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My best times tide pooling and snorkeling are when I go with a beginner who is excited about learning the names and behaviors of the fish we see.

Of course, this often puts me on the spot because invariably the novice asks a question that I should know but don't.

This happened recently during a trip to Hanauma Bay with my friend, Tim, who recently moved to Oahu.

Since it was early morning, and one of those calm days that makes you glad to be alive in Hawaii, we decided to first walk to the area of the bay called the Toilet Bowl. On the way, Tim stopped at nearly every tide pool to search for marine treasures.

He found a good one. "Susan, look," he called from a ledge near the ocean. "These fish are jumping from this pool right into the ocean!"

But I didn't see it. By the time I arrived, all the fish had bailed.

Then we began searching in earnest, tiptoeing up to pools to look for these acrobatic fish. And sure enough, several small, dark fish eventually leapt an amazing distance either to another pool or into the ocean.

They did it so fast, however, I didn't get a good look at them. And when I peered at the fish left in the pool, they hid under rocks.

I knew the question before it came: What are these fish and why are they jumping?

"They're blennies, I think. Or they could be gobies ... "

"And they're jumping because?"

"I don't know."

Fortunately, I have a good marine library at home where I could look it up. Now I'm pretty sure which fish were jumping and why: They were zebra blennies that jumped into the pools to graze on algae, usually abundant there.

When we startled the fish, they jumped back to safety on the ocean floor.

Blennies (paoo) are small fish ranging in size from just under 2 inches to about 7 inches long. Although over 300 blenny species exist worldwide, Hawaii hosts only 14.

On the reef, some blennies back into holes tail-first, then instantly duck inside the hole when threatened.

Because several blennies are experts at leaping from pool to pool or from ocean to pool and back again, they are sometimes called rockskippers.

Hawaii's three rockskipping blennies are the bullethead rockskipper, the zebra rockskipper (or zebra blenny) and Strasburg's blenny.

Colors vary among these three fish, even among individuals of the same species.

Some bear bars, stripes or spots; others are solid black, gray or tan.

The most distinguishing feature of all three, however, is the presence of filaments and/or tentacles over the eyes. These look like long eyelashes or the antennae of My Favorite Martian, giving the fish an endearing look.

Because the zebra rockskipper's tentacles are the most prominent, and Tim and I both noticed them, I think we saw zebra blennies that day.

My guess of gobies (oopu), however, was not far off. Although most gobies species live on sandy or silty ocean bottoms, some, such as the Cocos frill goby, are also common in Hawaii's tide pools.

To identify leaping tide pool fish, look for those cute eye tentacles and filaments. Gobies don't have them.

I look forward to my next snorkeling trip with Tim. I'm almost certain to learn something new.