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Monterey Bay National Marine Sanctuary Teachers' Curriculum
"The Land-Sea Connection"

Cover | Table of Contents | Introduction | Background | Investigation 1 | Investigation 2
Glossary | Teacher Resources | Curriculum Evaluation | Credits

Investigation 2
A Close Look at Monterey Bay National Marine Sanctuary

Purple sea urchin (Laura Francis)
Purple sea urchin (Laura Francis)

In this investigation, students take a close look at Monterey Bay National Marine Sanctuary. After becoming familiar with a bathymetric/topographic map of the area, students select a transect along the seafloor to study some of the geological, biological, and physical features that are present.


Conducting a Transect Along the Seafloor: Monterey Bay National Marine Sanctuary

Learning Objectives

Students will:

  • Use a bathymetric/topographic map as a tool for recognizing geobiological features of the Sanctuary;

  • Create a depth profile from a topographic map;

  • Use a transect as a tool for quantifying geological, physical, and biological features along the seafloor;

  • Correlate species with habitat type in Monterey Bay National Marine Sanctuary.


Geography Standard 1
How to use maps and other geographic representations, tools, and technologies to acquire, process, and report information from a spatial perspective

Science Standard
Develop abilities necessary to do scientific inquiry

Develop understanding of populations and ecosystems

Activity: Conducting A Transect Along the Seafloor:
NOAA's Monterey Bay National Marine Sanctuary

Guiding Question

What if you were to conduct a horizontal transect in Monterey Bay National Marine Sanctuary, based upon the habitat types along your transect, what species would you expect to find? (See Background.)


Monterey Bay Sanctuary Bathymetric Chart, one for each group

Benthic Habitat Types in the MBNMS Area, one for each group

Animal Species in the MBNMS Area, one for each group

Metric ruler

Graph paper with x- and y-axis

Access to the Internet (optional)


The information for this activity may be substituted with that from another sanctuary. For example, the Florida Keys National Marine Sanctuary website has information about the coral reef habitat. Check out

As a result of extensive studies of the seafloor in Monterey Bay National Marine Sanctuary, much is known about its topography and sediment types. Sediment type is one of many factors that define the kinds of algae and animals living in a particular area. By knowing these sediment types, and the habitats preferred by different species, scientists can predict what organisms they might find in an area. Using underwater submersibles and other scientific equipment, scientists can compare their predictions with actual findings.

MBNMS contains one of the world's most geologically diverse and complex seafloors and continental margins. The MBNMS is located on a plate boundary which separates the North American Plate from the Pacific Plate, and is marked by the San Andreas fault system. This is an active tectonic region with common occurrences of earthquakes, submarine landslides, flood discharges and coastal erosion. It is also a region of extensive natural and economic resources. Coastal topography varies greatly, encompassing steep bluffs with flat-topped terraces and pocket beaches to the north; large sandy beaches bordered by cliff and large dune fields mid-sanctuary; and predominately steep, rocky cliffs to the south. Low-to high-relief mountain ranges and broad, flat-floored valleys are prevalent farther inland. (From Geology section of MBNMS Site Characterization at website:



Give each student a copy of the MBNMS Chart. Discuss with your students the different features on the map (contour lines reveal different seafloor features such as the continental shelf, canyons, seamounts, and banks). Discuss how geologists create these maps. (See below.) What are some ways scientists might use these maps? (Map data allows us to get a picture of the seafloor & its habitats. This tells us a lot about what plants and animals live there).


Explain to students that scientists conduct transect studies as one way to characterize the geological, physical, and biological characteristics of an ecosystem. Tell students that they are going to plan a research cruise in the Monterey Bay Sanctuary using an underwater submersible.

Please see "Meet DeepWorker" background information. Have students select a horizontal transect on their maps that they would be interested in studying. How do you determine the length and depth of a transect? The transect should be a straight line from one point on the map to another. Using a ruler, have each student draw a straight line on their map to indicate the location of the transect.


To help illustrate the underwater topography along a transect, have students make profile charts. On a separate piece of paper, have them create a "T" table: one column for distance from the starting point of their transect (Point A) and one for depth of the seafloor. Then have them collect data at every centimeter along their transect using the scale 1cm = 1 km. For example, measuring one centimeter on the ruler from Point A (which is equal to one kilometer from the starting point of their transect), the contour line indicates depth is 25 meters. At two centimeters (or two kilometers from Point A), the depth is 30 meters. (See following example).

Mapping the Seafloor Data
Transect in Monterey Bay National
Marine Sanctuary
Distance from start
Depth of Seafloor
0 km
0 m
1 km
25 m
2 km
30 m
3 km
30 m
4 km
35 m

Once students have collected data along their transects and created data tables, have them create profile charts to show the underwater topography. If computer graphing capabilities are not available, hand out graph paper and have students title and label their graphs: distance (km) along the bottom or X axis, and depth increments (m) along the side or Y axis. Students can refer to their data tables for ranges of values.


Have students use their data tables to plot the points on their profile charts, then draw a profile by connecting the points on the chart.

sample chart

Give each student a copy of the Benthic Habitat Types handout. Have them determine what kinds of sediments they would find along their transects and indicate these on their maps. Encourage students to ask questions about their findings; for instance, "Where did these sediments come from?," "How did they get here?," "Why are they distributed as they are in different zones?" Students may not have answers to these questions, but asking them is an essential part of doing science and is the first step in scientific inquiry. For more information, refer to the book "Natural History of Monterey Bay National Marine Sanctuary."


Give each student a copy of the Animal Species handout. Based on the sediments found along their transects, what species would they expect to find? What is their reasoning to support these expectations?



One of the fishes inhabiting NOAA's Monterey Bay National Marine Sanctuary is the center of study for an Expeditions investigation. Rockfish (Sebastes spp.) congregate in particular habitats in MBNMS. A related species, the Redfish (Sebastes fasciatus) inhabit similar areas in NOAA's Stellwagen Banks National Marine Sanctuary. By comparing the day and night habits of these two fish, scientists hope to find relationships between them which might prove useful when making decisions to best protect their populations.

Discuss with students the relationships among the organisms, their physical surroundings, and their geographical location. What physical conditions does each organism favor? Does the organism's predators and prey favor the same conditions? What kinds of patterns can be seen among organisms, physical conditions, and their geographical location?


If you have access to the Internet, have students refer to the Sustainable Seas Expeditions website ( and to follow the research being conducted in Monterey Bay National Marine Sanctuary. What species are the Sustainable Seas Expeditions researchers finding? How do these findings compare with the predictions made by students?


Have students write a detailed description of their findings. If they were able to follow the Sustainable Seas Expeditions research project on the web, have them draw conclusions about their predictions and the actual findings.

How are seafloor maps created?

In Most of our knowledge about seafloor topography comes from soundings: sending sound waves into the water and measuring the time it takes for them to bounce off the ocean floor and return. From these soundings, scientists can create a map of the seafloor.

The device used to send sound waves is called an echo sounder, or sonar. Towed behind a ship, it bounces about 120 narrow beams of sound, also called "pings," off the seafloor several times per second. Another instrument collects the sound that echoes back. The ship passes back and forth over a given area, much the way you mow a lawn, sending these many beams of sound as it goes. A computer on board the boat calculates the depth based on the time it takes for the echo of the beam to return to the surface. Sound travels through the ocean at an average speed of 1,460 meters (4,800 feet) per second. (Sound travels about five times faster through water than it does through air.) To calculate the depth, divide the total amount of time it takes for a ping to hit the bottom and bounce back by two. (You divide by two because the total includes the trip down and back.) Then multiply that figure by 1,460. For instance, if it takes two seconds for sound to return to the ship, the water must be 1,460 meters deep.

At the same time, the sonar gathers information about the composition of the ocean floor by measuring the strength of the returning signal.

For example, mud absorbs sound, therefore a muted echo indicates a muddy bottom. A strong echo indicates a rocky bottom. Scientists supplement these sonar images with videos, still photographs, and samples.

For more information on seafloor mapping, see:

Monterey Bay Sanctuary Bathymetric Chart
Monterey Bay Sanctuary Bathymetric Chart

Monterey Bay Sanctuary sediment Chart

Monterey Bay Sanctuary Sediment Chart

JPEG version

JPEG version

a PDF version of these images can be found in the fullcurr.pdf document (2.7mb)


Common Name: Olive snail
Scientific NameOlivella biplicata
Habitat Preference: fine sand
Prey: algae & dead animals
Predators: sea stars

Common Name: Red octopus
Scientific Name: Octopus
Habitat Preference: rocky outcrops
Prey: small crustaceans, mollusks and fishes
Predators: demersal fish, herring, striped bass, sea turtles, humans

Common Name: Pismo clam
Scientific Name: Tivela stultorum
Habitat Preference: coarse and medium sand
Prey: phytoplankton, small detritus
Predators: sea otters, crabs, moon snails, sharks, rays, shorebirds, & humans

cold seep clamsCommon Name: Cold seep clams
Scientific Name: Calyptogena spp.
Habitat Preference: Cold seep areas in the deep canyon floor.
Coarse sediment with silt and clay
Prey: chemosynthetic bacteria live in the clams gill tissues and provide their sole source of nutrition
Predators: unknown

Common Name: Sea stars
Scientific Name: Patira miniata (bat star), Pisaster giganteus(Giant seastar), Astropecten armatus (sand star),
Habitat Preference: coarse and medium sand, rocks
Prey: bivalves, small crustaceans, worms, other echinoderms, detritus, carcasses, tunicates, hydroids, sea anemones, sponges
Predators: larger sea stars, gulls & humans

Common Name: Hydroid
Scientific Name: Aglaophenia spp. (ostrich-plumed)
Habitat Preference: gravel, sand
Prey: zooplankton, phytoplankton, small detritus
Predators: nudibranchs, echinoderms, benthic fish (flounders, sculpins)

Common Name: Nudibranchs & Opistobranchs
Scientific Name: Anisodoris noblis (Sea lemon), Pleurobrachia california (Deep sea hare)
Habitat Preference: rocky outcrops
Prey: (selective by species) hydroids, sea anemones, cerianthids, corals, bryozoans, sponges
Predators: sea stars, crabs, lobster, some benthic fish

Common Name: Tube-dwelling anemone
Scientific Name: Pachycerianthus fimbriatus
Habitat Preference: fine sand or mud
Prey: small zooplankton, detritus, small animals that get caught on tentacles
Predators: nudibranchs, sea stars, some bottom-feeding fish (cod, flounder, haddock)

Common Name: Sea anemones
Scientific Name: Corynactis californica (strawberry anemone), Metridium senile (plume anemone)
Habitat Preference: rocks
Prey: zooplankton, detritus, small animals that get caught on tentacles
Predators: nudibranchs, sea stars, bottom-feeding fish

Common Name: Crabs
Scientific Name: Cancer magister (dungeness crab), Pagurus samuelis. (hermit crab)
Habitat Preference: boulders, gravel
Prey: phytoplankton, protozoa, small detritus
Predators: nudibranchs, sea turtles, sea urchins, sea stars

Common Name: Bryozoans
Scientific Name: Filicrisia franciscana
Habitat Preference: rocks & shale
Prey: phytoplankton, protozoa, small zooplankton, small detritus
Predators: nudibranchs, crabs

Common Name: Tunicate (carnivorous)
Scientific Name: Megalodicopia hians
Habitat Preference: deep area of canyon walls
Prey: copepods, krill, & other zooplankton
Predators: unknown

Common Name: Giant tube worms (grow up to 1 meter long)
Scientific Name: Riftia spp.
Habitat Preference: hot hydrothermal vents found on the deep seafloor of the canyon; shale and mud
Prey: chemosynthetic bacteria live in the worms tissues and provide nutrition
Predators: unknown

Common Name: Sand dollar
Scientific Name: Dendraster excentricus
Habitat Preference: fine sand & muddy bottoms
Prey: benthic algae, bryozoans, encrusting sponges, small detritus, small copepods
Predators: sheephead, starry flounder, pink sea star, gulls

Common Name: Purple sea urchin
Scientific Name: Strongylocentrotus purpuratus
Habitat Preference: rocky outcrops
Prey: benthic algae, small detritus, plankton
Predators: sea stars, some fishes (California sheephead), sea otters, & humans

Common Name: Common squid
Scientific Name: Loligo opalescens
Habitat Preference: open water, muddy sand (for spawning)
Prey: shrimplike crustaceans, small fishes, benthic worms, & their own young
Predators: Many fishes, birds, marine mammals & humans

Common Name: Blue rockfish
Scientific Name: Sebastes mystinus
Habitat Preference: kelp plants & rocky areas
Prey: mollusks, squid, crustaceans, worms,
Predators: bigger fishes, young preyed upon by many pelagic species, humans

Common Name: Cabezon
Scientific Name: Scorpaenichthys marmoratus
Habitat Preference: rock & gravel
Prey: demersal fish, abalone, crustaceans, mollusks, echinoderms, worms, also scavenges on carcasses
Predators: humans

Common Name: Tidepool sculpin
Scientific Name: Oligocottus maculosus
Habitat Preference: shallow rocky areas
fish graphicPrey: demersal fish, crustaceans, mollusks, echinoderms, worms, also scavenges on carcasses
Predators: young eaten by many bottom fish

Common Name: California halibut
Scientific Name: Paralichthys californicus
Habitat Preference: fine or coarse sand
Prey: small fishes, crustaceans
Predators: pelagic and benthicl fish, squid, marine mammals, sea birds

Common Name: Pacific herring
Scientific Name: Clupea harengus
Habitat Preference: open water, gravel for egg laying
fish graphicPrey: small fish, zooplankton (especially copepods), amphipods, mysids, shrimps, worms
Predators: many pelagic and benthic fish, squid, marine mammals, sea birds, humans

Common Name: Lanternfish
Scientific Name: Myctophidae
Habitat Preference: open water in the deep sea
Prey: copepods & euphausiids
Predators: deep sea fish such as barracudinas & squid

Common Name: Speckled sanddab
Scientific Name: Citharichthys stigmaus
Habitat Preference: fine sand
Prey: Mostly crustaceans, plus worms and fishes.
Predators: Diving birds like cormorants, marine mammals, crabs, and other fishes

Common Name: Spiny dogfish
Scientific Name: Squalus acanthias
Habitat Preference: gravel, sand
Prey: small fish (pelagic and benthicl), squid, crustaceans, bivalves, worms, jellyfish, salps
Predators: other dogfish, large sharks, humans

Common Name: Shiner surfperch
Scientific Name: Cymatogaster aggregata
Habitat Preference: kelp forest, rocks
Prey: Eats small crustaceans, algae, and sometimes worms and molluscs.
Predators: Birds, fishes, and marine mammals. Often caught by sportfishermen, usually from piers.

Common Name: Northern anchovy
Scientific Name: Engraulis morda
Habitat Preference: open water
Prey: Filters phytoplankton and zooplankton through its fine gill rakers.
Predators: Virtually all predatory birds, fishes (including white croakers), and mammals eat anchovies. Some pizza-lovers too. Often used as bait.

Common Name: Bat ray
Scientific Name: Myliobatis californica
Habitat Preference: sand & mud
Prey: Clams, oysters, snails, crabs, and worms.
Predators: Some humans, and possibly hammerhead sharks

Common Name: Leopard shark
Scientific Name: Triakis semifasciata
Habitat Preference: sand & mud
Prey: Bottom-dwelling fishes and invertebrates.
Predators: Humans are the main predators of adult sharks. Young ones may be vulnerable to marine mammals, adult sharks, and large fishes.

a PDF version of this file can be found in the fullcurr.pdf document (2.7mb)


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Reviewed: April 11, 2024
Web Site Owner: National Ocean Service

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