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# In order to withstand tidal currents, juvenile horseshoe

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Director
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In order to withstand tidal currents, juvenile horseshoe  [#permalink]

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29 Jul 2010, 12:47
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In order to withstand tidal currents, juvenile horseshoe crabs frequently burrow in the sand. Such burrowing discourages barnacles from clinging to their shells. When fully grown, however, the crabs can readily withstand tidal currents without burrowing, and thus they acquire substantial populations of barnacles. Surprisingly, in areas where tidal currents are very weak, juvenile horseshoe crabs are found not to have significant barnacle populations, even though they seldom burrow.

Which of the following, if true, most helps to explain the surprising finding?

(A) Tidal currents do not themselves dislodge barnacles from the shells of horseshoe crabs.
(B) Barnacles most readily attach themselves to horseshoe crabs in areas where tidal currents are weakest.
(C) The strength of the tidal currents in a given location varies widely over the course of a day.
(D) A very large barnacle population can significantly decrease the ability of a horseshoe crab to find food.
(E) Until they are fully grown, horseshoe crabs shed their shells and grow new ones several times a year.

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Re: juvenile horseshoe  [#permalink]

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13 Aug 2010, 11:34
17
5
E
The question statement first establishes a cause and effect relationship: burrowing causes lack of barnacles. The question then states an observation that non-burrowing crabs do not have barnacles. The observation is inconsistent with the cause and effect relationship that was previously stated. Thus, we must find a new cause for a crab's lack of barnacles in order to explain the surprising finding. Answer "E" establishes a new cause: frequent shell shedding.
##### General Discussion
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Re: juvenile horseshoe  [#permalink]

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05 Aug 2010, 19:09
9
This is an OG Question Q No: 59, OG12.
We are apparently asked to resolve the paradox that although the tidal currents are weak and crabs don't burrow, the barnacle population is weak.
A. this gives a reason y there is significant barnacles in crabs that do not burrow. We are not looking out for this answer. Rather we want an answer that explains why there is less barnacle population.
B. This gives an additional premise for the argument and triggers more intrigues as to y there is less population of barnacles even though there are weak tidal currents.
C. Out of scope.
D. Out of scope. Nowhere in the argument, Food comes into picture.
E. Correct answer. This explains why Juvenile crabs have less barnacle population. When they shed their shells regularly, they also shed the barnacles that cling to them regularly. Thus, this explains the surprising finding.

Correct me if I'm wrong.

Thanks.
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Re: juvenile horseshoe  [#permalink]

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06 Aug 2010, 07:38
I picked E too because it explains why in areas of weak tidal currents there is lesser barnacle population. Because crabs shed their shells the barnacles are clinged on to the shedded shells and hence are not seen much clinged on to the carbs. (thus less population).
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Re: juvenile horseshoe  [#permalink]

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16 Aug 2010, 09:19
1
i am still not able to stand why E is correct answer.the statement E have same effect whether horseshoe crabs stay in strong tide current region or weak tide current region.how it explain the low population of barnacle in weak tidal current area.
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Re: juvenile horseshoe  [#permalink]

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17 Aug 2010, 10:17
1
This is a Resolve the paradox Question.The Paradox is when the tides hit the Adult Crabs there will be barnacles attched to them But in weak tide (this is a decoy)areas even though the tides hit Juvenile crabs there are not more barnacles.The correct ans choice must allow both the facts to be true and explain the paradox.Only Option E tells how the Juveniles shed the shell and hence have no barnacles if Adults they wud have had clusters of Barnacles too
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Re: In order to withstand tidal currents, juvenile horseshoe  [#permalink]

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20 Nov 2011, 18:28
1
E explain why there are less barnacles on the shell of the crab, it is not because sand or tidal wave strenght but because the crab 'shed their shells and grow new ones several times a year'
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Re: In order to withstand tidal currents, juvenile horseshoe  [#permalink]

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21 Aug 2012, 07:11
3
This is an Explain the Paradox question type!

Premises:
- juvenile horseshoe crabs frequestly burrow in sand to withstand tidal currents
- burrowing discourages barnacles from clinging to juvie's shells
- fully grown horseshoe crabs can readily withstand tidal currents without burrowing and therefore acquire substancial populations of barnacles

Conc:
- in areas where tidal currents are weak, juvenile horshoe crabs found not ot have significant barnacle populations, even though theyy seldom burrow

a) we already know that BURROWING does. this does not explain anything.
b) then there should be MORE barnacles on their shells.. opp direction
c) tempting but doesn't FULL explain... what is the range of this strength? doesn't really answer our discrepancy
d) out of scope.
e) bingo! if horse shoe crabs are shedding their shells and growing new ones, this w ould explain why we didnt find significant barnacles on their shells even though they weren't burrowing.

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Re: In order to withstand tidal currents, juvenile horseshoe  [#permalink]

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27 Aug 2012, 12:53
noboru wrote:
In order to withstand tidal currents, juvenile horseshoe crabs frequently burrow in the sand. Such burrowing discourages barnacles from clinging to their shells. When fully grown, however, the crabs can readily withstand tidal currents without burrowing, and thus they acquire substantial populations of barnacles. Surprisingly, in areas where tidal currents are very weak, juvenile horseshoe crabs are found not to have significant barnacle populations, even though they seldom burrow.

Which of the following, if true, most helps to explain the surprising finding?

(A) Tidal currents do not themselves dislodge barnacles from the shells of horseshoe crabs.
(B) Barnacles most readily attach themselves to horseshoe crabs in areas where tidal currents are weakest.
(C) The strength of the tidal currents in a given location varies widely over the course of a day.
(D) A very large barnacle population can significantly decrease the ability of a horseshoe crab to find food.
(E) Until they are fully grown, horseshoe crabs shed their shells and grow new ones several times a year.

I had a really hard time understanding Choice A. I'm wondering if my thought process is correct in disqualifying A now.

Here's how I understand the argument:
- high tidal waves --> more burrowing for juvenile horseshoe crabs --> decreased barnacles
BUT ALSO
- low tidal waves --> less burrowing for juvenile horseshoe crabs --> decreased barnacles
how can this be?

A. Tells us that the water tides don't matter. So the less or more barnacle populations have to do with burrowing then (given the premises). So we are left with the situation where:
- more burrowing --> less barnacle population
- less burrowing --> less barnacle population
So...we still have a paradox.

Is this accurate?
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Re: In order to withstand tidal currents, juvenile horseshoe  [#permalink]

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30 Aug 2012, 00:57
1
A really good question. Going through the above posts I understand that this one is from OG12. Took me a really long time at close to 3 mins to reach E. I had to re-read the question stem to resolve this one.

The key to this question is spotting the word "Juvenile". The last statement is about the "juvenile" crabs and not the full grown ones. This makes the statement about full-grown crabs not having to burrow irrelevant in the given argument.

E correctly gives us a reason as to why not a large population of barnacles was not found i.e. since the juvenile crabs shed their shells regularly till full grown.
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Re: In order to withstand tidal currents, juvenile horseshoe  [#permalink]

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30 Aug 2012, 01:09
1
dpvtank wrote:
noboru wrote:
In order to withstand tidal currents, juvenile horseshoe crabs frequently burrow in the sand. Such burrowing discourages barnacles from clinging to their shells. When fully grown, however, the crabs can readily withstand tidal currents without burrowing, and thus they acquire substantial populations of barnacles. Surprisingly, in areas where tidal currents are very weak, juvenile horseshoe crabs are found not to have significant barnacle populations, even though they seldom burrow.

Which of the following, if true, most helps to explain the surprising finding?

(A) Tidal currents do not themselves dislodge barnacles from the shells of horseshoe crabs.
(B) Barnacles most readily attach themselves to horseshoe crabs in areas where tidal currents are weakest.
(C) The strength of the tidal currents in a given location varies widely over the course of a day.
(D) A very large barnacle population can significantly decrease the ability of a horseshoe crab to find food.
(E) Until they are fully grown, horseshoe crabs shed their shells and grow new ones several times a year.

I had a really hard time understanding Choice A. I'm wondering if my thought process is correct in disqualifying A now.

Here's how I understand the argument:
- high tidal waves --> more burrowing for juvenile horseshoe crabs --> decreased barnacles
BUT ALSO
- low tidal waves --> less burrowing for juvenile horseshoe crabs --> decreased barnacles
how can this be?

A. Tells us that the water tides don't matter. So the less or more barnacle populations have to do with burrowing then (given the premises). So we are left with the situation where:
- more burrowing --> less barnacle population
- less burrowing --> less barnacle population
So...we still have a paradox.

Is this accurate?

Let me take a dig at trying to explain the answer choice.

Choice A says that the tidal ways do not dislodge the barnacles from the crab-shells. Thus high or low tidal waves should not make a difference in the population of barnacles, instead burrowing should make all the difference i.e. less burrowing = more barnacles and vice-versa.

Hence in low tidal waves areas the juvenile crabs would burrow less hence ideally the population of barnacles on the juvenile crabs should be larger. However this is contrary to the observed phenomenon i.e. in low tidal areas the barnacle population on juvenile crabs was not found to be larger. Thus option A does not help us resolve the paradox. Hence A can be eliminated.

Hope this helps.
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Re: In order to withstand tidal currents, juvenile horseshoe  [#permalink]

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07 Oct 2012, 04:47
I also selected E as the answer but i have a small doubt . what if the there are fully grown crabs in the weak tidal current area also , then choice e would not hold true because according to the answer choice fully grown crabs won't shed their shells. also in the premise the fully grown crabs have the maximum barnicles. do we have to assume that the weak tidal area do not have a substantial population of fully grown crabs ?
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Re: In order to withstand tidal currents, juvenile horseshoe  [#permalink]

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07 Oct 2012, 23:27
In order to withstand tidal currents, juvenile horseshoe crabs frequently burrow in the sand. Such burrowing discourages barnacles from clinging to their shells. When fully grown, however, the crabs can readily withstand tidal currents without burrowing, and thus they acquire substantial populations of barnacles. Surprisingly, in areas where tidal currents are very weak, juvenile horseshoe crabs are found not to have significant barnacle populations, even though they seldom burrow.

Which of the following, if true, most helps to explain the surprising finding?

(A) Tidal currents do not themselves dislodge barnacles from the shells of horseshoe crabs.
(B) Barnacles most readily attach themselves to horseshoe crabs in areas where tidal currents are weakest.
(C) The strength of the tidal currents in a given location varies widely over the course of a day.
(D) A very large barnacle population can significantly decrease the ability of a horseshoe crab to find food.
(E) Until they are fully grown, horseshoe crabs shed their shells and grow new ones several times a year.

This is more of a resolve the paradox question. Here E gives us a clear explanation of why the finding is surprised.
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Re: In order to withstand tidal currents, juvenile horseshoe  [#permalink]

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29 Apr 2013, 06:15
The paradox is about the juvenile crabs only. Information about Adults is given to highlight that tidal currents causes juveniles to burrow --> burrowing leads to shedding of barnacle population. Essentially, the argument attributes the lack of barnacle population on juvenile crabs to the act of burrowing.

However, there is a paradox because even in weak tidal current areas where burrowing does not happen, the lack of barnacle population on juvenile crabs is observed.

How to resolve the paradox? By attributing the lack of barnacle population on juvenile crabs to something else than the tidal currents. Choice E solves that. If there is some other reason than what is assumed, then the paradox is solved!
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Re: In order to withstand tidal currents, juvenile horseshoe  [#permalink]

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14 Jun 2015, 07:16
1
My 2 cents:

In order to withstand tidal currents, juvenile horseshoe crabs frequently burrow in the sand. Such burrowing discourages barnacles from clinging to their shells.
When fully grown, however, the crabs can readily withstand tidal currents without burrowing, and thus they acquire substantial populations of barnacles.
Surprisingly, in areas where tidal currents are very weak, juvenile horseshoe crabs are found not to have significant barnacle populations, even though they seldom burrow.

Which of the following, if true, most helps to explain the surprising finding?
(A) Tidal currents do not themselves dislodge barnacles from the shells of horseshoe crabs.
>>Evident from argument "burrowing discourages barnacles from clinging". Doesn't help in answering the paradox.
(B) Barnacles most readily attach themselves to horseshoe crabs in areas where tidal currents are weakest.
>>But juvenile horseshoe crabs are found not to have significant barnacle populations in such areas. Doesn't help.
(C) The strength of the tidal currents in a given location varies widely over the course of a day.
>> I found this one intriguing. but this means Barnacle population shouldnt vary much because of variation in tidal strength.
(D) A very large barnacle population can significantly decrease the ability of a horseshoe crab to find food.
>>Irrelevant.
(E) Until they are fully grown, horseshoe crabs shed their shells and grow new ones several times a year.
>>Now apart from sand borrowing this is anther reason for low barnacle population. This answers bth part of argument.
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In order to withstand tidal currents, juvenile horseshoe  [#permalink]

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17 Jun 2015, 14:13
In order to withstand tidal currents, juvenile horseshoe crabs frequently burrow in the sand. Such burrowing discourages barnacles from clinging to their shells. When fully grown, however, the crabs can readily withstand tidal currents without burrowing, and thus they acquire substantial populations of barnacles. Surprisingly, in areas where tidal currents are very weak, juvenile horseshoe crabs are found not to have significant barnacle populations, even though they seldom burrow.

Which of the following, if true, most helps to explain the surprising finding?

The question to answer is, why do juvenile horseshoe crabs have sparse barnacle populations although they aren't burrowing (Burrowing decreases barnacle accumulation)?

(A) Tidal currents do not themselves dislodge barnacles from the shells of horseshoe crabs. doesn't answer the question
(B) Barnacles most readily attach themselves to horseshoe crabs in areas where tidal currents are weakest. This would have the opposite effect.
(C) The strength of the tidal currents in a given location varies widely over the course of a day. not relevant to our question
(D) A very large barnacle population can significantly decrease the ability of a horseshoe crab to find food. also out of scope
(E) Until they are fully grown, horseshoe crabs shed their shells and grow new ones several times a year. This explains why they don't have barnacles although we would think they would because they don't burrow. They shed the barnacles along with their shells.
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In order to withstand tidal currents, juvenile horseshoe  [#permalink]

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07 Sep 2016, 08:49
Hi guys,

Pardon me for bring up this post.

I am quite not satisfied with E. This is my reasoning why:
(E) Until they are fully grown, horseshoe crabs shed their shells and grow new ones several times a year.
The passage states that "Surprisingly, inareas where tidal currents are very weak, juvenile horseshoe crabs are found not to have significant barnacle populations, even though they seldom burrow."

So, in E,the crab is mature and thus can shed its shell; but in the quoted above, the crab is just a kid, this mean it can not shed its shell. The choice turns out irrelevant, or at least can not explain the paradox (to me, of course). So I eliminated E.
IMO, If something can fill the gap between the quoted and E, states or implies, it is "juvenile crab is fully grown". Is it correct?

Could somebody point out the flaw in my reasoning? Thanks in advance.
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Re: In order to withstand tidal currents, juvenile horseshoe  [#permalink]

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30 Jan 2017, 09:06
ThangLe wrote:
Hi guys,

Pardon me for bring up this post.

I am quite not satisfied with E. This is my reasoning why:
(E) Until they are fully grown, horseshoe crabs shed their shells and grow new ones several times a year.
The passage states that "Surprisingly, inareas where tidal currents are very weak, juvenile horseshoe crabs are found not to have significant barnacle populations, even though they seldom burrow."

So, in E,the crab is mature and thus can shed its shell; but in the quoted above, the crab is just a kid, this mean it can not shed its shell. The choice turns out irrelevant, or at least can not explain the paradox (to me, of course). So I eliminated E.
IMO, If something can fill the gap between the quoted and E, states or implies, it is "juvenile crab is fully grown". Is it correct?

Could somebody point out the flaw in my reasoning? Thanks in advance.

Option E states that the juvenile crabs will have shedded its shells several times by the time it reaches its maturity.
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Re: In order to withstand tidal currents, juvenile horseshoe  [#permalink]

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02 Jul 2017, 08:42
first, test takers should have good vocabulary. Otherwise, test takers have to guess the relationships among 3 things: tide, barnacles and crabs.
=> B,D,E are left.
B intensifies the paradox => B is out
D is out because it does not explain why barnacle population is not significant, or low because crabs can still have large, (not very large) barnacle population.
E is correct even though E does not contain any word "weak tide"
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Re: In order to withstand tidal currents, juvenile horseshoe  [#permalink]

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03 Jul 2017, 08:30
Very interesting question and tricky as well
Imo E
The conclusion is about only juvenile horseshoe .
so only E is the valid answer.
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Re: In order to withstand tidal currents, juvenile horseshoe   [#permalink] 03 Jul 2017, 08:30

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