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.
Whereas the reading passage highlights three possible theories for the extinction of sea cows, the lecture refutes these theories for the following reasons.
Firstly, the author assumes that native Siberian people hunted large numbers of sea cows to feed their people in harsh conditions. On the other hand, the professor disagrees with this theory and emphasizes how huge the sea cows. Thus, a couple of sea cows could feed a whole village. He goes on and illustrates that the population of native Siberians wasn’t that big to be not sufficiently fed with just a couple of enormously sized sea cows.
Secondly, the reading passage assumes that sea cows are extinct is because of ecosystem disturbance. This disturbed their main food source which is Kelp. However, the lecturer debates this theory and mentions that the kelp population wasn’t affected by any ecosystem change. Thus, there was no shortage of the main sea cows’ food.
Lastly, the writer believes that European fur traders are the reason for the sea cows’ extinction. The fur traders had large weapons that enabled them to kill a large number of sea cows at the same time. Obviously, the professor debates this theory and states that Europeans reached the island when the sea cows’ population has already diminished. Accordingly, there must be another reason that has caused this tremendous decrease in their numbers before the Europeans’ arrival to the island.
From the professor’s point of view, the theories about sea cow extinction are not well-founded.
Grammar and spelling errors:
Line 4, column 159, Rule ID: LARGE_NUMBER_OF[1]
Message: Specify a number, remove phrase, or simply use 'many' or 'numerous'
Suggestion: many; numerous
...large weapons that enabled them to kill a large number of sea cows at the same time. Obviously, t...
^^^^^^^^^^^^^^^^^
Transition Words or Phrases used:
accordingly, first, firstly, however, lastly, second, secondly, so, thus, well, whereas, on the other hand
Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments
Performance on Part of Speech:
To be verbs : 8.0 10.4613686534 76% => OK
Auxiliary verbs: 2.0 5.04856512141 40% => OK
Conjunction : 4.0 7.30242825607 55% => More conjunction wanted.
Relative clauses : 11.0 12.0772626932 91% => OK
Pronoun: 20.0 22.412803532 89% => OK
Preposition: 24.0 30.3222958057 79% => OK
Nominalization: 7.0 5.01324503311 140% => OK
Performance on vocabulary words:
No of characters: 1298.0 1373.03311258 95% => OK
No of words: 248.0 270.72406181 92% => More content wanted.
Chars per words: 5.23387096774 5.08290768461 103% => OK
Fourth root words length: 3.96837696647 4.04702891845 98% => OK
Word Length SD: 2.63924150725 2.5805825403 102% => OK
Unique words: 139.0 145.348785872 96% => OK
Unique words percentage: 0.560483870968 0.540411800872 104% => OK
syllable_count: 381.6 419.366225166 91% => OK
avg_syllables_per_word: 1.5 1.55342163355 97% => OK
A sentence (or a clause, phrase) starts by:
Pronoun: 2.0 3.25607064018 61% => OK
Article: 10.0 8.23620309051 121% => OK
Subordination: 0.0 1.25165562914 0% => More adverbial clause wanted.
Conjunction: 0.0 1.51434878587 0% => OK
Preposition: 2.0 2.5761589404 78% => OK
Performance on sentences:
How many sentences: 14.0 13.0662251656 107% => OK
Sentence length: 17.0 21.2450331126 80% => The Avg. Sentence Length is relatively short.
Sentence length SD: 35.391109226 49.2860985944 72% => OK
Chars per sentence: 92.7142857143 110.228320801 84% => OK
Words per sentence: 17.7142857143 21.698381199 82% => OK
Discourse Markers: 7.57142857143 7.06452816374 107% => OK
Paragraphs: 5.0 4.09492273731 122% => OK
Language errors: 1.0 4.19205298013 24% => OK
Sentences with positive sentiment : 2.0 4.33554083885 46% => More positive sentences wanted.
Sentences with negative sentiment : 6.0 4.45695364238 135% => OK
Sentences with neutral sentiment: 6.0 4.27373068433 140% => OK
What are sentences with positive/Negative/neutral sentiment?
Coherence and Cohesion:
Essay topic to essay body coherence: 0.136024431748 0.272083759551 50% => OK
Sentence topic coherence: 0.0559129896189 0.0996497079465 56% => OK
Sentence topic coherence SD: 0.0366951057445 0.0662205650399 55% => OK
Paragraph topic coherence: 0.0776552938526 0.162205337803 48% => OK
Paragraph topic coherence SD: 0.02420687646 0.0443174109184 55% => OK
Essay readability:
automated_readability_index: 12.1 13.3589403974 91% => Automated_readability_index is low.
flesch_reading_ease: 62.68 53.8541721854 116% => OK
smog_index: 3.1 5.55761589404 56% => Smog_index is low.
flesch_kincaid_grade: 8.7 11.0289183223 79% => OK
coleman_liau_index: 12.76 12.2367328918 104% => OK
dale_chall_readability_score: 8.3 8.42419426049 99% => OK
difficult_words: 60.0 63.6247240618 94% => 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?
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Rates: 85.0 out of 100
Scores by essay e-grader: 25.5 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.