sentence: 118.571428571 110.228320801 108% => OK
Words per sentence: 24.1428571429 21.698381199 111% => OK
Discourse Markers: 7.64285714286 7.06452816374 108% => OK
Paragraphs: 4.0 4.09492273731 98% => OK
Language errors: 7.0 4.19205298013 167% => 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: 0.127839161832 0.272083759551 47% => OK
Sentence topic coherence: 0.0447650874139 0.0996497079465 45% => OK
Sentence topic coherence SD: 0.0492151105812 0.0662205650399 74% => OK
Paragraph topic coherence: 0.0816516271249 0.162205337803 50% => OK
Paragraph topic coherence SD: 0.0543277911959 0.0443174109184 123% => OK
Essay readability:
automated_readability_index: 13.8 13.3589403974 103% => OK
flesch_reading_ease: 55.58 53.8541721854 103% => OK
smog_index: 8.8 5.55761589404 158% => OK
flesch_kincaid_grade: 11.5 11.0289183223 104% => OK
coleman_liau_index: 11.49 12.2367328918 94% => OK
dale_chall_readability_score: 8.24 8.42419426049 98% => OK
difficult_words: 73.0 63.6247240618 115% => OK
linsear_write_formula: 10.5 10.7273730684 98% => OK
gunning_fog: 11.6 10.498013245 110% => OK
text_standard: 12.0 11.2008830022 107% => OK
What are above readability scores?
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Write the essay in 20 minutes.
Rates: 80.0 out of 100
Scores by essay e-grader: 24.0 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.