How to make a Naked Egg

A "naked egg" is an egg that has no shell. Let me say that again, an egg with no shell…

Read more →

Homemade Ice Cream

Making ice cream at home or in the classroom is easy. With just a few simple supplies you can squish up a batch in just about 15 minutes.

Read more →

Make a non-toxic lava lamp at home

This is one of our most popular do at home activities! With just a few items from your kitchen you can create a bubbling version of a lava lamp…

Read more →

How to make Slime

Here is our recipe for slime. This polymer goo is similar to flubber and just as much fun. Try making both to see how changing the amounts of ingredients can make a huge change in the end product.

Read more →

Page 1 of 512345

The post just a test appeared first on Science Cafe.

1. Eggshell – The outer eggshell is made almost entirely of calcium carbonate (CaCO3) and is covered with as many as 17,000 tiny pores. It is a semipermeable membrane, which allows air and moisture to pass through its pores. The shell also has a thin outermost coating called the bloom or cuticle that helps keep out bacteria and dust (see below 15).
2. Outer shell membrane
3. Inner shell membrane – These two membranes – outer and inner – are just inside the shell surrounding the albumen (white). The two membranes provide an efficient defense against bacterial invasion and are made partly of keratin. The outer membrane sticks to the egg shell while the inner membrane sticks to the albumen. When an egg is first laid, it is warm. As it cools, the contents contract and the inner shell membrane separates from the outer shell membrane to form the air cell (see 14 below).
4. Chalaza – are twisted in opposite directions and serve to keep the yolk centered. The more prominent the chalazae, the fresher the egg.
5. Exterior albumen (outer thin albumen) — The outer thin albumen is a narrow fluid layer next to the shell membrane.
6. Middle albumen (inner thick albumen) -The inner thick white (chalaziferous layer) is a dense, matted, fibrous capsule of albumen around the vitelline membrane of the yolk. The matted fibrous capsule terminates on each end in the chalazae, which are twisted in opposite directions and serve to keep the yolk centered. This part of the egg is a excellent source of riboflavin and protein. In high-quality eggs, the inner thick albumen stands higher and spreads less than thin white. In low-quality eggs, it appears thin white.
7. Vitelline membrane – The clear casing that encloses the egg yolk. When an egg is said to be “mottled”, the yolk surface is covered with many pale spots or blotches. The strength and integrity of the vitelline membrane are very important in preventing egg yolk mottling.
8. Nucleus of pander – a plug of whitish yolk, with no particular significance for development and whose function is purely a nutritive one, like the rest of the yolk. (See: Int. Schmitt S., (2005) J. Dev. Biol. 49: 1-8).
9. Germinal disk (blastoderm) – a small, circular, white spot (2-3 mm across) on the surface of the yolk; it is where the sperm enters the egg. The nucleus of the egg is in the blastodisc. The embryo develops from this disk, and gradually sends blood vessels into the yolk to use it for nutrition as the embryo develops.
10. Yellow yolk – a major source of vitamins, minerals, almost half of the protein, and all of the fat and cholesterol. The yolk contains less water and more protein than the white, some fat, and most of the vitamins and minerals of the egg. These include iron, vitamin A, vitamin D, phosphorus, calcium, thiamine, and riboflavin. The yolk is also a source of lecithin, an effective emulsifier. Yolk color ranges from just a hint of yellow to a magnificent deep orange, according to the feed and breed of the hen.
11. White yolk – Also known as, the latebra is an area of white yolk located in the center of the yolk. It is lower in fat and therefore stands out as a bright white area in many Magnetic Resonance Images. The specific function of the latebra is uncertain but it may act as a central structure around which the additional layers of the yolk are formed.
12. Internal albumen (Chalaziferous albumen)– The inner thick white (chalaziferous layer) is a dense, matted, fibrous capsule of albumen around the vitelline membrane of the yolk. The matted fibrous capsule terminates on each end in the chalazae, which are twisted in opposite directions and serve to keep the yolk centered.
13. Chalaza chalazae, which are twisted in opposite directions and serve to keep the yolk centered. The more prominent the chalazae, the fresher the egg. chalazae, which are twisted in opposite directions and serve to keep the yolk centered.
14. Air cell – An air space forms when the contents of the egg cool and contract after the egg is laid. The air cell usually rests between the outer and inner membranes at the eggs larger end. As the egg ages, moisture and carbon dioxide leave through the pores of the shell, air enters to replace them and the air cell becomes larger.
15. Cuticle or bloom – The shell is produced by the shell gland (uterus) of the oviduct, and has an outer coating, the bloom or cuticle. The cuticle somewhat seals the pores and is useful in reducing moisture losses and in preventing bacterial penetration of the egg shell. Most of cuticle is removed from table eggs when they are mechanically washed.

The post Anatomy of a chicken egg appeared first on Science Cafe.

The shell of an egg (typically a chicken egg) is made up of primarily calcium carbonate. If you soak this egg shell in vinegar (which is about 4% acetic acid), you start a chemical reaction that dissolves the calcium carbonate shell. The acetic acid reacts with the calcium carbonate in the egg shell and releases carbon dioxide gas that you see as bubbles on the shell.

CaCO₃ (s) + 2 HC₂H₃O₂ (aq)   →   Ca(C₂H₃O₂)₂ (aq) + H₂O (l) + CO₂ (g)

The egg insides remain intact and are held together by the two fragile membranes just inside the shell.

Here’s what you need

Let’s get to the fun stuff. In order to make a Naked Egg you will need the following items:

• Vinegar (at least 16 ounces)
• A couple of glasses or cups
• Raw eggs

The process is really very simple. Carefully place the egg in a cup and fill the cup with vinegar so that the egg is completely covered. Don’t worry if the egg floats a bit. Just get enough vinegar in the cup to mostly cover the egg.

An egg soaking in vinegar. The bubbles are carbon dioxide gas.

Now the hard part – you will have to wait as the acetic acid in the vinegar begins to react with the calcium in the egg shell. In just a short while, you should see some bubbles appearing on the outside of the egg. These are bubbles of carbon dioxide gas from the reaction. It can take 12-24 hours before a good portion of the shell is removed. A good sign of progress is a white frothy scummy layer on the top of the surface of the vinegar.

After a day of soaking you can carefully remove the egg from the vinegar. I would suggest pouring the liquid into another cup and catching the egg in your hand. Using a spoon to fish the egg out might seem like a good idea, but I’ve seen a few eggs break or get damaged when using a spoon to remove them.

At this point you may be able to literally rub the shell off the egg with your fingers. It will rub off as a white powdery substance. Give it try, just be very careful, you don’t want to break the egg, it’s getting more fragile as the shell is slowly dissolved. Depending on your particular egg, you may already have a naked egg. However, I would suggest you fill a cup with fresh vinegar and soak the egg for at least one more day.

After two days of soaking you should have a pretty cool Naked Egg. Notice that the egg is a bit bigger than when you first started. This is because some of the vinegar (and some of the  water in the vinegar) has moved through the membranes to the inside of the egg. The membranes are semi-permeable and allow water to move through them. This is called osmosis.

Fun things to do with your naked eggs

Naked eggs are cool, but experimenting with them is even cooler. You have probably already noticed that your naked egg is kind of rubbery. How far above the table can you drop your egg and have it survive by bouncing? I would suggest you start at one inch, then try two inches, and so on. Keep in mind that eventually this is going to get messy when it the membrane breaks. You might want to do this experiment outside.

If you want to see your egg get really big, simply put it in a cup filled with water. The makeup of the inside of the egg is around 90% water. If you put the egg in a cup of (100%) water, the water will begin to move inside the egg through the membrane to equalize the amount of water inside and outside of the egg membrane. This process of water moving through a membrane is called osmosis. Osmosis equalizes – or makes the concentration of water on both sides of the egg membrane the same. This means the egg will swell as the water moves inside and get larger.

You can even color the inside of your egg if you soak it in some water with food coloring. This is a nice way to verify that the water in the cup is really moving through the egg membrane and not just coloring the outside.

Shrink your Egg

A naked egg that was soaked in corn syrup for a few days. Much of the water inside the egg has moved out through the membrane.

Now that you know about osmosis, you might ask “can I make my egg shrink” or shrivel up? Of course, you just need a liquid that has only a little bit of water. A common substance you may have at home that fits this requirement is corn syrup.

Slip your Naked Egg into a cup filled with corn syrup and let it sit for a day, or two, or more and you will begin to see your egg begin to shrink and look sort of  baggy. Corn syrup has very little water content. Once inside the syrup, the water inside the egg begins to move across the semi-permeable egg membrane to equalize the water concentration. Again, that’s osmosis at work. If you leave your egg in the syrup long enough it will begin to look something like a huge raisin – with of course a yoke inside.

If you get tired of the shriveled egg look, you can reverse the process by just dunking the egg back in a cup of water. The water will once again move across the membrane and fill the egg with water again.

A big thank you to one of our visitors who grabbed a great photo of what happens when you soak a naked egg in corn syrup for a few days. I might call it a “dehydrated naked egg.” And side-by-side is a brilliant red naked egg soaked in red food coloring. Thank you Evers Ding for permission to use your photo and check out the rest of Evers egg photos on his blog.

Can I eat the Naked Egg?

Several visitors have posed the question, “Can I eat my naked egg?” I would NOT recommend eating a naked egg prepared this way. Keep in mind you created your egg by soaking a raw egg in vinegar sitting at room temperature for a few days. That is not how to treat eggs you are going to eat! Even if you stored the egg in the refrigerator, I still would not recommend eating the raw egg. Some have asked if you could store the egg in the fridge, then cook it and eat it. Well, I suppose you could, but given the amount of vinegar that probably moved past the membrane into the egg, it’s most likely not going to taste all that great. Instead of eating your naked egg, just experiment with it.

Look, if you are really interested in creating a Pickled Egg that you can eat, check out some of the recipes from the National Center for Home Food Preservation and for more information about safe egg handling practices check out the Egg Safety Center.

Does it Smell?

A naked egg soaked in food coloring on the right.

A few of you asked if the eggs will start to have that rotten egg odor after a while. Well, I think it depends on how you store the egg. That rotten egg odor comes from hydrogen sulfide. Eggs contains sulfur because it is needed for the production of feathers in the chicken.

I have not noticed any bad odors with my naked eggs. After dissolving the shell in the vinegar, I keep the egg in a glass of water for up to a week and have not noticed any odor when the egg does accidentally break. It would be an interesting (and probably stinky) experiment to leave an egg out for a week or two in order to give it a chance to start to decompose. I would suspect that as the contents start to decompose, sulfide compounds will begin to form and it will start to smell really bad.

Science Fair Project Ideas

In terms of doing a science fair project here are a couple variables you might want to explore in more detail. Just a list of ideas to get you thinking. If you come up with other ideas let me know!

References

I’ve received many requests from students doing science fair projects related to the Naked Egg looking for further or deeper references. I have included some print references below. You can use the World Library Catalog to locate one of these items in a library near you!

1. B. Z. Shakhashiri, Chemical Demonstrations: A Handbook for Teachers of Chemistry, Vol 3, p. 283-285, Wisconsin (1989).
2. B. Cocanour and A. S. Bruce, J. College Sci. Teach. 15:127 (1985)
3. V. L. Mullin, Chemistry Experiments for Children, Sterling Publishers: New York (1961).
4. L. A. Ford, Chemical Magic, T. S. Denison and Co.: Minneapolis, Minnesota (1959).

The post How to make a Naked Egg appeared first on Science Cafe.

The post test post appeared first on Science Cafe.

Don’t worry to much if you don’t have whole milk or heavy cream. Nearly any milk will work and you can substitute half-and-half for the cream. Ideally you want ingredients with a high fat content because these will create a creamy texture when cooled. Remember that we’re just experimenting here, so try what you have on hand!

Ingredients

• 1/2 cup milk (Whole or 2% work best)
• 1/2 cup heavy cream (optional)
• 1/2 teaspoon vanilla
• 1 tablespoon sugar
• 4 cups crushed ice
• 4 tablespoons salt
• 2 quart size plastic bags
• 1 gallon size plastic freezer bag
• a hand towel or gloves to keep fingers from freezing as well

Basic Directions

Begin with mixing the milk, vanilla and sugar together in one of the quart size bags. If you want, you can mix this in a bowl first so that you get all the sugar dissolved. Seal the bag tightly, you want to try to get as much of the air out of the bag as you can. Too much air left inside may force the bag open during the mixing stage.

Place this bag inside the other quart size bag, again leaving as little air inside as possible and sealing well. By double-bagging, the risk of salt and ice leaking into the ice cream is minimized.

Put the two bags inside the gallon size bag and fill the gallon sized bag with ice, then sprinkle salt on top. Again, squeeze out as much air as possible and then seal the bag. Wrap the bag in the towel or put your gloves on, and shake and massage the bag, making sure the ice surrounds the creamy mixture. Five to eight minutes should be enough time to allow the mixture to freeze into ice cream.

When you are all done carefully open the bags and extract your ice cream. Enjoy!

If you’d like to experiment a bit more you can try substituting a mixture of heavy cream and your choice of milk. Mix up a few different batches and compare the texture of ice cream. Which to you think will have a smoother texture?

We suggest using freezer bags because they are thicker and less likely to develop small holes, allowing the bags to leak. You can get away with using regular plastic bags for the smaller quart sizes, because you are double-bagging. If you plan to do this indoors, we strongly recommend using gallon size freezer bags.

What does the salt do?

Salt forces the ice surrounding the bag of ingredients to melt. This “brine” solution or liquid that forms in the gallon bag absorbs the heat from the ice cream mix and gradually lowers the temperature of the mix until it begins to freeze.

If there were no salt added to the ice, it would melt at 32 degrees Fahrenheit and eventually the ice water and mix would come to equilibrium at 32 degrees. The ice cream mix, however, does not begin to freeze until its temperature falls below 27 degrees. Therefore, in order to freeze the mix, we need to add salt to the ice to lower the freezing temperature.

With 4 tablespoons of salt mixed with our ice, the brine temperature should remain constant at around 8 to 12 degrees Fahrenheit. This will give the rapid cooling and freezing that is essential to making smooth creamy ice cream.

The post Homemade Ice Cream appeared first on Science Cafe.

Start by cleaning out the bottle and filling it with about 2 inches of water. Now pour in the vegetable oil to nearly the top. In order to color your lava, you will need to add several drops of food coloring. Notice that the food coloring does not mix or color the oil as the drops sink.

Materials:

• Plastic bottle (any size)
• Vegetable Oil
• Water
• Effervescing antacid tablet
• Food Coloring

What to do:

1. Fill the plastic bottle with 2 inches of water.
2. Fill the rest of the way with vegetable oil.
3. Put in 5 or 6 drops of food coloring.
4. Drop in an effervescing antacid tablet and you just made your very own lava lamp.
5. Try putting a flashlight under the bottle see what the lava lamp looks like now!

What is the Science?
Oil will not mix with water it is an example of a hydrophobic molecule. The term hydrophobic literally means water fearing from the Greek language hydros “water” and phobos “fear”. Food coloring is a hydrophilic molecule. The term hydrophilic literally means water loving from the Greek language hydros “water” and philic “friendship”. The food coloring has the ability to mix or transiently bond with the water (H2O) through hydrogen bonding. When you place the effervescing antacid tablet into the bottle it will dissolve in the water and form bubbles of carbon dioxide gas. The gas rises and takes some of the colored water along with it to the surface of the oil. When all of the gas has escaped out of the top of the bottle the water droplet falls back to the bottom of the bottle.

The post Make a non-toxic lava lamp at home appeared first on Science Cafe.

What you need:

• 1 cup hot water
• 1.5 tsp. Borax (non-toxic/available by laundry detergents)
• 2 cups clear glue
• 2 cups warm water
• 1 tsp. liquid watercolor

What to do:

1. Mix 1 cup hot water and 1.5 tsp. of Borax until dissolved. Set aside.
2. Mix 2 cups of clear glue and 2 cups of warm water together in a plastic bowl.
3. Using a metal spoon, slowly pour Borax mixture into the glue mixture while stirring quickly. Stir until the mixture leaves the side of the bowl. Slime will be sticky. Knead the mixture until it is no longer sticky. The more you work with it the easier it will become.

What’s the science?

Slime is an excellent example of a polymer. Polymers are large molecules consisting of repeating identical structural units connected by covalent chemical bonds. Polymers can be naturally occurring or manmade. Manmade polymers are materials like nylon, polyester, and polystyrene. Examples of naturally occurring polymers are proteins in our body like tubulin and actin. These proteins make up microtubules and microfilaments that serve as structural components within our cells.

Storage and Safety Guidelines:
Store Slime in an airtight container for about 3 weeks of use. Slime is non-edible. When you are through with it, discard in a trash container. Do not wash down the drain.

More about Slime:

Slime is a polymer. Polymer is a term used to describe anything that consists of repeating identical structural units. It basically is like a long strand of spaghetti and the long chains flow past each other with ease. They can be naturally occurring or man-made (synthetic). Examples of polymers include plastics, starches, sodium polyacrylate, nylon and many more. Slime is also considered to be a non-Newtonian Fluid, basically a fluid that has special properties.

You should answer the following questions when exploring the properties of slime (a.k.a. playing with the cool stuff). Make sure your record your observations and post them in the comment box below. Try and do this before you read the rest of the article.

1. Describe how the slime reacts when you pull it apart with a quick forceful motion?
2. Describe how the slime reacts when you let it drip between your fingers?
3. Can you form a ball? What happens when you drop it on the table?
4. Do other fluids (like water, or ketchup) act the same way?

History of Slime:

Slime as a toy dates back to the 1920′s, when chemist Hermann Staudinger was researching polymers. He was the first one to try and make long cross-linked chains of the molecules instead of circles. This allowed the polymer to be slippery and gooey. By the 1930′s other scientists used his polymer model and synthetic polymers began to be studied and created. But it wasn’t until the 1980′s that slime began to be sold in stores as a toy for children. Ever since then you can’t step into a toy store without seeing the gooey, oozy stuff on the shelves. The slime you find in the store and the slime you can make with this recipe are both non-Newtonian fluids. Did you try to make it and answer the questions about its properties? If so, read on to find out about non-Newtonian fluids.

What does non-Newtonian mean?

All fluids have a property known as viscosity that describes how the fluid flows – commonly thought of as how thick or thin a fluid is. For instance, honey is much more viscous than water. When a fluid’s viscosity is constant it is referred to as a Newtonian fluid. Slime is an example of a fluid whose viscosity is not constant, it changes depending on the stress or forces applied to it. If you pull it apart real hard and apply a large force, it becomes very viscous and will break in half. If you gently pour it, applying little force, it will flow like honey or molasses. This kind of fluid is called a dilatant material or a shear thickening fluid. It becomes more viscous when agitated or compressed.

Another non-Newtonian liquid is ketchup. Ketchup behaves in just the opposite way from Slime. It becomes less viscous when agitated. Liquids like this are called thixotropic. If you leave a bottle of Ketchup on a shelf, it becomes thicker or more viscous. Nearly everyone has experienced this while trying to pour the liquid from a new bottle – it refuses to move. If you shake the bottle or stir it up it becomes less viscous and pours easily. Another example of a non-Newtonian fluid is Oobleck, one of our other great activities.

Is the slime in the store made using this recipe?

Most commercially sold slime is made using polyvinyl alcohol (PVA), a non-toxic substance that gives slime its texture. PVA still needs to be mixed with borax to get the final slime product. The borax is a gelling agent that cross links the PVA molecules together to form the slime. Borax does the same thing with the glue in this recipe. You can find Borax in the laundry detergent aisle in your grocery store. It is an inexpensive laundry booster and has lots of great household uses.

Other sources about slime:

There are some fun books that discuss animals in nature that produce their own slime, science experiments and other fun facts. You can find these and many other books at your local library.

• The Book of Slime by Ellen Jackson
• Lotions, Potions and Slime: Mudpies and More! by Nancy Blakey
• Oobleck, Slime & Dancing Spaghetti: Twenty Terrific at Home Science Experiments Inspired by Favorite Children’s Books by Jennifer Williams

Make sure you try this at home and don’t forget to come back and write a comment about how it went.

The post How to make Slime appeared first on Science Cafe.

What you need:

• Bar of Ivory™ Soap and another brand of soap
• Paper towel
• Microwave oven
• Bowl of water

HAVE AN ADULT HELP WITH THIS EXPERIMENT!

What to do:

1. Drop the bars of soap into the bowl of water. Notice how one floats and one doesn’t.
2. Remove the Ivory soap from the water. Break it in half and notice if there are any air pockets.
3. Place the Ivory soap in the middle of a paper towel and place in a microwave on HIGH for 2 minutes.
4. Observe what happens to the soap! Don’t over cook your soap soufflé! Allow your soap to cool for a minute before touching it.

What’s the science?
Ivory soap floats because it has air pumped into it while it is being made. It also contains water, both in the form of water vapor trapped in air bubbles and water in the soap matrix itself. The heating of the water that is inside the soap causes the expanding effect. As the water vaporizes, air bubbles are formed. The heat causes trapped air to expand and the soap to soften and become pliable.

This is an example of Charles’ Law which states that as the temperature of a gas increases so does its volume. When the soap is heated, the molecules of air move faster and move farther apart from each other. This causes the soap to puff up and expand.

The post The Amazing expanding bar of soap appeared first on Science Cafe.

• Apples (bigger is better)
• Knife (a butter knife will wok just fine)
• Potato peeler
• A few tablespoons of lemon juice
• 1/2 cup of salt
• 4 cups of water
• String

Start with a nice big apple that has the stem still attached. You will eventually hang the head to dry from the stem so keep it attached. If your apple is missing a stem you can thread a wire through the core and use a large button to support the bottom of the head. Remove the skin from the apple with the potato peeler or knife. You can leave a little at the top and bottom. A freshly peeled apple will begin to brown as the oxygen in the air begins to oxidize the surface of the fruit. We can slow this down by coating or dunking the fruit in a mixture of lemon juice and salt.

One of the hardest parts of carving a shrunken head to where to start? I’ll show you how I carve my heads, then you can use this as a starting point for your own creations. Step one is to create the ears. Turn your apple so you have plenty of working material on the sides. Start by marking off a big square on the side. Now remove the fruit around the outside of the square to reveal a sort of blocky looking ear.

Shape up the ear by cutting the corners back and boring an ear canal. Remember, we are going to shrink this head so carve the features BIG. Small details will be lost after shrinking so go for really BIG features. Once you have one ear completed, turn you head around and make another one on the other side. If you want the ear to really look good when dry, carve a little indent around the base where it attaches to the head. When dry the ear will have a bit more depth.

Now to start the face outline the forehead and nose with a few simple lines. Once you have this in place bring your knife in from the sides to create an eye socket. You may want to cut the lines around the nose a bit deeper than the forehead line. Be careful when making the eye sockets that you don’t pop off the nose! Use a pencil or chopstick to create a hole for the eye in the socket. Once the apple is dry you can push in a whole clove or pepper corn here for an eyeball.

Under the nose carve a little space to separate the nose from the lips. If you nose is really big, you might be able to drill in two nostril holes that will show up when dry. If you nose is small don’t bother. Often you won’t have enought material for a big set of lips since the bottom of the apple usually tapers down. If you have enough, make them big and make sure to make an upper and lower lip. Cut a deep slit between them so as they dry they will become separate lips. Another option for the mouth is to just make a deep cut and when things are all dried out you can add some dry rice for teeth!

Now you are ready for the salt water soaking. Ideally you want to soak your head for 24 hours in the salt water. This will help draw water out of the apple to help with shrinking. If you’re impatient, just give it a short soak and then hang it up to dry. Ideally you want a nice dry location for your head. I would avoid trying to dry the head in a moist bathroom! You can speed up the drying process a bit by placing the apple in the oven at a really low temp (~150 degrees) for an hour or two before setting aside to dry. After about 1-2 weeks your head should be ready. Be sure to check on your head periodically and if any mold is growing you can remove it with a cotton swab.

If you really want to dress up your head, you can add whole cloves for eyes, maybe rice for teeth, some yarn or fake hair on top might look nice. Add coloring to your head with charcoal or use food coloring as a paint. If you have an old Halloween wig around you can use some of that hair to make it look more spooky. It’s up to you! While I’ve never tried it, I’ve heard you can use a craft sealer, wood sealer or shellac to seal and preserve your head. Make a few heads and experiment to see what works for you.

That’s it! Use your imagination, have fun and let us know how it works for you!

The post How to make a shrunken head appeared first on Science Cafe.

What can I feed my crab?
Pretty much anything because they are omnivores and scavengers. Here is a small list of what they will eat.

• popcorn
• cheerios
• shrimp
• sardines
• turkey
• chicken
• salmon
• fish flakes
• spirulina
• oatmeal
• granola
• nuts (almonds, pecans, walnuts, pistachios, peanuts, cashews)
• peanut butter
• wood
• leaves
• scrambled eggs
• organic baby food
• freeze dried shrimp
• naturally dried red seaweed algae
• chickpeas (a.k.a. garbanzo beans)
• dulse (seaweed)
• alaria (seaweed)
• hamburger
• coconut
• strawberry
• banana
• dried brine shrimp

What CAN’T I feed my crab?

• Aloe vera (interferes with potassium absorption)
• Dill
• Garlic
• Geranium
• Ivy (of any kind)
• Onion
• Peppermint
• Pine, cedar wood or needles
• Rosemary
• Thyme
• Citrus (leaves and branches are to be avoided because they are part of the evergreen family. The fruit is fine.)

What type of shells do I give my crabs?
It is recommended that you offer you’re hermit crabs natural unpainted shells to choose from. The painted shells can chip and the paint is unhealthy for the hermit crabs.

Where can I buy shells?
You can buy your shells from a pet store or you can buy shells from a craft store. If you buy your shells in a craft store you should boil the shells before you put them in the tank for the crabs. The shells should boil rapidly in de-chlorinated water for 10 minutes to kill any bacteria that may be in the shells. Make sure the shells are completely cool before you put them in the tank.

How can I tell if my crab is getting ready to molt?
The pre-molt symptoms (PMS) are:

• Digging
• Consuming large amounts salt or fresh water
• Soaking in the salt or fresh water dish
• Cloudy eyes
• Ashy looking exoskeleton
• Lethargic (inactive)
• Spilling water to dampen the sand

How do I take care of a molting crab?
Normally when hermit crabs molt they will bury themselves deep within the sand. You should never dig up your crab. You should leave the crab under the sand until it is ready to come back to the surface after it has molted. On rare occasions a crab will attempt to molt on the surface of the sand. If this happens it is recommended that you isolate the crab from the other crabs in the tank. This is because other crabs may bother or even try to eat another crab that is molting. You can cut a 2-liter bottle in half and put it over the crab. Make sure that you include water and food for the isolated crab. You can also move the crab to a second tank until it has finished molting. The crab will shed its exoskeleton and then eat it. The old exoskeleton contains nutrients that helps the new exoskeleton to harden. The crab will then return to normal activities like climbing and walking around the tank.

How long does it take for my crab to molt?
The length of time depends on the size of your crab. Small crabs will take a couple of weeks while large crabs will take up to three months.

How much sand do I need for my crab?
The amount of sand depends on the size of your crab. The sand depth can range from 2 inches for small crabs (1/2 inch or less in length) to 10 inches for very large crabs (three inches in length).

What is that sound?
Hermit crabs actually make noises. They sound like a cross between a cricket chirping, a frog croaking, and a squeaky hinge on a door. It is unclear how the crab makes this noise, some think that there are two plates of exoskeleton inside the crab that rub together. Hermit crabs make this noise when they are agitated. So if you hear your hermit crab sing it isn’t happy!

The post FAQ about Hermit Crabs appeared first on Science Cafe.