5 June, 2000

The MocNess Monsters

June 5, Monday

Bulging black eyes stared me down. The transparent, jelly-like creature writhed menacingly back and forth. Suddenly it lunged towards me, its sharp fangs snapping ferociously.

I stepped away from the microscope and blinked my eyes a few times. The arrow worm didn't look quite as threatening from this angle. Only 4 centimeters long, it looked like an earthworm made of glass.

Viewed under the microscope, though, it looked an awful lot like those mythical sea monsters from sailors' tales of the deep. Inside the arrow worm's transparent body, I could make out the remains of its last meal. The reddish outlines of tiny shrimp-like creatures called copepods were easy to see.

Arrow worms and copepods are two kinds of zooplankton found in the ocean. Have you ever heard of krill? That's another kind of zooplankton. Zooplankton are small animals that range in size from microscopic to several centimeters long. These critters are extremely important because they are eaten by fish, shrimp, and large marine animals like whales. It takes a lot of tiny zooplankton to satisfy a hungry whale!

Earlier in the evening, Susan and I had helped Peter Lane, a marine biologist from the University of Miami, capture these critters in the MOCNESS. MOCNESS is an acronym that stands for "Multiple Opening and Closing Nets and Environmental Sampling System". It consists of a frame with a series of several long nets that are towed behind the ship. Each net captures zooplankton at different depths. The critters are then brought into the laboratory where Peter examines them.

First Peter counts the copepods. Copepods look like miniature versions of their cousins, the shrimp. They can grow up to 8 millimeters in length, but most are smaller than that. Because they are so tiny, it takes a long time to count them. So Peter divides the copepods into 10 equal groups, or samples. He counts all of the copepods in one sample, and then multiplies by 10. If he finds 500 copepods in one sample, then Peter calculates that there were 5,000 copepods caught in that net. It usually takes a whole day just to count one or two samples!

Then, depending on the type of experiment he is doing, Peter will look at different things. He might note the age of the copepods, their size, or whether they are male or female.

All of this information is recorded in a journal. The zooplankton are then poured into carefully labeled jars where they are preserved for further studies.

It takes a lot of patience to be a scientist, but the result is worth it! Peter's work with copepods and other zooplankton help scientists understand more about life in the ocean. The more knowledge we have, the better we can protect our oceans.

To find out how the MOCNESS works, click on Susan's page:

Susan’s Entry Today.

DAILY DATA LOG (6/05/00)

Air Temperature: 36 degrees F

Clear skies, sunny

Latitude 57N

Longitude 55W

Sunrise 5:04

Sunset 10:33

Actually, it never got DARK last night. For an hour or two in the middle of the night, it was more like dusk than night. But even at midnight you could see light on the horizon.

These samples are lined up in order of the depth they were collected. Can you see which one has the most zooplankton?

Each sample is clearly marked so that the scientists will know where and when it was collected.

Sunrise 5:04 and Sunset 10:33 Actually, it never got DARK last night. For an hour or two in the middle of the night, it was more like dusk than night. But even at midnight you could see light on the horizon. This picture was taken after midnight!