Melissa George – NOAA Teacher at Sea Blog

August 1, 2013August 20, 2021

Melissa George: Catch Me if You Can, July 31, 2013

NOAA Teacher at Sea
Melissa George
Aboard NOAA Ship Oscar Dyson
July 22 – August 9, 2013

Mission: Pollock Survey
Geographical Area of Cruise: Gulf of Alaska
Date: July 31, 2013

Current Data From Today’s Cruise

Weather Data from the Bridge (12 noon Alaska Daylight Time)
Sky Condition: Cloudy
Temperature: 12.8 ° C
Wind Speed: 14 knots
Barometric Pressure: 1024.7 mb
Humidity: 89%

Clouds Seen from Bow of Oscar Dyson on July 31, 2013

Sun and Moon Data
Sunrise: 6:03 am
Sunset: 10:28 pm

Moonrise: 1:06 am
Moonset: 5:58 pm

Geographic Coordinates at 12 noon (Alaska Daylight Time)

Latitude: 59° 39.3′ N
Longitude: 157° 51.2′ W

The ship’s position now can be found by clicking: Oscar Dyson’s Geographical Position

Science and Technology Log

The main goal of Leg 3 of this mission is to survey the mid-water portion of the pollock population using acoustics and trawls. Pollock usually inhabit the middle of the water column down to the seafloor. This mid-water survey is typically carried out once every two years. Another NOAA Fisheries survey observes the pollock that live close to the seafloor using bottom trawls.

Trawling

The Oscar Dyson carries three different types of trawling nets for capturing fish as part of the mid-water survey: the Aleutian Wing Trawl (AWT), a mid-water trawl net called the Poly Nor’Eastern bottom trawl, a net with special rubber bumpers so it can bounce along the ocean floor; and the Methot, a small encased net that gathers very small ocean creatures such as krill. I will be discussing trawling with the AWT in this blog.

leg 3 — Leg 3 of the Mid-Water Survey Began East of Kodiak and Will End Near Yakutat

First, I will describe the AWT net, then I will explain how it works. The AWT net is HUGE: the mouth is about 25 m high and 35 m wide while the net itself is over 150 m long (this is not counting the trawling wires that it is attached to!). To give you an idea of how big this is, let’s think in school buses. If we estimate a school bus to be about 10 m long, then this net would be 15 school buses long, and its mouth would be 3 school buses wide and 2 school buses (end to end) tall. The picture below also gives perspective in dimensions (keep in mind that the Blue Whale is only used to give relative dimensions, they are never caught in NOAA’s nets!)

Relative Dimensions of AWT Net (courtesy of Kresimir Williams)

I am going to describe how the net goes into the water, step by step. Then you can watch a short sped-up video that my fellow Teacher at Sea mate, Julia Harvey, created. She works the night shift (4 pm to 4 am) on the same cruise that I am on.

So here it goes…

Step 1: The Codend

When the net is deployed from the ship, the first part of the net to hit the water is called the codend (see the far right of the diagram above). This is where most of the fish end up after the trawl. The mesh size of the net is smallest at the codend (about 1 cm) and gets larger as it approaches the doors (about 1 m).

Labeled Scale Model of the Aleutian Wing Trawl (AWT) Net (courtesy of NOAA Scientist Kresimir Williams)

Step 2: The Trawl Camera

A trawl camera is the next major part that hits the water. This is a pair of cameras that help scientists identify and measure the fish that are caught in the net. This technology can also be used to help scientists validate their biomass estimate from trawling sampling counts. This piece of equipment has to be clipped into the side of the net each time the crew is instructed to deploy the AWT.

Step 3: The Kite

The next piece of the net to hit the water is the kite which is secured to the head rope. Attached to the kite is a series of sensors that help the scientists gather data about the condition of the net including depth, size, and shape underwater. The major acoustic sensor, affectionately termed the turtle, can tell the scientists if the fish are actually going into the net.

Close-up view of the AWT scale model to highlight the kite and the turtle that ride at the top of the net. The third wire holds the electrical wires that send data from the turtle to the bridge.

Step 4: Deployment from A-Frame

Once the kite is deployed, a pair of tom weights (each weighing 250 lbs), are attached to the bridal cables to help separate the head rope from the foot rope and ensure the mouth of the net will open. Then, after a good length of cable is let out, the crew transfers the net from the net reel to the two tuna towers and attaches the doors. The doors act as hydrofoils and create drag to ensure the net mouth opens wide.

The scientists use acoustic data to determine at what depth they should fish, then the OOD (Officer on Deck) uses a scope table to determine how much cable to let out in order to reach our target depth. Adjustments to the depth of the head rope can be made by adjusting speed and/or adjusting the length of cable released.

The scientists use more acoustic data sent from the turtle to determine when enough fish are caught to have a scientifically viable sample size, then the entire net is hauled in. Once on board, the crew uses a crane to lift the codend over to the lift-table. The lift-table then dumps the catch into the fish lab where the fish get sorted on a conveyor belt. Click on Julia’s video below to see the entire process (sped up to retain the your interest!)

Personal Log:

Belongingness

Continuing with Maslow’s hierarchy of needs, I will discuss some of the ways that the need of belongingness is met on the Oscar Dyson. There are several different ways that comaraderie is fostered on the ship: teamwork, common areas, meal time, and celebrations.

A Version of Maslow's Hierarchy of Needs — A Version of Maslow’s Hierarchy of Needs

Teamwork

Remember the main goal of Leg 3 of this mission is to survey by acoustic-trawl the mid-water portion of the pollock population. To ensure that the goal of the mission is accomplished, several crews are necessary: engineering, officer, deck, and science crews. People assigned to a crew work together, and there is cross-talk between crews. For example, on the bridge where the officers work, there are two to four people navigating the ship and instructing the deck crew. The deck crew works together to put out and pull in the trawling nets, and the engineering crew works together to make sure the ship is operating properly. Similarly, the scientist crew members consult with each other while: reading the acoustics on the computer screens; deciding when, where, and how long to trawl; determining the best way to process the trawl; and reconciling the “catch” with the acoustical data. The collaboration within and between the four crews mimics a sports team that has offensive and defensive strings working together to maintain their positions to accomplish a common goal.

Common Areas

The ship is like a house with many rooms. Most of the staterooms (bedroom/bath) are shared. In terms of “living space” there is one dining area (called the galley), a conference room with books where people meet for drills or quiet work, a movie room, a laundry room, and an extra rest room. Because all these areas are shared, “ship etiquette” is followed, meaning that every individual keeps his or her space neat and also keeps the other common areas clean and organized. Sometimes, reminders are placed in areas where ship etiquette needs polishing.

Reminder of Ship Etiquette in Common Restroom

Meal Times
Meals on the Oscar Dyson are during one hour windows three times a day. Breakfast is served from 7 to 8 am, lunch 11am to noon, and dinner 5 to 6 pm. Unless people are sleeping or actively involved in trawling or processing, they eat at these times. Therefore, mealtime is a time to chat, joke, ask questions, and tell stories.

Galley Reminder


Celebrations
We have had three celebrations. Two of these were for birthdays celebrated on the ship. The stewards made a cake for dessert in one instance and hosted an ice cream social in the second. Another celebration was when we were in Prince William Sound to pick up net repair supplies. Because we were near land for the first time in many days and the sun was shining, many people came on deck at the same time to take pictures. Some spotted porpoises which added to the excitement. Fellow Teacher at Sea, Julia Harvey, captured a wonderful video of this event.

Did You Know?

The ship stewards are the people who plan and prepare the meals for those on board. Adam (below) is the second cook on the Oscar Dyson. He worked in various restaurants in Portland before coming to NOAA as a General Vessel Assistant (GVA) helping with the different crews on various ships as needed. When the spot as a steward opened on the Oscar Dyson, Adam got the job. He has taken various NOAA training courses for stewardship and is on the ship nine months out of the year as it surveys both in the Bering Sea and the Gulf of Alaska.

Something to Think About:

Today’s episode of Trawling Zoology features the animal family, Cnidaria. Cnidaria is a word that originates from the Greek word cnidos which means “stinging nettle.” Although the cnidarians are a very diverse family, all the members contain nematocysts (combination of Greek words nema meaning “thread” and kystis meaning “bladder”), basically barbed threads tipped with poison. If you have ever been stung by a jellyfish, you have felt this stinging sensation.

There are four very diverse groups of cnidarians: Anthozoa which includes true corals, anemones, and sea pens; Cubozoa, the amazing box jellies with complex eyes and potent toxins; Hydrozoa, the most diverse group with siphonophores, hydroids, fire corals, and many medusae; and Scyphozoa, the true jellyfish. We have brought up several members of these groups in our trawling.

Anthozoa: We have brought on deck both sea pens and sea anenomes. In both groups there was only one species represented.

Sea Anenomes (hermit crabs in front are not anthozoans)

Schyphozoa: We brought up a couple of different species of jellyfish; we used a classification field guide to help us identify them.

Jellyfish from the Invertebrate Field Guide for Alaskan Waters

Many Jellies (members of the Aequorea genus) Found in the Methot Trawl

To learn more about the Cnidaria Family, click the Cnidaria on the picture below, and stay tuned for further exploration of this animal Tree of Life.

Can you spot the Cnidarian on the Tree of Life? Click on it to learn more.

July 28, 2013August 20, 2021

Melissa George: Do You Hear What I Hear? July 28, 2013

NOAA Teacher at Sea
Melissa George
Aboard NOAA Ship Oscar Dyson
July 22 – August 9, 2013

Mission: Pollock Survey
Geographical Area of Cruise: Gulf of Alaska
Date: Sunday, July 28, 2013

Current Data From Today’s Cruise

Weather Data from the Bridge
Sky Condition: Cloudy
Temperature: 14° C
Wind Speed: 4 knots
Barometric Pressure: 1025.1 mb
Humidity: 90%

Sun and Moon Data
Sunrise: 5:57 am
Sunset: 10:34 pm

Moonrise: 11:52 pm (July 27, 2013)
Moonset: 2:35 pm

Geographic Coordinates at

Latitude: 59° 53.3′ N
Longitude: 149° 00.0′ W

The ship’s position now can be found by clicking: Oscar Dyson’s Geographical Position

False Point on Kenai Peninsula (viewed this morning through the fog)

Science and Technology Log

How do scientists use acoustics to locate Pollock (and serendipitously other ocean creatures)?

Scientists aboard the NOAA Research Vessel Oscar Dyson use acoustic, specifically hydroacoustic data, to locate schools of fish before trawling. The trawl data provide a sample from each school and allow the NOAA scientists to take a closer look by age, gender and species distribution. Basically, the trawl data verify and validate the acoustics data. The acoustics data, collected in the Gulf of Alaska in systematic paths called transects, combined with the validating biological data from the numerous individual trawls, give scientists a very good estimate for the entire Walleye pollock population in this location.

This screen is showing the echogram from the EK 60 echosounder during a trawl at 83.13 meters. The red line in the middle of the screen is the ocean floor. The colorful spikes above the red line indicate “backscatter” that is characteristic of capelin, a small fish that pollock feed on.

Hydroacoustics (from Greek words: hydro meaning “water” and acoustics meaning “sound”) is the study of sound in water. Sound is a form of energy that travels in pressure waves. In water, sound can travel great distances without losing strength and can travel fast, roughly 4.3 times faster in water than in air (depending on temperature and salinity of the water).

Click on this picture to see how sound travels from various ocean creatures through water. (Photo from sciencelearn.org)

The Oscar Dyson has powerful, extremely sensitive, carefully calibrated, scientific acoustic instruments or “fish finders” including the five SIMRAD EK60 transducers located on the bottom of the centerboard, the SIMRAD ME70 multibeam transducer located on the hull, and a pair of SIMRAD ITI transducers on the trailing edge of the centerboard.

Image of acoustic instruments on the Oscar Dyson. (Photo courtesy of NOAA Teacher at Sea Program)

This “fish-finder” technology works when transducers emit a sound wave at a particular frequency and detect the sound wave bouncing back (the echo) at the same frequency. When the sound waves return from a school of fish, the strength of the returning echo helps determine how many fish are at that particular site.

The green ship’s transducer is sending out sound waves towards the fish. The waves bounce back echoes towards the ship that are received by the transducer. (Photo courtesy of Oracle Thinkquest)

Sound waves bounce or reflect off of fish and other creatures in the sea differently. Most fish reflect sound energy sent from the transducers because of their swim bladders, organs that fish use to stay buoyant in the water column. Since a swim bladder is filled with air, it reflects sound very well. When the sound energy goes from one medium to another, there is a stronger reflection of that sound energy. In most cases, the bigger the fish, the bigger the swim bladder; the bigger the swim bladder, the more sound is reflected and received by the transducer. The characteristic reflection of sound is called target strength and can be used to detect the size of the fish. This is why fish that have air-filled swim bladders show up nicely on hydroacoustic data, while fish that lack swim bladders (like sharks) or that have oil or wax filled swim bladders (like Orange Roughy), have weak signals.

The above picture shows the location of the swim bladder. (Photo courtesy of greatneck.k12.ny.us)

These reflections of sound (echoes) are sent to computers which display the information in echograms. The reflections showing up on the computer screen are called backscatter. The backscatter is how we determine how dense the fish are in a particular school. Scientists take the backscatter that we measure from the transducers and divide that by the target strength for an individual and that gives the number of individuals that must be there to produce that amount of backscatter. For example, a hundred fish produce 100x more echoes than a single fish. This information can be used to estimate the pollock population in the Gulf of Alaska.

The above picture shows a computer screen with dense red “backscatter” characteristic of large amount of fish. The yellow lines above and below the backscatter show the location of the trawl lines. — The above picture shows a computer screen with dense red “backscatter” characteristic of large amount of fish, most likely pollock. The yellow lines above and below the backscatter show the location of the trawl lines.

Personal Log:

Safety

Continuing with Maslow’s hierarchy of needs, I will continue up the pyramid (see below) and discuss some ways that the basic need of safety is met on the ship. The safety and security of all staff (as well as sea animals we encounter) are top priority on the Oscar Dyson. There are constant reminders of this priority during ship life.

: A Version of Maslow’s Hierarchy of Needs

Safety Drills

On the first day of our travel, before the Oscar Dyson was far from port at Kodiak, we had three drills. The fire drill and man overboard drill required me to report to the conference room and meet up with the rest of the science team. Patrick, the lead scientist, then reported that we (the scientist team) were all accounted for. The crew had more complex tasks of deploying a small boat and retrieving “the man overboard”.

The other drill was the abandon ship drill. On the ship, every person is assigned to a life boat (mine is Lifeboat 1). When the drill commenced, I reported to my muster, the portside of the trawl deck, with survival gear: jacket, hat, survival suit and life preserver. We will have drills weekly at anytime.

Safety Gear

When working in the lab, the scientists wear orange slickers, boots, and gloves, not only to keep clean, but to protect us from anything that might be dangerous (fish spines, jellyfish tentacles, and so on). When on deck, we must wear hardhats (to protect from falling objects from the crane or trawl) and life preservers like the rest of the crew.

Water Tight Doors

Watertight doors are special types of doors found on the ship which prevent the flow of water from one compartment to other during flooding or accidents. These doors are used onboard in areas, such as the engine room compartment, science and acoustics labs, and control bridge, where chances of flooding are high.

These are just a few examples of how safety is emphasized on the ship. There are reminders in one’s line of vision constantly.

Safety, Everyone's Responsibility — Safety, Everyone’s Responsibility

Did You Know?

There are various seafarer or crew positions on the Oscar Dyson. A ship’s crew can generally be divided into three main categories: the deck department, the engineering department, and the steward department. Rob and Greg are members of the deck department; both men hold Merchant Mariner Credentials as “Able Bodied Seamen” or ABS. Rob is from Boston, Massachusetts and went to school for seamanship in Fairhaven, MA. He considers his NOAA position as a good job with a good income, but his main profession is lobstering which he does on the open sea when he is not working for NOAA. Rob says, “The ocean is in my blood” and always wanted to work on it. Greg, on the other hand, chose to be a Merchant Mariner after a voyage at sea. He moved to Texas from Louisiana in his 20’s, went fishing for the first time, and got seasick. He considered battling seasickness a challenge, and thus pursing seamanship as a career. In his free time he is a free-lance photographer and journalist. Below are some pictures of Greg and Rob on the job. Notice they are always wearing their safety gear.

Greg and Rob Bringing in the Trawling Net

Greg and Rob, Preparing for a Camera Drop

Something to Think About:

Since I will begin teaching Zoology later in August, I have decided to highlight some of the animals that the scientist team has found in our trawls. Today’s feature will be one of the simplest multicellular animal families, the Porifera. Porifera is a word formed from combining the Latin words porus which means “passage-way” and fera meaning “bearing.” Porifera, commonly referred to as sponges, have tiny pores in their outer walls that filter water to get nutrients.

Various Porifera (Sponges) from a Bottom Trawl

Teacher (me) Demonstrating How Water Flows out the Osculum (opening) of a Poriferan

To learn more about the Porifera Family, click the Porifera on the picture below, and stay tuned for further exploration of this animal Tree of Life.

Tree of Life: Can you spot the Poriferan?

July 26, 2013August 20, 2021

Melissa George: Crossing the Line, July 25, 2013

NOAA Teacher at Sea
Melissa George
Aboard NOAA Ship Oscar Dyson
July 22 – August 9, 2013

Mission: Pollock Survey
Geographical Area of Cruise: Gulf of Alaska
Date: Thursday, July 25, 2013

Current Data From Today’s Cruise

Weather Data from the Bridge (at 6:00 am Alaska Daylight Time)
Sky Condition: Fog
Temperature: 12° C
Wind Speed: 11 knots
Barometric Pressure: 1017.5 mb
Humidity: 87%

Sun and Moon Data
Sunrise: 5:51 am
Sunset: 10:40 pm

Moonrise: 10:57 pm (July 24, 2013)
Moonset: 10:37 am

Geographic Coordinates (at 6:00 am Alaska Daylight Time)

Latitude: 58° 30.5′ N
Longitude: 148° 47.7′ W

The ship’s position now can be found by clicking:

Oscar Dyson’s Geographical Position

Science and Technology Log

How can you determine the population size of species? You could count every member of the population. This would be the most accurate method, but what if the individuals in the population move around a lot? What if the population is enormous and requires too much time to count each individual? For example, krill is a small crustacean (usually between 1 and 6 cm long) that accounts for 400-500 million metric tons of biomass in the world’s oceans. Would you want to count all of the krill in the Gulf of Alaska?

Often, ocean populations of animals are just too large to count. Sampling, or collecting a manageable subset of the population and using the information gathered from it to make inferences about the entire population, is a technique that ocean scientists use. There are a variety of ways to sample.

One method is called mark and recapture. In this method, one catches individuals from the population, tags them, and releases them in a certain area. After a set amount of time, an attempt is made to recapture individuals. Data are compiled from the recaptures and the population is mathematically calculated. Tuna populations in some areas are monitored this way; fishermen are required to report any fish that are recaptured. (Photo courtesy of Western Fishboat Owners’ Association)

Another method is quadrat sampling. The organisms in a subset area (quadrat) are counted and then the overall population in the entire area is calculated. For example, in the picture below, one quadrat would be randomly selected and the organisms counted. From this count the overall population would be extrapolated. (Photo courtesy of BBC Bitesize Biology)

The sampling method used on the Oscar Dyson employs the use of a transect line. The picture below illustrates the use of a transect line. On various increments along the transect line, samples of populations are taken. Imagine the Oscar Dyson’s path on the sea as the measuring tape and the trawl net is the sampling square. (Photo courtesy of Census of Marine Life Organization)

The overall survey area of the pollock study this summer is the northern Gulf of Alaska between the shore and the continental break. Within this area transect lines were established. These are pathways that the Oscar Dyson will travel along and periodically take samples of the fish.

The current set of transects are 25 nautical miles apart and are parallel, but transects in other areas may be 2 or 5 nautical miles apart. One nautical mile is equal to 1/60 of a degree (or 1 minute ) of latitude. Transects that we are following now are located on the shelf and are perpendicular to the coastline. Transects in inlets and bays may run differently, perhaps even zigzag.

Screen Shot of Oscar Dyson Transect Line Travel

If fish are located through acoustics monitoring off the transect line, the ship might break transect (a mark is made on the map), circle around to the desirable position, and collect a sample by trawling. The population of pollock can then be mathematically calculated from counting the sample. After trawling, the ship will return to the break and continue along the transect line.

Most days, scientists hope that the Oscar Dyson will finish a transect line by nightfall and then the ship can be at the next transect by sunrise. This maximizes the time for detecting fish acoustically and trawling to collect samples.

Personal Log:

In his 1943 paper “A Theory of Human Motivation,” Abraham Maslow, a developmental psychologist, proposed a hierarchy of needs which focus on describing the stages of growth in humans. The largest, most fundamental needs are at the bottom, and as those are satisfied, individuals are able to progress up the pyramid. So, I am going to use this diagram (somewhat tongue-in-cheek) to discuss how basic needs are met on the ship. In today’s blog, I will begin the discussion at the bottom level (where else?).

The bottom layer includes the most basic physiological needs one requires for survival: food, water, warmth, and rest. (We might also include exercise in this level). So, let us begin at the beginning.

Food

Food is available in the galley. It is planned for and shopped for before the mission. Chief Steward, Ava, and Second Cook, Adam, do an excellent job preparing and executing delicious, healthy meals at set times during the day (Breakfast: 7 to 8 am, Lunch 11 am to noon, Dinner 5 to 6 pm). Since the staff on the ship are working around the clock, there is always food available (salad bar, cereal, yogurt, peanut butter and jelly sandwiches) if meal time is missed for sleeping. Below is a photo of the galley. (What are those neon yellow things on the bottom of the chair legs for, do you think?)

Water

Water is needed for in several capacities on the ship. The staff on the ship needs potable water to drink and to cook with. Additionally, water is needed for washing dishes, bathing, flushing toilets and doing laundry.

To get clean drinking water, we pump the salt water from the ocean into a desalination unit (a distiller). The distilled water is then sent to a 10,000 gallon holding tank. When water is needed, it is pressurized so that it will move to the faucets, drinking fountains, showers, and so on.

Water is also needed on the ship in the lab and on the deck to clean up after the catch is hauled in and processed. The water used here is salt water and is pumped onto the boat directly from the ocean.

Rest

Half of the staff on the ship is working around the clock; the other half is resting. For the science staff, there are two shifts, a morning shift (4 am to 4 pm) and an evening shift (4 pm to 4 am). The shifts are staggered at these hours so that the evening shift will be able to share two meals with the rest of the staff (usually lunch and dinner). In most cases, two people share a stateroom: one works days and the other works nights. Because the quarters are close on a ship, this gives each person some time alone in the room to sleep, bathe, and take care of other personal needs. A stateroom consists of a bunk bed, a desk, two lockers, and a bathroom/shower. Below are some photos of the stateroom that I share with my roommate, Abby. (Note: Because rooms are small and space is shared, it is not advisable to bring a large purple suitcase that won’t fit inside one’s locker.)

Exercise

There are two workout areas on the ship. One workout area has a treadmill, an elliptical machine, a bike, and a yoga mat; the other has a treadmill, a rowing machine, and some free weights. There are limited walking spaces on the ship, so these machines provide a way to stretch one’s legs, so to speak.

Did you Know?

With a bachelor’s degree in science, math, or engineering and a 6 month training program at the US Coast Guard Academy in New London, CT, one can serve the United States as a member of the National Oceanic and Atmospheric Administration’s Commissioned Officer Corps (NOAA Corps). Members of the NOAA Corps serve as operational experts, taking researchers to sea and helping to generate environmental intelligence. My roommate, Abby, serves as a member of the NOAA Corps.

This is Abby’s second cruise with the NOAA Corps. She has a bachelor’s degree in chemistry and just completed her NOAA officer basic training. One of her tasks is to be ready to deploy specific measures in case of a fire on board. Below, she is reviewing all of the locations on the Oscar Dyson with fire response equipment. For more information on NOAA Corps, click on the link.

Something to Think About

Knowing geography is essential to various positions on the ships such as scientific exploration and navigation. Many types of maps are seen on board, for example, computer generated bathymetric maps show the contour and depth of the ocean. Equally valuable are the “old school” tools (paper maps, compasses, straight edges, and pencils) used to plot the ship’s course.

Fun Fact

Etymology is the study of the origin of words. Many of the words in science originate from ancient languages such as Greek or Latin. For example, the word etymology comes to us from two Greek words: etymon meaning “the true sense of a word“ combined with logia meaning “doctrine, study.” Combining these two roots gives us “the study of the true sense of words,” which can be said to be the meaning of the word etymology.

Here are some root words I came across today all originating from Greek words:

zoo-from zoion meaning “animal”

phyto-from phyto meaning “plant”

plankton-from planktos meaning “drifting” or “wandering”

vorous-from vorous meaning “eating”

In the blogs thus far, I have discussed two species: walleye pollock and one of their prey, krill. Krill are classified as zooplankton, literally “animals that drift. ” Krill eat phytoplankton, or “animals that drift.” Pollock are considered to be zooplanktivorous, or “drifting animal eaters.” An award winning short video explaining The Secret Life of Plankton can be viewed by clicking on the link.