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Bug of the Week: Cicada Nymph

A few weeks ago in Summer Sounds 1, we saw the adult cicada.

If you have cicadas around, you may have found some of these.

cicada exoskeleton

It is the dried “skin” or exoskeleton of the cicada nymph. Cicada nymphs spend a year or more underground feeding on tree roots. When they are ready to emerge as adults, they dig out of the ground, crawl up onto a tree or the side of a building, and shed their exoskeleton for the last time.

A few days ago we dug up something really cool in the garden.

cicada nymph

What is this weird grub? It is a live cicada nymph! Check out the white eyes. They were eerie.

It was really clumsy and kept rolling onto its back.

cicada nymph

On its back, it was easier to see the large front legs used for digging, with dark claws. In between the front legs is the tube mouth the cicada uses to suck on tree roots.

You can see those things in the shed exoskeleton as well.

cicada exoskeleton

Note:  if you have one of shells, examine it closely. In the back where the skin has split you can often see tiny white threads. Those are the reminants of the cicadas breathing tubes, called trachae.

After a few photos, the cicada nymph went back into the soil. Hopefully, it will be singing in the trees someday soon.

Edit: A friend posted a link to a cool video of a cicada molting. Thanks Molly!

Meet a Scientist Monday: Beach Science Edition

Do your kids love to go to the beach? Any want to become marine scientists or oceanographers (my fourth grade ambition)?

The Monterey Bay Aquarium has a whole section devoted to science careers related to marine science.

Ever hear of an aquarist? Do you know what they do?

Aquarists feed, monitor and otherwise care for aquatic animals in aquarium settings. In addition to keeping records, they may clean, disinfect, and/or monitor water quality of the tanks. A lucky few will get to design or build exhibits. Basically they do everything you do to keep your home aquarium going, they just do it at a much bigger scale. Check Bryan Banks profile to hear his experiences as an aquarist.

If your child is interested in art and science they might want to consider becoming an exhibit designer. Check Jody Armstrong Stebben’s profile to see what an exhibit designer does.

Who knows what a trip to the beach might lead to?

beach

Weekend Science Fun: Beach Science – Seawater

Is there a trip to the beach in your future this summer? Although trips to the beach are mostly pure fun, that doesn’t mean you can’t include a little science. Prepare for seashore science activities ahead of time and your children will have even more to discover when you get back home.

ocean

What do you usually see at the beach? Of course you’ll see sand, rocks and water. If you are lucky you may also spot some wildlife and algae. Over the next few weeks we are going to have a series of science discussions, experiments and activities on things you find at the seashore.

This week:  Seawater Science

It doesn’t take long at the beach to discover that seawater is salty. You can taste the spray on your lips. Ever wondered why seawater is salty or what is in it that makes it taste salty? There really is science in seawater.

1. Seawater pH

One easy experiment is to take along some pH paper and check how acid or basic seawater is. Compare it to other substances and to tap water.

Typically seawater is basic, that is higher than 7.0. Seawater pH is an important aspect of its chemistry because it impacts such processes as the laying down of calcium by corals.

2. Seawater salts

Gather:

  • Seawater
  • Plain water
  • 2 similar stainless steel or glass pans, or better yet, beakers
  • Heat source like a stove
  • Potholders

With the help of an adult, bring one cup of seawater in one pan and one cup of tap water in another pan to a boil. Turn down the heat and simmer until the water is almost dry. Watch carefully. Try not to let it boil completely dry because that will harm the metal of the pan. Remove from the heat and set in a warm place to finish evaporating away the water. What’s left?

Optional:  in a third pan place tap water and add a Tablespoon of salt. Boil as above. What happens when you evaporate the water in this case?

You should see a residue in the seawater pan. Pretend you are a chemist. How would you figure out what is in the residue?

One way is to do a flame test. When different chemicals are added to a flame, the resulting colors can give you information about what salts or elements are present. Here a trained chemistry teacher shows how this works.

Note: If you’d like to see how to do this, the book Fireworks by Vicki Cobb and Michael Gold (Photographer) has instructions for performing flame tests included as one of the activities. See Fireworks for the Fourth of July for a review.)

Using flame tests and other techniques, scientists have found over 70 elements in seawater.

How did those elements get into seawater? When I was young, I learned that the movement of freshwater over the earth’s crust picked up salts and carried them into the sea. Over time the salts built up because they are left behind when the water evaporates to move through the water cycle.

When I watched Going Deep on Scientific American Frontiers I found out that isn’t the only way salt gets in the ocean.

About thirty years ago, deep sea explorers found features known as hydrothermal vents along mid-ocean rifts. These are places on the ocean floor where seawater seeps into cracks in the crust. The water becomes extremely hot when it comes into contact with magma under the surface. It can’t boil, however, because of the extreme pressure at those depths. It dissolves some of the minerals from the crust and then flows back up into the ocean, carrying the dissolved minerals with it. Scientists have figured out that these vents are a significant source of the salts in the ocean.

A final process that provides salts to the oceans is the eruption of volcanoes under water. This is similar to the vents because the seawater is reacting with hot magma and lava, and dissolving some of the minerals in the liquid rocks.

Seawater is fascinating stuff and we still have a lot to learn about it.

Hope you have fun at the beach and watch out for those waves!

Resources:
(Affiliate links go to Amazon)

For the youngest set:

Hello Ocean by Pam Munoz Ryan and Mark Astrella (Illustrator)

For older kids:

The Magic School Bus on the Ocean Floor by Joanna Cole and Bruce Degen (Illustrator)

Blue Planet: Seas of Life DVD

Note: the linked page has some video clips.

For Adults:

A Scientist at the Seashore (Dover Science Books) by James S. Trefil

Edit: To check the rest of the posts on beach science, follow these links:

Sea Horses and Other Fish

Shore Birds

Tide Pool Invertebrates

Beach Science- Boats

Beach Science Algae

Beach Science-Sand

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