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Ask Dr. Universe Natural Resources

What is octopus ink? – Henry, 6, Maryland

Dear Henry,

An octopus has three hearts and long arms with suction cups. It probably seems very different from you. But you have the main ingredients of octopus ink in your body, too!

I talked about octopus ink with my friend Gretchen Rollwagen-Bollens, associate professor in WSU’s School of the Environment. She told me that ink isn’t just an octopus thing. Most animals called cephalopods (sef-uh-luh-pods) make it. These include octopus, squid and cuttlefish.

Cephalopods including octopuses use color a lot. They have sacs of colored pigments all over their bodies. They use those sacs to change their body color. That helps them blend into their environment.

They also make and store a dark pigment in special ink sacs.

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Dr. Universe: When would a clam open its shell? Why do the shells open? As far as I know, it opens when boiled for food. - Teng, 5, China

Dear Teng, There are a lot of different reasons why a clam might open its shell. My friend Jonathan Robinson, a marine ecologist at Washington State University, told me all about it. If we spent some time where the ocean meets the shore, or the intertidal zone, we might observe how clams open their shells when they need to eat, breathe or move around. Read More ...

Dear Dr. Universe: How many different types of plankton are there? Are there freshwater plankton? – Arielle, 11

We can find millions and millions of plankton in bodies of water all over the world—from oceans, rivers, and lakes to ponds and mud puddles. That’s what I found out from my friend Julie Zimmerman, a scientist with the Aquatic Ecology Lab at Washington State University. In the lab, researchers can use powerful microscopes to get an up-close look at these tiny creatures. Read More ...