Spiny sea urchins could help solve a prickly problem in our oceans By The Seattle Times, adapted by Newsela staff Nov.

Transcription

1 Spiny sea urchins could help solve a prickly problem in our oceans By The Seattle Times, adapted by Newsela staff Nov. 19, :00 AM A sea urchin sits in a tank at the University of California, Santa Barbara marine science building where scientists are studying the creatures adaptation to ocean acidification. SANTA BARBARA, Calif. Scientist Gretchen Hofmann has a tank full of wriggly sea urchins. These purple, prickly animals live underwater and are not known for their speed. But sea urchins react very quickly to changes around them. So scientists are studying the urchins to learn how life under the sea will deal with big changes in the ocean. Humans burning coal, gas and oil have produced a gas called carbon dioxide. Carbon dioxide, also called CO2, is absorbed by the oceans and makes them more acidic. The water is changing faster than it has for millions of years. The rapid change is very dangerous for animals and fish that live under the waves. Sea urchins are very tough. Lots of animals are in danger of dying out. But urchins are in a very good position to live through the years ahead. They show how nature is amazing when it faces huge challenges. 1

2 An Experiment With Baby Urchins Hofmann works at the University of California and has studied urchins for many years. She said that sea animals can change very quickly. But she is worried that the harmful conditions in the ocean could push them too far. Which plants and animals can stay alive depends on many things. These include where they live and how many of them there are. Not everything will make it, and some plants or animals will die out forever. In the late 2000s, urchin fisherman Bruce Steele feared things were not going very well for the animals. He had good reasons to think so. Urchins graze on seaweed and are eaten by sea otters and humans. Steele is a scuba diver who has scooped up the animals from the seafloor since the 1970s. He sells the urchins to sushi restaurants. Steele heard about the sea getting more acidic. business and the ocean he loves. He saw right away what it could mean for his He contacted Hofmann. She started looking into his concerns. Her first experiment was putting baby urchins in water with lots of carbon dioxide. Hofmann then observed what happened. She found that the babies often got smaller in the water. The increased carbon dioxide stops the urchins from building up their shells and skeletons. Quickly Changing To Adapt Body size is very important to sea urchins. Bigger urchins can swim faster and get more food. But Hofmann also saw that not all of the babies had shrunk. Some didn t change size at all. Hofmann knew enough about science to know that this might be important. Animals can change to match their surroundings simply and quickly. In Manchester, England, a moth changed from mostly ivory color to black in just a few years. In Manchester two hundred years ago, there were lots of factories and the dirt from these buildings darkened the trees. There were two types of moth, one was ivory and the other was black. Most of the moths were white. But the ivory moths were very easy to see on the dark tree trunks. spotted and eaten by birds. These lighter insects were 2

3 Meanwhile, the black moths did well. So the most common color of the moth changed from ivory to black. Once the pollution was controlled, the tree trunks grew light again, and the number of ivory-colored moths increased. Like the moths, Hofmann thought that some urchins could handle the changes better than others. It all depends on the levels of CO2 in the water that the animals are used to. Near to the shore, for example, the water moves around a lot and the carbon dioxide levels change at different times of the day. Creating Tougher Sea Urchins The carbon dioxide levels are also higher or lower in different parts of the ocean. In Northern California and the Pacific Northwest, there is lots of CO2 in the water, so the urchins there are used to it. But in Southern California, the animals have experienced much less carbon dioxide. So Hofmann mated wimpy Southern California urchins with tougher males from the north. They created babies that were more resistant to the acidic water. The kids of that father were much better at maintaining the size of their body, Hofmann said. Researchers in Stanford grew urchins in Southern Californian water. They then compared these to animals in water from Oregon. They also found that some urchins had started to get used to higher levels of carbon dioxide. The urchins have shown they can match their bodies to the changing ocean. But the scientists still don t know how much the sea urchins can take. And the sea is continuing to fill up with carbon dioxide. The scientists also don t know how many urchins will shrink and die before they have adapted. 3

4 Quiz 1. What happened to the urchins when they were kept in water with high CO2 content? (a) They either got smaller or remained the same size. (b) Their shells became bigger. (c) They became huge. (d) They died. 2. According to the article, the survival of sea urchins may depend on: (a) the amount of fishing (b) the number of otters in the ocean (c) the effects of climate change on the ocean (d) the level of CO2 that the animals are used to 3. What happened once the pollution was controlled in Manchester? (a) The plants and trees became darker. (b) The number of black moths increased. (c) The number of white moths increased. (d) The number of white moths decreased. 4. Select the paragraph from the section, Creating Tougher Sea Urchins, that shows the second experiment Hoffman conducted. 4

5 Answer Key 1. What happened to the urchins when they were kept in water with high CO2 content? (a) They either got smaller or remained the same size. (b) Their shells became bigger. (c) They became huge. (d) They died. 2. According to the article, the survival of sea urchins may depend on: (a) the amount of fishing (b) the number of otters in the ocean (c) the effects of climate change on the ocean (d) the level of CO2 that the animals are used to 3. What happened once the pollution was controlled in Manchester? (a) The plants and trees became darker. (b) The number of black moths increased. (c) The number of white moths increased. (d) The number of white moths decreased. 4. Select the paragraph from the section, Creating Tougher Sea Urchins, that shows the second experiment Hoffman conducted. 20 So Hofmann mated wimpy Southern California urchins with tougher males from the north. They created babies that were more resistant to the acidic water. The kids of that father were much better at maintaining the size of their body, Hofmann said. 5