Actual Test 02 Part 1 Lecture - Marine Biology

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P: Remeber that the there are many different types of jellyfish,/ and,/ well, despite its name,/ it isn't exactly a fish./ It actually belongs to the phylum cnidaria, as do corals, sea anemones, sea sponges, and the like./ Jellyfish are really a type of plankton, not fish,/ which means they are, fore the most part, controlled by the currents of the ocean./ They are about 98% water./ They have no brain/ and no bones,/ and they even lack a heart./ The body of the jellyfish is gelatinous and therefore transparent,/ meaning you can see through it./ Its gelatinous body is one of its main defense mechanisms against its many predators/ because it makes the jellyfish transparet/ or nearly invisible in the water./ Pretty good protection device./ There's something else you need to know about the jellyfish in relation to its body./ It is what we call polymorphic./ If you break the word down,/ you'll get its meaning./ Can anyone tell me what polymorphic might mean?

A: Well,/ the poly means more than one,/ and morphic would be body or something like that,/ so polymorphic means more than one body.../ I think.

P: Good work./ That's exactly what it means,/ and, in the case of some types of jellyfish,/ it can exist as two different species in its lifetime:/ the polyp/ and the medusa./ The jellyfish really starts out simple as apolyp, a cylindrical body with a mouth./ This is the earliest form of its development./ With time, it may develop into the latter stage, called the medusa,/ which is basically a network of tentacles extending down from the polyp body./ Now, the medusa is the second type of defense mechanism for the jellyfish,/ but this isn't all./ When it feels threatened or under attack from predators, it uses its tentacles as a weapon./ Lining the external wall of each tentacle/ are cnidoblasts./ These are the poisonous stingers of the medusa./ By the way, have any of you ever been stung by a jellyfish at the beach?

B: I was when I was young./ I just remeber that it really burned.

P: Wel, yep, that was the poison from the jellyfish's nidoblasts./ You probably were just unfortunate enough to get in its way or run into it./ They don't attack, class./ Remember they float around for the most part and have no real locomotion at all./ They can use their tentacles for some propulsion,/ but they are used more fore direction and guidance./ Anyways, back to the cnidoblasts./ Besides stinging us at the beach now and then, they are really the jellyfish's second form of defense/ as well as a means of capturing food./ The poisonous stingers contain a neurotoxin, which paralyzes the prey,/ and then the tentacles are used to pull the prey into its mouth.

B: But, Professor Keyes, aren't some jellyfish a serious threat to humans?/ I mean,/ I read about a guy getting stung and dying in Australia or somewhere last year.

P: Good point./ And he's right, class./ There are some that can be fatal./ The most dangerous jellyfish to humans is the box jellyfish,/ also known as the Irukandji jellyfish./ It's the type that stung the unfortunate fellow down under last year./ Interestingly enough,/ they are only found in the waters off of Australia./ They like cooler water temperatures./ And, they are quite small, actually,/ about the size of a coin,/ and have four main tentacles extending away from the main polyp./ Their cnidoblasts are highly toxic/ and are even located on their main bodies./ Once a person is stung,/ symptoms such as cramps,/ nausea,/ and high blood pressure can occur./ Now, you might think that because of crmaps, the victim might drown./ This is unfounded./ Let's remembr though, class,/ that most of the stings of the box jelly do not prove to be fatal,/ especially if medical attention is sought quickly./ Actually, I believe most people who end up dying have some type of pre-existing medical condition.

A: Wow, that's kind of scary, Professor Keyes./ But/ what about the man o' war?/ Isn't that a kind of jellyfish, too?

P: Sure is./ Actually, the Portuguese man o' war is a specialized colony of different types of polyps,/ four to be exact,/ which kind of latch on to each other./ Each one is dependent on the other for survival./ It really is a miraculous organism./ It is highly developed for a jellyfish./ Most commonly, the man o' war is found in warm waters,/ especially off the east coast of the U.S./ The four types of polyps are for floatation,/ locomotion,/ digestion,/ and reproduction./ The pneumatophore is the polyp that controls floatation and depth./ Its color is usually blue or purple./ Sometimes, you can even see them floating up on the surface of the water/ with their many tentacles called dactylozooids floating underneath them.

예전보다 확실히 노트테이킹 스킬이 많이 늘었습니다.. 필요한 부분만 쓰는 능력이 생겼네요,,^^

123은 별 문제 없이 풀었습니다..

4는,, B하고 D가 헷갈렸는데,, D의 evolve가 잘못되었기에 B로 했습니다....

5번도 잘 했고요,, 근데,, 6번을 틀렸네요...^^

솔직히 아직도 잘 이해가 가지 않습니다...

해설에 의하면 '해파리는 폴립과 메두사의 두 가지 형태로 나중 단계로 자랄 수도 있다고 했으므로 모든 해파리가 두 번째 단계로 가는 것은 아니라는 것을 알 수 있다.'라고 쓰여 있는데,, 도통 무슨 뜻인지 모르겠습니다..

다시 듣고 스크립트를 봐도 왜 D가 답인지 이해가 가지 않습니다..

[디오리지날뉴아자speaKing쌤]

그런 경우는 독해를 하듯 해석하고...전체적 논리 전개를 이해해야 한다...특정 용어가 나와서 힘들게 하면, 좀더 쉬운쪽을 먼저 이해하고 나중것을 맞춰보는 노력도 필요하다...아직 고등학생이어서 다양한 책과 주제에 열려있지 않아서 그럴것이다..홧팅...

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네,,