IELTS Forcast Reading Test 2026 - Q1 Test 5 with Practice Test, Answers And Explanation
Luyện tập đề IELTS Forcast Reading Test 2026 - Q1 Test 5 được lấy từ cuốn sách Forcast Test 2026 - Q1 với trải nghiệm thi IELTS trên máy và giải thích đáp án chi tiết bằng Linearthinking, kèm answer key và list từ vựng IELTS cần học trong bài đọc.
IELTS Forcast Reading Test 2026 - Q1 Test 5 with Practice Test, Answers And Explanation
Passage
❓ Câu hỏi passage 1
Question 1 - 6
The Reading Passage has six paragraphs A-F.
From the list of headings below choose the most suitable heading for each paragraph.
Write the appropriate numbers i-ix
List of Headings
I
Experimenting with an old idea
II
Life cycle of Madagascar spiders
III
Advances in the textile industry
IV
Resources needed to meet the project’s demands
V
The physical properties of spider silk
VI
A scientific analysis of spider silk
VII
A unique work of art
VIII
Importance of the silk textile market
IX
Difficulties of raising spiders in captivity
1
Paragraph A
2
Paragraph B
3
Paragraph C
4
Paragraph D
5
Paragraph E
6
Paragraph F
Question 7 - 10
Look at the following statements and the list of researchers below.
Match each statement with the correct researcher, A-C.
Write the correct letter, A-C.
List of Findings
A
Simon Peers
B
Nicholas Godley
C
Todd Blackledge
7
It takes a tremendous number of spiders to make a small amount of silk.
8
Scientists want to use the qualities of spider silk for medical purposes.
9
Scientists are making some progress in their efforts to manufacture spider silk.
10
Spider silk compares favourably to materials known for their strength.
Question 11 - 13
Choose ONE WORD ONLY from the passage for each answer.
Producing spider silk in the lab
Both scientists and manufacturers are interested in producing silk for many different purposes. Some researchers have tried to grow silk by introducing genetic material into and some animals. But these experiments have been somewhat disappointing. It is difficult to make spider silk in a lab setting because the silk comes from a liquid protein made in a inside the spider’s body. When a spider spins silk, it causes a that turns this liquid into solid silk. Scientists cannot replicate this yet.
Passage
❓ Câu hỏi passage 2
Question 14 - 19
The Reading Passage has six paragraphs A-F.
From the list of headings below choose the most suitable heading for each paragraph.
Write the appropriate numbers i-vii
List of Headings
I
Comparing two planets
II
A surprisingly small moon
III
A longstanding puzzle
IV
Saturn’s fascinating moon
V
The importance of Titan's gravity
VI
Expectations of possible solutions
VII
The problems for life on Titan
VIII
An advantage of the low temperatures
14
Paragraph A
15
Paragraph B
16
Paragraph C
17
Paragraph D
18
Paragraph E
19
Paragraph F
Question 20 - 23
Choose the correct letter, A, B, C or D.
Write the correct letter in boxes on your answer sheet.
20
Galileo's observations of Saturn were influenced by
A
the frequency of his attempts.
B
the quality of his equipment.
C
what he expected to see.
D
observations made by others.
21
The writer suggests that scientists are interested in Titan because
A
it is larger than Earth, although less dense.
B
its atmosphere may contain oxygen.
C
its surface is invisible because of a thick, colored fog.
D
its atmosphere has similar elements to Earth's atmosphere.
22
The writer uses the phrase "no walk in the park" because life forms on Titan would
A
probably exist in water.
B
be less developed than life forms on Earth.
C
face considerable difficulties.
D
be unable to move around.
23
How does the writer compare Saturn and Jupiter?
A
Saturn gives off more heat than Jupiter.
B
Jupiter is less dense than Saturn.
C
Saturn is less colorful than Jupiter.
D
Jupiter has more violent storms than Saturn.
Question 24 - 26
Choose NO MORE THAN TWO WORDS from the passage for each answer.
The Cassini-Huygens Probe
The Cassini-Huygens probe has produced clearer of Saturn. However, it may take up to before all the data from the probe has been analysed. It is expected that this data will assist in the investigation of the way function, and the nature of other planets and stars.
Passage
❓ Câu hỏi passage 3
Question 27 - 32
Choose the correct letter, A, B, C or D.
Write the correct letter in boxes on your answer sheet.
27
Why is it difficult to find mite harvestmen?
A
They are too small to see with the naked eye.
B
They can easily be confused with daddy longlegs.
C
They are hard to distinguish from their surroundings.
D
They do not exist in large numbers in any one place.
28
Why are mite harvestmen of interest to Dr Giribet and his colleagues?
A
They have been studied far less than most other species.
B
They show the effects of climate on the evolution of animals.
C
They have an unusual relationship with plants and other animals.
D
They provide evidence relating to a field of study other than insects.
29
What factor contributed to Wegener’s idea that present-day continents used to form a single landmass?
A
Changes in the level of the ocean
B
The distance that species could travel
C
The lack of certain fossils on one side of the Atlantic
D
Similarities in living conditions on both sides of the Atlantic
30
What point is made by the reference to armadillos?
A
Regions have both separated and become connected.
B
Certain animals could travel longer distances than others.
C
The oldest species of animals are likely to be found in Africa.
D
There is a tendency for animals to spread in a particular direction.
31
Which of the following is stated in the fifth paragraph?
A
Hawaii is a habitat that cannot support large birds.
B
Hawaii is an attractive habitat for certain species of birds.
C
Flightless birds are more likely to become extinct than others.
D
The Hawaiian goose became flightless after it had reached Hawaii.
32
Why is evidence from cockroaches of limited value?
A
They spread too fast.
B
They multiply too quickly.
C
They are found in too few places.
D
They have divided into too many species.
Question 33 - 36
Do the following statements agree with the information given in Reading Passage?
In following statements below, choose
YES if the statement agrees with the information
NO if the statement contradicts the information
NOT GIVEN if it is impossible to say what the writer thinks about this
33
The colonization of Hawaii by geese provides evidence of continental drift.
34
The reason why mite harvestmen don't exist on Hawaii can be explained.
35
The DNA of certain species has evolved more quickly than that of others.
36
Dr Boyer’s theory concerning the origins of Florida is widely accepted.
Question 37 - 40
Complete the summary using the list of words, A-I, below.
Write the correct letter, A-I, in boxes on your answer sheet.
The age and evolution of mite harvestmen
Some of the first creatures to live on land were the of mite harvestmen. Boyer, Giribet and others study differences in the of these insects, and trace the development of a number of of the species.
Their evolution appears to reflect changes in the location of . For example, the same type of mite harvestman is found in places that are now far apart but used to form Gondwana, part of a huge landmass.
A
branches
B
fossils
C
drift
D
DNA
E
evolution
F
Pangea
G
dispersal
H
ancestors
I
continents
DOL IELTS Đình Lực
05/05/2026
📖 Bài đọc passage 1
A unique golden textile
A two-man project to use spider silk is achieved after 4 years
A
A. A rare textile made from the silk of more than a million wild spiders has gone on display at the American Museum of Natural History in New York City. To produce the golden cloth, 70 people spent four years collecting golden orb spiders from telephone poles in Madagascar, while another dozen workers carefully extracted about 24 meters of thread from each of the arachnids. The resulting 11-foot by 4-foot textile is the only large piece of cloth made from natural spider silk existing in the world today.
B
B.
Spider silk is very elastic and strong compared with steel or Kevlar, said textile expert Simon Peers, who led the project. Kevlar is a lightweight synthetic fabric which is often compared to nylon. It is very tough and durable and used in bullet-proof vests. Spider silk is resistant to wear, tear, and heat and has absolutely no melting point. But the tensile strength of spider silk is even greater than Kevlar’s and maintains elasticity, a strand of high-grade steel. Most importantly, spider silk is extremely lightweight: a strand of spider silk long enough to circle the Earth would weigh less than 500 grams (18 oz). It is also especially ductile, able to stretch up to 140 percent of its length without breaking, and can hold its strength below -40°C. This gives it a very high toughness, which equals that of commercial fibers.
C
Researchers have long been intrigued by the unique properties of spider silk. Unfortunately, spider silk is extremely hard to mass produce. Unlike silkworms, which are easy to raise in captivity, spiders have a habit of chomping off each other’s heads when housed together. According to Peers, there’s scientific research going on all over the world right now trying to replicate the tensile properties of spider silk to apply it to all sorts of areas in medicine and industries, but no one has yet succeeded in replicating 100 percent of the properties of natural spider silk.
D
Peers came up with the idea of weaving spider silk after learning about the French missionary Jacob Paul Camboué, who worked with spiders in Madagascar during the 1890s and 1900s. Camboué built a small, hand-driven machine to extract silk from up to 24 spiders at once, without harming them. The spiders were temporarily restrained, their silk extracted, and then let go. Peers managed to build a replica of this 24-spider silk-spinning machine. It was used at the turn of the century, said Nicholas Godley, who co-led the project with Peers. As an experiment, the pair collected and restrained about 80 spiders. When we stuck them in the machine and started turning it, a lot of them started to spin beautiful gold-colored silk straight onto our machine, Godley said.
E
But to make even the tiniest significant size, the silk experts had to drastically scale their plan. Fourteen thousand spiders yield about an ounce of silk, Godley said, and the textile weighs about 2.8 pounds. The numbers are overwhelming. To achieve their goal, Godley and Peers began hiring dozens of spider handlers to collect wild arachnids and carefully harness them to the silk extractors. When they needed people who were willing to work with spiders, Godley said, because by the end of the project, the team had spent more than 1 million spider lifetimes. In return, they produced a beautiful yet absolutely impractical cloth, passion provided by love and obsession. Once the spiders had been silked, they were released back into the wild, said Godley. Godley said it takes them about a week to regenerate their silk. We can go back and get more from the same spiders, he said. It’s like the gift that never stops giving.
F
Of course, spending four years to produce a single textile of spider silk isn’t very practical for scientists trying to study the properties of spider silk, or companies that want to manufacture the fabric for use as a biomedical product, or an alternative to Kevlar armor. Several groups have tried inserting spider genes into bacteria or even cows and goats to produce silk, but so far, the attempts have been only moderately successful. Part of the reason it’s so hard to generate spider silk in the lab is that it starts out as a liquid protein that’s produced by a special gland in the spider’s abdomen. Using their spinneret, spiders apply force to rearrange the protein’s molecular structure and transform it into solid silk. When we talk about a spider spinning silk, we’re talking about how the spider applies force to produce a transformation from liquid to solid, said spider silk expert Todd Blackledge of the University of Akron, Ohio, US, who was not involved in creating the textile. Scientists simply can’t replicate the efficiency with which a spider produces silk. Every year we’re getting closer and closer to being able to mass-produce it, but we’re not there yet. For now, it seems we’ll have to be content with one incredibly beautiful cloth, graciously provided by more than a million spiders.
🔥 Đáp án & giải thích 1
1
VII
Giải thích chi tiết
Ứng dụng Linearthinking để giải quyết dạng Matching Headings
Step 01: Read relevant information to understand
Dựa vào phần Simplify & Connection ở trên, có thể suy ra:
→ Đại ý toàn đoạn: Giới thiệu một tấm vải vàng dệt từ tơ hơn một triệu con nhện – tác phẩm độc nhất vô nhị được trưng bày sau bốn năm lao động kỳ công.
----------------
Step 02: Compare meaning with meaning 📌 Đại ý của đoạn: Mô tả một tác phẩm duy nhất, mang tính nghệ thuật đặc biệt (vừa “rare”, vừa “only one”).
Chọn đáp án đúng: G. A unique work of art
Giải thích: đoạn nhấn mạnh sự độc nhất và giá trị trưng bày của tấm vải, phù hợp với “unique work of art”.
Lưu ý: Nếu chỉ scan từ khóa “spiders”, “collecting”, “silk”, người đọc dễ nhầm sang D (Resources needed …) hoặc E (physical properties), nhưng cả hai không tóm được ý chính “tác phẩm độc nhất” của đoạn.
A. In 1610 the Italian astronomer Galileo pointed his crude telescope at the planet Saturn and was dumbfounded by what he saw: "The planet Saturn is not alone, but is composed of three, which almost touch each other, and never move or change with respect to one another." Even more surprising, the two bulging planets on either side of the main planet had disappeared when he looked again a few months later. Eventually, the frustrated Galileo decided never to look at Saturn again. Now, of course, we have much better telescopes, and we know that Galileo was looking at the planet's unique set of wide, thin rings. Seen broadside, they resembled companion planets through Galileo's weak lenses; later, seen edge-on, they shrank to nothingness. But nearly 500 years after Galileo's observations, Saturn still teases astronomers. Saturn's magnificent rings, for example, consist of trillions of pieces of ice, some no bigger than a speck of dust. The ring particles are so small that they could be expected to scatter and fall into the planet, yet they are still there. Scientists are unsure about the origin of the rings, their exact chemical composition, and why they behave in the way that they do.
B
However, as spectacular as Saturn's rings are, the fuzzy orange ball of Saturn's giant moon Titan is even more interesting. Although it is larger than the planet Mercury, Titan probably resembles other large moons in the Solar System. It is a rock covered with ice and dirt. However, it has something no other moon has: a substantial atmosphere whose pressure is 50% greater than Earth's. Even more intriguing, Titan's atmosphere consists mainly of nitrogen (the primary component of our own air), mixed with carbon-based compounds. Cloaked in this atmosphere, Titan's surface may resemble the surface chemistry of the early Earth, but astronomers cannot see through the moon's maddeningly opaque orange fog.
C
All sorts of Earth-like chemical interactions could happen on Titan. Scientists hesitate to speak of the possibility of life when they speak of Titan, but it is a distant possibility. Living on Titan would be no walk in the park. From the vantage point of the Saturn system, the sun is a rather dim bulb. Titan is therefore a very cold place. Surface temperatures average about -300 degrees Fahrenheit. At those temperatures, water is a rock and would flow only from volcanoes. Although Titan is half water, there is nowhere to get a drink. In addition, there is no oxygen in Titan's atmosphere-it is all locked up in water ice. The only hope for life as we know it, and it is an exceedingly slim one, is that water mixed with ammonia may get warm enough deep below the surface to liquefy. If so, life could possibly eke out an underground living much like the hardy microbes that surround Earth's hydrothermal vents (deep cracks on the seabed through which boiling water and hot gases escape).
D
Titan could contain information on the prebiotic chemistry that led to life on Earth and perhaps elsewhere in the Universe. The bitterly cold temperatures that make Titan so forbidding for life in some ways make it more intriguing. Titan's chilly climate keeps things in a state of preservation, so that it can hang on to most of the substances that it has acquired during its 4.5 billion years in the Solar System. The organic reactions that may have established the starting conditions for life on the early Earth are long gone, erased by our planet's high-speed chemical and geologic evolution. On Titan, similar reactions may still be sitting in deep storage.
E
Measured against its showy rings and haze-obscured moon, Saturn itself seems dowmight ordinary. Yet the 75,000-mile-wide planet-the second largest in the Solar System-holds some serious interest of its own. Like the planet Jupiter, Saturn is a gas giant: a relatively small ball of rock surrounded by a vast envelope of helium, hydrogen, and various hydrogen compounds. Saturn is only half as dense as Jupiter, even less dense than water. It releases less heat than Jupiter, but, given its smaller size, scientists are not sure why it radiates any heat at all. Saturn's storms are, surprisingly, more powerful than Jupiter's, and its jet streams are much faster. The planet looks blander, however, because a thick haze of ammonia crystals obscures the colorful banding seen so easily on Jupiter.
F
Scientists hope that studying these differences will reveal how giant planets form, how weather systems work under different conditions, and what planets around other stars might be like. A recent spacecraft that investigated Saturn and Titan (the Cassini-Huygens probe) has produced results that Galileo would have dearly appreciated back in 1610: photographs that finally show Saturn with crystalline clarity. After all the data from Cassini-Huygens has been interpreted, even though that might take 40 years, all questions on these topics may have been answered once and for all.
🔥 Đáp án & giải thích 2
14
III
Giải thích chi tiết
Ứng dụng Linearthinking để giải quyết dạng bài Matching Headings
Step 01: Read to understand main idea
Dựa trên các câu đã simplified, ta thấy toàn đoạn tập trung vào:
Những quan sát sai lầm ban đầu của Galileo → khởi đầu cho một bí ẩn thiên văn lâu đời.
Đến nay, dù công nghệ đã tiến bộ, con người vẫn chưa hoàn toàn hiểu được nguồn gốc và hành vi của các vành đai sao Thổ.
⇒ Chủ đề trọng tâm: hiện tượng sao Thổ và những vành đai của nó vẫn là một bí ẩn kéo dài hàng trăm năm.
------------------
Step 02: Compare meaning with meaning
Đại ý của đoạn: Mở đầu bằng phát hiện gây bối rối của Galileo về sao Thổ, và kết thúc bằng việc các nhà khoa học hiện đại vẫn chưa thể lý giải hết những điều bí ẩn quanh hành tinh này.
Đáp án đúng phải thể hiện ý “một câu hỏi chưa có lời giải suốt nhiều thế kỷ.”
Few people have heard of the mite harvestman, and fewer still would recognize it at close range. The insect is a relative of the far more familiar daddy longlegs. But its legs are stubby rather than long, and its body is only as big as a sesame seed. To find mite harvestmen, scientists go to dark, humid forests and sift through the leaf litter. The animals respond by turning motionless, making them impossible for even a trained eye to pick out.’ They look like grains of dirt.’ said Gonzalo Giribet, an invertebrate biologist at Harvard University.
Dr Giribet and his colleagues have spent six years searching for mite harvestmen on five continents. The animals have an extraordinary story to tell - they carry a record of hundreds of millions of years of geological history, chronicling the journeys that continents have made around the Earth. The Earth’s landmasses have slowly collided and broken apart again several times, carrying animals and plants with them. These species have provided clues to the continents’ paths.
The notion of continental drift originally came from such clues. In 1911, the German scientist Alfred Wegener was struck by the fact that fossils of similar animals and plants could be found on either side of the Atlantic. The ocean was too big for the species to have traveled across it on their own. Wegener speculated correctly, as it turned out that the surrounding continents had originally been welded together in a single landmass, which he called Pangea.
Continental drift, or plate tectonics as it is scientifically known, helped move species around the world. Armadillos and their relatives are found in South America and Africa today because their ancestors evolved when the continents were joined. When South America and North America connected a few million years ago, armadillos spread north, too.
Biogeographers can learn clues about continental drift by comparing related species. However, they must also recognize cases where species have spread for other reasons, such as by crossing great stretches of water. The island of Hawaii, for example, was home to a giant flightless goose that has become extinct. Studies on DNA extracted from its bones show that it evolved from the Canada goose. Having colonized Hawaii, it branched off from that species, losing its ability to fly. This evolution occurred half a million years ago, when geologists estimate that Hawaii emerged from the Pacific.
When species jump around the planet, their histories blur. It is difficult to say much about where cockroaches evolved, for example, because they can move quickly from continent to continent. This process, known as dispersal, limits many studies. ‘Most of them tend to concentrate on particular parts of the world.' Dr Giribet said. I wanted to find a new system for studying biogeography on a global scale.
Dr Giribet realized that mite harvestmen might be that system. The 5,000 or so mite harvestmen species can be found on every continent except Antarctica. Unlike creatures found around the world like cockroaches, mite harvestmen cannot disperse well. The typical harvestman species has a range of fewer than 50 miles. Harvestmen are not found on young islands like Hawaii, as these types of islands emerged long after the break-up of Pangea.
According to Assistant Professor Sarah Boyer, a former student of Dr Giribet. ‘It’s really hard to find a group of species that is distributed all over the world but that also doesn’t disperse very far.'
What mite harvestmen lack in mobility, they make up in age. Their ancestors were among the first land animals, and fossils of daddy longlegs have been found in 400 million-year-ago rocks. Mite harvestmen evolved long before Pangea broke up and have been carried along by continental drift ever since they’ve managed to get themselves around the world only because they’ve been around for hundreds of millions of years, Dr Boyer said. Dr Boyer, Dr Giribet and their colleagues have gathered thousands of mite harvestmen from around the world, from which they extracted DNA. Variations in the genes helped the scientists build an evolutionary tree. By calculating how quickly the DNA mutated, the scientists could estimate when lineages branched off. They then compared the harvestmen's evolution to the movements of the continents. ‘The patterns are remarkably clear.’ Dr Boyer said.
The scientists found that they could trace mite harvestmen from their ancestors on Pangea. One lineage includes species in Chile South Africa, Sri Lanka and other places separated by thousands of miles of ocean. But 150 million years ago, all those sites were in Gondwana which was a region of Pangea.
The harvestmen preserve smaller patterns of continental drift, as well as bigger ones. After analyzing the DNA of a Florida harvestman, Metasiro americanus, the scientists were surprised to find that it was not related to other North American species. Its closet relatives live in West Africa. Dr Boyer then began investigating the geological history of Florida and found recent research to explain the mystery. Florida started out welded to West Africa near Segenal. North America than collied into them Pangea was forming. About 170 million years ago, North America ripped away from West Africa, taking Florida with it. The African ancestors of Florida’s harvestmen came along the ride.
Dr Giribet now hopes to study dozens or even hundreds of species, to find clues about plate tectonics that a single animal could not show.
🔥 Đáp án & giải thích 3
27
C
Giải thích chi tiết
☺️ Ứng dụng Linearthinking để giải quyết dạng bài Multiple Choice
Step 01: Read the question to understand
Simplified: Why is it difficult to find mite harvestmen?
Main idea: Cần tìm nguyên nhân chính khiến mite harvestmen (mạt/ nhện vụ mùa)khó được nhìn thấy hoặc phát hiện trong môi trường sống.
-------
Step 02: Locate relevant information
🔍 Từ khóa: “mite harvestmen”, “find", "difficult”
-> Dựa vào các từ khoá ở trên, có thể tìm được trích dẫn ở đoạn 1.
-------
Step 03: Read relevant information to understand
📌 Trích dẫn: “To find mite harvestmen, scientists go to dark, humid forests and sift through the leaf litter. The animals respond by turning motionless, making them impossible for even a trained eye to pick out. ‘They look like grains of dirt,’ said Gonzalo Giribet.” (Đoạn 1)
Simplified: Scientists go to dark, humid forests to find mite harvestmen
→ Kết quả: The animals turn motionless , making them impossible to pick out
Theylook like grains of dirt
Main idea: Khi bị làm phiền, mite harvestmen bất động hoàn toàn và trông như những hạt bụi → khiến các nhà khoa học rất khó nhận ra chúng giữa môi trường xung quanh.
-------
Step 04: Compare meaning with meaning
❌ A. They are too small to see with the naked eye.
→ Sai. Bài nói rằng chúng nhỏ “as big as a sesame seed” (cỡ hạt mè) chứ không nói là quá nhỏ để nhìn thấy.
❌ B. They can easily be confused with daddy longlegs.
→ Sai. Bài có nói chúng là họ hàng với daddy longlegs, nhưng không hề đề cập việc bị nhầm lẫn.
✅ C. They are hard to distinguish from their surroundings.
→ Đúng. Phù hợp với chi tiết “they turn motionless, making them impossible for even a trained eye to pick out” và “they look like grains of dirt.”
→ Nghĩa: chúng hòa lẫn hoàn toàn với môi trường xung quanh, rất khó phân biệt.
❌ D. They do not exist in large numbers in any one place.
→ Sai. Không có thông tin nào trong bài nói rằng chúng hiếm hay phân bố thưa thớt.
Spider silk is very elastic and strong compared with steel or Kevlar, said textile expert Simon Peers, who led the project. Kevlar is a lightweight synthetic fabric which is often compared to nylon. It is very tough and durable and used in bullet-proof vests. Spider silk is resistant to wear, tear, and heat and has absolutely no melting point. But the tensile strength of spider silk is even greater than Kevlar’s and maintains elasticity, a strand of high-grade steel. Most importantly, spider silk is extremely lightweight: a strand of spider silk long enough to circle the Earth would weigh less than 500 grams (18 oz). It is also especially ductile, able to stretch up to 140 percent of its length without breaking, and can hold its strength below -40°C. This gives it a very high toughness, which equals that of commercial fibers.
C. Researchers have long been intrigued by the unique properties of spider silk. Unfortunately, spider silk is extremely hard to mass produce. Unlike silkworms, which are easy to raise in captivity, spiders have a habit of chomping off each other’s heads when housed together. According to Peers, there’s scientific research going on all over the world right now trying to replicate the tensile properties of spider silk to apply it to all sorts of areas in medicine and industries, but no one has yet succeeded in replicating 100 percent of the properties of natural spider silk.
D. Peers came up with the idea of weaving spider silk after learning about the French missionary Jacob Paul Camboué, who worked with spiders in Madagascar during the 1890s and 1900s. Camboué built a small, hand-driven machine to extract silk from up to 24 spiders at once, without harming them. The spiders were temporarily restrained, their silk extracted, and then let go. Peers managed to build a replica of this 24-spider silk-spinning machine. It was used at the turn of the century, said Nicholas Godley, who co-led the project with Peers. As an experiment, the pair collected and restrained about 80 spiders. When we stuck them in the machine and started turning it, a lot of them started to spin beautiful gold-colored silk straight onto our machine, Godley said.
E. But to make even the tiniest significant size, the silk experts had to drastically scale their plan. Fourteen thousand spiders yield about an ounce of silk, Godley said, and the textile weighs about 2.8 pounds. The numbers are overwhelming. To achieve their goal, Godley and Peers began hiring dozens of spider handlers to collect wild arachnids and carefully harness them to the silk extractors. When they needed people who were willing to work with spiders, Godley said, because by the end of the project, the team had spent more than 1 million spider lifetimes. In return, they produced a beautiful yet absolutely impractical cloth, passion provided by love and obsession. Once the spiders had been silked, they were released back into the wild, said Godley. Godley said it takes them about a week to regenerate their silk. We can go back and get more from the same spiders, he said. It’s like the gift that never stops giving.
F. Of course, spending four years to produce a single textile of spider silk isn’t very practical for scientists trying to study the properties of spider silk, or companies that want to manufacture the fabric for use as a biomedical product, or an alternative to Kevlar armor. Several groups have tried inserting spider genes into bacteria or even cows and goats to produce silk, but so far, the attempts have been only moderately successful. Part of the reason it’s so hard to generate spider silk in the lab is that it starts out as a liquid protein that’s produced by a special gland in the spider’s abdomen. Using their spinneret, spiders apply force to rearrange the protein’s molecular structure and transform it into solid silk. When we talk about a spider spinning silk, we’re talking about how the spider applies force to produce a transformation from liquid to solid, said spider silk expert Todd Blackledge of the University of Akron, Ohio, US, who was not involved in creating the textile. Scientists simply can’t replicate the efficiency with which a spider produces silk. Every year we’re getting closer and closer to being able to mass-produce it, but we’re not there yet. For now, it seems we’ll have to be content with one incredibly beautiful cloth, graciously provided by more than a million spiders.
B. However, as spectacular as Saturn's rings are, the fuzzy orange ball of Saturn's giant moon Titan is even more interesting. Although it is larger than the planet Mercury, Titan probably resembles other large moons in the Solar System. It is a rock covered with ice and dirt. However, it has something no other moon has: a substantial atmosphere whose pressure is 50% greater than Earth's. Even more intriguing, Titan's atmosphere consists mainly of nitrogen (the primary component of our own air), mixed with carbon-based compounds. Cloaked in this atmosphere, Titan's surface may resemble the surface chemistry of the early Earth, but astronomers cannot see through the moon's maddeningly opaque orange fog.
C. All sorts of Earth-like chemical interactions could happen on Titan. Scientists hesitate to speak of the possibility of life when they speak of Titan, but it is a distant possibility. Living on Titan would be no walk in the park. From the vantage point of the Saturn system, the sun is a rather dim bulb. Titan is therefore a very cold place. Surface temperatures average about -300 degrees Fahrenheit. At those temperatures, water is a rock and would flow only from volcanoes. Although Titan is half water, there is nowhere to get a drink. In addition, there is no oxygen in Titan's atmosphere-it is all locked up in water ice. The only hope for life as we know it, and it is an exceedingly slim one, is that water mixed with ammonia may get warm enough deep below the surface to liquefy. If so, life could possibly eke out an underground living much like the hardy microbes that surround Earth's hydrothermal vents (deep cracks on the seabed through which boiling water and hot gases escape).
D. Titan could contain information on the prebiotic chemistry that led to life on Earth and perhaps elsewhere in the Universe. The bitterly cold temperatures that make Titan so forbidding for life in some ways make it more intriguing. Titan's chilly climate keeps things in a state of preservation, so that it can hang on to most of the substances that it has acquired during its 4.5 billion years in the Solar System. The organic reactions that may have established the starting conditions for life on the early Earth are long gone, erased by our planet's high-speed chemical and geologic evolution. On Titan, similar reactions may still be sitting in deep storage.
E. Measured against its showy rings and haze-obscured moon, Saturn itself seems dowmight ordinary. Yet the 75,000-mile-wide planet-the second largest in the Solar System-holds some serious interest of its own. Like the planet Jupiter, Saturn is a gas giant: a relatively small ball of rock surrounded by a vast envelope of helium, hydrogen, and various hydrogen compounds. Saturn is only half as dense as Jupiter, even less dense than water. It releases less heat than Jupiter, but, given its smaller size, scientists are not sure why it radiates any heat at all. Saturn's storms are, surprisingly, more powerful than Jupiter's, and its jet streams are much faster. The planet looks blander, however, because a thick haze of ammonia crystals obscures the colorful banding seen so easily on Jupiter.
F. Scientists hope that studying these differences will reveal how giant planets form, how weather systems work under different conditions, and what planets around other stars might be like. A recent spacecraft that investigated Saturn and Titan (the Cassini-Huygens probe) has produced results that Galileo would have dearly appreciated back in 1610: photographs that finally show Saturn with crystalline clarity. After all the data from Cassini-Huygens has been interpreted, even though that might take 40 years, all questions on these topics may have been answered once and for all.
Few people have heard of the mite harvestman, and fewer still would recognize it at close range. The insect is a relative of the far more familiar daddy longlegs. But its legs are stubby rather than long, and its body is only as big as a sesame seed. To find mite harvestmen, scientists go to dark, humid forests and sift through the leaf litter. The animals respond by turning motionless, making them impossible for even a trained eye to pick out.’ They look like grains of dirt.’ said Gonzalo Giribet, an invertebrate biologist at Harvard University.
Dr Giribet and his colleagues have spent six years searching for mite harvestmen on five continents. The animals have an extraordinary story to tell - they carry a record of hundreds of millions of years of geological history, chronicling the journeys that continents have made around the Earth. The Earth’s landmasses have slowly collided and broken apart again several times, carrying animals and plants with them. These species have provided clues to the continents’ paths.
The notion of continental drift originally came from such clues. In 1911, the German scientist Alfred Wegener was struck by the fact that fossils of similar animals and plants could be found on either side of the Atlantic. The ocean was too big for the species to have traveled across it on their own. Wegener speculated correctly, as it turned out that the surrounding continents had originally been welded together in a single landmass, which he called Pangea.
Continental drift, or plate tectonics as it is scientifically known, helped move species around the world. Armadillos and their relatives are found in South America and Africa today because their ancestors evolved when the continents were joined. When South America and North America connected a few million years ago, armadillos spread north, too.
Biogeographers can learn clues about continental drift by comparing related species. However, they must also recognize cases where species have spread for other reasons, such as by crossing great stretches of water. The island of Hawaii, for example, was home to a giant flightless goose that has become extinct. Studies on DNA extracted from its bones show that it evolved from the Canada goose. Having colonized Hawaii, it branched off from that species, losing its ability to fly. This evolution occurred half a million years ago, when geologists estimate that Hawaii emerged from the Pacific.
When species jump around the planet, their histories blur. It is difficult to say much about where cockroaches evolved, for example, because they can move quickly from continent to continent. This process, known as dispersal, limits many studies. ‘Most of them tend to concentrate on particular parts of the world.' Dr Giribet said. I wanted to find a new system for studying biogeography on a global scale.
Dr Giribet realized that mite harvestmen might be that system. The 5,000 or so mite harvestmen species can be found on every continent except Antarctica. Unlike creatures found around the world like cockroaches, mite harvestmen cannot disperse well. The typical harvestman species has a range of fewer than 50 miles. Harvestmen are not found on young islands like Hawaii, as these types of islands emerged long after the break-up of Pangea.
According to Assistant Professor Sarah Boyer, a former student of Dr Giribet. ‘It’s really hard to find a group of species that is distributed all over the world but that also doesn’t disperse very far.'
What mite harvestmen lack in mobility, they make up in age. Their ancestors were among the first land animals, and fossils of daddy longlegs have been found in 400 million-year-ago rocks. Mite harvestmen evolved long before Pangea broke up and have been carried along by continental drift ever since they’ve managed to get themselves around the world only because they’ve been around for hundreds of millions of years, Dr Boyer said. Dr Boyer, Dr Giribet and their colleagues have gathered thousands of mite harvestmen from around the world, from which they extracted DNA. Variations in the genes helped the scientists build an evolutionary tree. By calculating how quickly the DNA mutated, the scientists could estimate when lineages branched off. They then compared the harvestmen's evolution to the movements of the continents. ‘The patterns are remarkably clear.’ Dr Boyer said.
The scientists found that they could trace mite harvestmen from their ancestors on Pangea. One lineage includes species in Chile South Africa, Sri Lanka and other places separated by thousands of miles of ocean. But 150 million years ago, all those sites were in Gondwana which was a region of Pangea.
The harvestmen preserve smaller patterns of continental drift, as well as bigger ones. After analyzing the DNA of a Florida harvestman, Metasiro americanus, the scientists were surprised to find that it was not related to other North American species. Its closet relatives live in West Africa. Dr Boyer then began investigating the geological history of Florida and found recent research to explain the mystery. Florida started out welded to West Africa near Segenal. North America than collied into them Pangea was forming. About 170 million years ago, North America ripped away from West Africa, taking Florida with it. The African ancestors of Florida’s harvestmen came along the ride.
Dr Giribet now hopes to study dozens or even hundreds of species, to find clues about plate tectonics that a single animal could not show.
Simplified: Scientists go to dark, humid forests to find mite harvestmen
