9-12 Marine Mammals

Section 1: Welcome to the Activity

Focus Question

How can we distinguish between marine mammal species? What is the distribution of marine mammals?


Activity Synopsis

Students will use a dichotomous key to distinguish between marine mammal species based on external characteristics. Then they will learn about the worldwide distribution of different marine mammal species by plotting and analyzing latitude and longitude.


The learner will be able to:
  • Use a dichotomous key to determine marine mammal species
  • List the three orders of marine mammals and provide a species from each order
  • Describe the difference between suborder Mysticeti & suborder Odontoceti
  • Explain two unique adaptations of marine mammals that allow them to live in the water
  • Plot navigation data using latitude and longitude

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Section 2: Standards

Biology:  H.B.1A.4, H.B.1A.5, H.B.1A.6, H.B.1A.7, H.B.1A.8, H.B.6A.1, H.B.6C.1

* Bold standards are the main standards addressed in this activity

Biology Performance Indicators

  • H.B.1A.4   Analyze and interpret data from informational texts and data collected from investigations using a range of methods (such as tabulation, graphing, or statistical analysis) to (1) reveal patterns and construct meaning, (2) support or refute hypotheses, explanations, claims, or designs, or (3) evaluate the strength of conclusions.
  • H.B.1A.5   Use mathematical and computational thinking to (1) use and manipulate appropriate metric units, (2) express relationships between variables for models and investigations, and (3) use grade-level appropriate statistics to analyze data.
  • H.B.1A.6   Construct explanations of phenomena using (1) primary or secondary scientific evidence and models, (2) conclusions from scientific investigations, (3) predictions based on observations and measurements, or (4) data communicated in graphs, tables, or diagrams.
  • H.B.1A.7   Construct and analyze scientific arguments to support claims, explanations, or designs using evidence and valid reasoning from observations, data, or informational texts.
  • H.B.1A.8   Obtain and evaluate scientific information to (1) answer questions, (2) explain or describe phenomena, (3) develop models, (4) evaluate hypotheses, explanations, claims, or designs or (5) identify and/or fill gaps in knowledge. Communicate using the conventions and expectations of scientific writing or oral presentations by (1) evaluating grade-appropriate primary or secondary scientific literature, or (2) reporting the results of student experimental investigations.
  • H.B.6A.1   Analyze and interpret data that depict changes in the abiotic and biotic components of an ecosystem over time or space (such as percent change, average change, correlation and proportionality) and propose hypotheses about possible relationships between the changes in the abiotic components and the biotic components of the environment.
  • H.B.6C.1   Construct scientific arguments to support claims that the changes in the biotic and abiotic components of various ecosystems over time affect the ability of an ecosystem to maintain homeostasis.

South Carolina College and Career Standards for ELA
Inquiry (I) – 2.1
Communications (C) – 1.1

Section 3: Background

Key Points will give you the main information you should know to teach the activity. 

  • Marine mammals are endothermic (warm blooded) vertebrate animals that give live birth, breath through lungs, have hair and feed young with milk.
  • Marine mammals include animals from the
    • Order Cetacea: suborder Mysticeti (baleen whales: humpback whale) & suborder Odontoceti (toothed whales: orca)
    • Order Sirenia (sea cows: manatee)
    • Order Carnivora: suborder Pinnipedia (flipper-footed: seals/sea lions) & suborder Fissipedia (paw-footed: sea otters/polar bears)
  • There are over 100 species of marine mammals found throughout the world. The list is constantly changing as new species are discovered or species become extinct.
  • Marine mammals are found in every type of water (salt water, fresh water and brackish water) and all around the world.
  • Protecting these animals involves understanding their worldly distribution and feeding.

Detailed Information gives more in-depth background to increase your own knowledge, in case you want to expand upon the activity or you are asked detailed questions by students.

Marine mammals, like all mammals, are vertebrates (have a backbone) with the following characteristics:

  • Warm-blooded
  • Breath air
  • Give live birth
  • Nurse young with milk
  • Have hair

*What separates marine mammals from other mammals is that they live in or by the ocean.

Marine mammals are endothermic or warm-blooded. This means that their body temperature is kept at a constant and not controlled by its environment. They are air breathers, using a lungs to breathe. Some species of marine mammals have a blow hole/s, an adaptation that allows them to breathe more efficiently at the surface of the water. Marine mammals have internal fertilization, resulting in a baby through live birth that was nourished by a placenta while in the womb. Mother marine mammals will nurse their young and take care of them for up to a few years depending on the species. All marine mammals live in the ocean with a few exceptions, such as the river dolphins. Some species, like the bottlenose dolphin, also have the ability to live in brackish water, where salt and fresh water mix. Some marine mammals like those within the order Carnivora have hair for their entire life, while others like order Cetacea may only have hair as a newborn that quickly falls out.


Taxonomy is the division of biology that systematically classifies organisms. The levels, or taxa, of taxonomy are Kingdom, Phylum, Class, Order, Family, Genius and Species. Marine mammals are found in the Kingdom Animalia, Phylum Chordata and Class Mammalia. There are over 5000 species with 26 orders in the Class Mammalia. Marine mammals are mammals that spend their lives in saltwater (a few species found in rivers). There are over 100 species of marine mammals within 3 orders. Taxonomists don’t all agree on the exact placement within the taxonomic structure of these animals so if can get quite confusing. Marine mammals also don’t all have a common ancestor so what unites them is their reliance on saltwater for food and shelter. We are going to use the following taxonomic structure to explain marine mammals. You may find this information organized differently or with slightly different names in other resources.

Marine mammals include animals from three orders: Cetacea, Carnivora, Sirenia. The order Cetacea includes the whales, dolphins and porpoises which includes about 89 living species. This order is divided into two suborders: Mysticeti and Odontoceti. Mysticeti are baleen whales such as humpback and North Atlantic right whales. Odontoceti are toothed whales such as dolphins and orcas. Order Carnivora is divided into many suborders including over 280 placental mammal species. Two of the Carnivora suborders have marine mammals including about 35 species. Those are Pinnipedia or ‘flipper-footed’ that includes seals and sea lions and Fissipedia or ‘paw/pad-footed’ including polar bears and sea otters.  The order Sirenia or ‘sea cows’ is comprised of two aquatic, herbivorous families, the Dugongs and Manatees, and there are just 4 living species.

Order Cetacea (89 species)

  • Suborder Mysticeti (baleen whales: humpback whales)
  • Suborder Odontoceti (toothed whales: dolphins)

Order Carnivora (280 total, 35 marine mammal species)

  • Suborder Pinnipedia (flipper-footed: seals/sea lions/walrus)
  • Suborder Fissipedia (paw-footed: sea otters/polar bears)

Order Sirenia (4 species)

  • Manatees
  • Dugongs

There are around 100 species of marine mammals found throughout the world. The list is constantly changing as new species are discovered, reclassified or become extinct. Marine mammals can be found in all of the world’s oceans and in all types of water, but the vast majority live in saltwater.


Marine mammals are well adapted to life in the ocean. They have many behavioral and physical adaptations (body parts) that allow them to successfully live in the ocean. These physical adaptations help them live in cold water, hold their breath for long periods of time, thermoregulation, swim fast, conserve water and hunt successfully in cold, dark or turbid (murky) waters. Some behavioral adaptations include echolocation, site specific feeding behaviors and adapted ways to sleep, or rest, while staying active.

Thermoregulation – One way that most marine mammals maintain their body temperature is through a thick layer of blubber. Blubber is a unique, thick layer of connective tissue found right below the skin and contains lipids (fats) and collagen (proteins). Blood vessels within blubber constrict in cold water, which helps conserve heat. Another way all marine mammals stay warm is through countercurrent heat exchange, where heat from the arteries is transferred to the veins. The arteries and veins are close together so heat can be transferred. Finding an equilibrium is a goal of nature so heat travels from high to low zones; therefore, heat from a warm artery will be transferred to a cool vein that is close-by. Arteries bring warm oxygen-rich blood from the heart to the rest of the body whereas veins bring cooler blood back to the heart to receive more oxygen.

Breathing adaptations – One would think marine mammals would have large lungs to hold more air, but in reality most marine mammals have small lungs that work more efficiently. When humans breathe we exchange 10-20% of the oxygen in our lungs in a single breath. Compare this to bottlenose dolphins who exchange 80% of their oxygen in a single breath. Additionally, marine mammals have high blood volume and more red blood cells, which increases their oxygen carrying capacity. Deep diving marine mammals have an amazing adaptation that allows them to survive under immense pressure for example the Sperm Whale can dive up to 2,250 meters where its ribs and lungs actually collapse under pressure.

Swimming adaptations – Another breathing adaptation that creates efficient swimming is the blowhole found on cetaceans. This allows cetaceans to exchange gases at the surface of the water quickly and efficiently when swimming. The blowhole is located on the dorsal (back) side of the animal. When their dorsal side breaks the water they can breathe while keeping most of their body underwater. Odontoceti species have one blowhole while Mysticeti species have two blowholes. All marine mammals also have a hydrodynamic body plan with modified appendages that reduce drag and increase propulsion within the water.

Water conservation – Most marine mammals do not drink water as other animals do. Instead they receive freshwater from the food they eat as well as from their blubber supply. Another adaptation that reduces the amount of freshwater needed are their kidneys.  Marine mammal kidneys are adapted to make very salty urine, it is saltier than the saltwater they live in.

Sensory adaptation – Suborder Odontoceti, or toothed whales, communicate and locate their prey in a unique way. They use echolocation to speak to each other and also to hunt. In echolocation, these marine mammals send out sound waves which hit and come back to the marine mammal. This echo of the original sound wave is how they can tell how far away a prey item may be. Marine mammals use their melon, a part of their forehead, to focus the outgoing sound waves towards a specific area while their lower jaw acts as the receiving dish for returning sound waves. Pinnipeds use their very sensitive whiskers for exploring and hunting. The whiskers pick up on small vibrations in the water that helps the pinniped find its food.


Marine mammals can be found in every ocean of the world. The second class period activity will focus on the worldwide distribution of marine mammals by highlighting the following 10 species (in alphabetic order) and their typical range and habitat.

  • Amazon river dolphins
  • Bottlenose dolphins
  • California sea lions
  • Hawaiian monk seals
  • Humpback whales
  • Narwhals
  • North Atlantic right whales
  • Orcas
  • Spinner dolphins
  • Vaquitas

Amazon river dolphins (Inia geoffrensis): Found in freshwater rivers and lakes in the Amazon River basin in South America. Another name for these dolphins is boto. These dolphins are very shy and sightings are rare. There are multiple species of river dolphins found in the tributaries of the Amazon and Orinoco rivers. Amazon river dolphins are the largest of freshwater dolphins.

Amazon River dolphin range (light blue) from Voices in the Sea

 Bottlenose dolphins (Tursiops truncatus): The most common dolphin species found off the east coast of the USA. Bottlenose dolphins are found in tropical to temperate waters around the world and are found in the Pacific, Atlantic, and Indian Oceans. Since they have a global habitat and usually live off the coast, this species has been extensively studied.

Bottlenose dolphin range (light blue) from Voices in the Sea

California sea lions (Zalophus californianus): Found off the western coast of North American, ranging from the Vancouver Islands all the way south to Baja California in Mexico. There is a separate and distinct California sea lion population found on the Galapagos Islands. These pinnipeds are very playful and agile mammals that have external ear flaps and rear flippers they use to walk, or move around, on land. These physically adaptations make them different than seals. California sea lions face many dangers in the wild including malnutrition, diseases, entanglements and even mutilation such as gunshot wounds.

California sea lion range (light blue) from Voices in the Sea

Hawaiian monk seals (Neomonachus schauinslandi): and the most tropical seal species found in the world. Unlike a sea lion, seals do not have external ear flaps nor do their rear flippers rotate to help an animal walk on land. It is estimated that there are only 1,300 individuals left on the Hawaiian Archipelago. These pinnipeds are nocturnal (hunt at night) hunters and eat a diverse diet of seafood from octopuses to lobsters to fish. Mother Monk seals will stop eating for up to 6 weeks to take care of their newborn pup on land.

Hawaiian Monk Seal range (light blue) from Voices in the Sea

Humpbacks whales (Megaptera novaeangliae): Found throughout the world’s oceans and migrate depending on breeding and feeding seasons. One well known and documented humpback whale migration is located in the North Pacific Ocean, between Hawaii and Alaska. The humpback whales spend summer in the northern areas, feeding off of the abundant food available due to upwelling. Upwelling is where the top layer of water is pushed offshore by strong winds, this cold water falls to the bottom of the ocean, pushing up the nutrients from the deep. During the fall they migrate back to tropical waters of Hawaii for mating, birthing and wintering. There are three documented humpback whale stocks (breeding groups) that migrate in this region of the world. The eastern stock stays close to the western coast of the USA and Mexico. The central stock migrates between Hawaii and Alaska. The western stock can be found migrating between the Aleutian Islands and Japan.

Humpback range (light blue) from Voices in the Sea

Narwhals (Monodon monoceros): Found in the Arctic Ocean off the coast of Canada, Russia, Norway and Greenland. Most have a long tooth that protrudes from their head and can grow up to 10 feet long. Narwhals are deep diving marine mammals, reaching depths of up to a mile and a half underwater. During their dives, they search for prey items such as squid, fish and shrimp. A current threat for narwhals is increased boat traffic, underwater noise and pollution due to oil and gas development in the Arctic Ocean.

Narwhal range (light blue) from Voices in the Sea

North Atlantic right whale (Eubalaena glacialis): Another rare species of marine mammal with approximately 450 individuals left in the world. They do not have a dorsal fin so identifying individuals is done by their unique patches of callosities, or areas of raised skin. Each whale has their own pattern of callosities, which appears white due to whale lice. North Atlantic right whales feed off the coast of New England and then migrate 1,000 miles to the south to the warm waters off the coast of South Carolina, Georgia and Florida for breeding season.

North Atlantic Right Whale range (light blue) from Voices in the Sea

Orcas (Orcinus orca): Widely distributed marine mammals and inhabit every ocean in the world. They are typically found in cooler, more bio-productive water where upwelling occurs. These nutrients then act as a fertilizer for plankton, the base of the food chain, which then creates a rich food web. The orcas are intelligent, apex predators who are attached to these rich food webs. Another common named used for orcas is Killer Whale.

Orca range (light blue) from Voices in the Sea

Spinner dolphins (Stenella longirostris): Very aerobatic marine mammals, who can be seen leaping and spinning out of the water. They are found in tropical and sub-tropical waters around the world. As with other marine mammals, spinner dolphins are becoming bycatch as an untargeted species in fishing gear. Yellowfin tuna associate with certain dolphin species such as spinner dolphins. In the 1960s fisherman would spot the group of spinner dolphins to find a school of tuna. During the capture of the tuna, many dolphins were injured or killed. Today, the fishing methodology has changed resulting in fewer bycatch dolphins, although some illegal activity is still a challenge for these marine mammals.

Spinner dolphin range (light blue) from Voices in the Sea

Vaquitas (Phocoena sinus): The smallest marine mammal in the world. They are also the most critically endangered, with fewer than 15 individuals left in the world! Multinational efforts are underway that are desperately trying to save this species from extinction. The Vaquita’s biggest challenge are the illegal gillnets that entangle and kill many untargeted species. Unfortunately, human care is not a conservation option for this critically endangered species so efforts need to be made to protect them in the wild.

Vaquita range (light blue) from Voices in the Sea

Section 4: Procedures

Class Period 1 – Marine Mammal Species

Class Period 2 – Marine Mammal Distribution

Class Period 1 – Marine Mammal Species

1. Start by using the Activity Presentation to go over general information.

2. Make sure all students understand the characteristics of a mammal (vertebrates, air breathers, warm-blooded, live birth, fur and milk for young).

3. Go a step further to explain to them that marine mammals are mammals that live in saltwater (a few live in freshwater) and are divided into three Orders (Cetacea, Carnivora and Sirenia) and explain the ways in which the three orders differ from one another.

4. Introduce the many unique adaptations (physical or behavioral trait that helps an animal survive) of marine mammals.

  • Ask the students why marine mammals have so many varied adaptations and which one is the most important. Have them answer these journal prompts in their journal/notebooks.

5. After they complete the journal prompts, review the external anatomy of marine mammals. Let the students know that each species is different and this can be seen by looking at the external features of the marine mammal.

6. Give each student one marine mammal species from the list on slide 13 (bottlenose dolphin, orca, harbor seal, sea lion, North Atlantic right whale) and draw it in their journal, labeling its physical features and their corresponding adaptations (for example – melon for echolocation). Students will be able to pick physical features and adaptations from a word bank on slide 13.

7. Briefly go over a few of your student’s drawings, picking a different marine mammals each time and emphasize the physical traits and adaptations. Explain that the physical traits help distinguish between species. Pictures can be found on slide 14.

8. Let the students know that they are going to use pictures of marine mammals to distinguish between species using a dichotomous key. Give each student a Marine Mammal Dichotomous Key.

9. Go over how to use a dichotomous key with the students (this should be a review from middle school). Tell them it’s like a choose your own adventure book, where they will be offered 2 options and by picking the right answer it will take them to another 2 options and so forth until they get to the final answer (the correct species).

10. To practice using a dichotomous key read the script below about a marine mammal sighting (told by a fisherman).

“Well, here is what I can tell you about the sighting. It was a sunny, brisk day out there on the Atlantic Ocean. We were out fishing for some grouper when out of nowhere a massive figure came up to the surface. It was very odd because it didn’t have teeth, at least teeth you would see on a dolphin. And another thing that was strange was the animal didn’t have a fin on the back- it didn’t have a dorsal fin! It was a very odd animal and we couldn’t figure it out.”

This would be a way for student to use the dichotomous key to figure out that the fishermen saw a North Atlantic Right Whale. (1. Does you mammal have teeth? If No- go to 10; 10. Does your mammal have a dorsal fin? If no, you have a marine mammal J = North Atlantic Right Whale)

11. Now that your students have an idea on how to use the dichotomous key. Give each student (or a small group of students) a set of Species Identification Cards. When they figure out the marine mammal species, have them label it by letter.

  • You could set this up as a lab by cutting the cards apart, laminating them and setting them around the classroom making 10 stations (each with a Dichotomous Key). Then students could rotate through and record their answers on a piece of paper numbered 1-10.
  • You could also reinforce knowledge with a game by splitting class into two teams and one team will hold up the species identification card and the other team will have 30 seconds to work together to identify it. A bonus point can be given if a unique, un-used adaptation (behavioral or physical) can be given.

12. Once they are done, check their answers as a class using the answer key.


Class Period 2 – Marine Mammal Distribution

1. Now that the students have a general understanding of the characteristics of marine mammal species let’s move on to their habitat distribution by continuing with the intro presentation (slides 16 to end).

2. Explain that the students will learn about 10 species of marine mammals and where they can be found living in the world. The 10 species are:

  • Amazon river dolphin
  • Bottlenose dolphin
  • Narwhal
  • North Atlantic right whale
  • California sea lion
  • Hawaiian monk seal
  • Humpback whale
  • Orca
  • Spinner dolphin
  • Vaquita

3. Ask them to tell you what type of water marine mammals live. Answer, all types of water (fresh, salt and brackish).

4. Let them know that they are going to plot the latitude and longitude of marine mammal species. The location and given description will help them choose the right species.

5. Review latitude and longitude (use Latitude and Longitude of the World on presentation to help). Plot a couple points as a group so students understand how plotting latitude and longitude works.

6. Group students in pairs and give each pair a Marine Mammal Distribution Worksheet. Each worksheet has 10 coordinates as well as a world map to plot the locations. The coordinates represent different locations the species of marine mammals are found throughout the world.

7. Have students plot all 10 points making sure to put the number next to each spot.

8. Once they are done, use slides 19-28 on the presentation to help them determine which number goes with which marine mammal. Note, they will need to use the description to help.

9. Have them answer this open-ended question on their worksheet: Why do we need to learn about the worldwide distribution of marine mammals? Go around the class to hear each groups’ answers.

10. Afterwards explain that it’s important that we know and are able to protect these habitats as many marine mammals are threatened or endangered species.  We need to understand where they go (to protect their environment) and what they eat (to protect their food sources). This knowledge is an important part of fishing regulations and permitting areas.

  • Is there an issue that some marine mammal species face as they move between boundaries/oceans? Who protects them? What other issues could affect them? Could this affect other species besides marine mammals, if so, which ones?
  • How do we use longitude & latitude on a daily basis?
  • What marine mammal adaptations have inspired human technological advances? Could introduce biomimicry (echolocation – sonar).

Section 5: Assessment

Give students Marine Mammal Assessment Worksheet and the Marine Mammal Dichotomous Key. They should be able to determine the two species using the dichotomous key as well as match three marine mammal species to a specific ocean/region.

Scoring rubric out of 100 points

Correctly name the 2 marine mammal species: 10 points each (20 total)
Adequately explains why they choose that species: 10 points each (20 total)
Correctly lists latitude and longitude points for 4 different points: 10 points each (40 total)
Correctly describes why scientists need to understand: 20 points

Section 6: Cross-Curricular Extensions

Social Science Extension

Watch this TEDed that discusses Tragedy of the Commons https://www.youtube.com/watch?v=CxC161GvMPc

  • How can you connect marine mammals to the Tragedy of the Commons?


STEAM Extension

Have students create (draw/collage/paint/etc.) a world’s ocean map with a different marine mammal species in of the 5 oceans.


STEAM Extension

Have groups create a 3D model using appropriate props to depict the humpback whale’s migration from Hawaii to Alaska. Within their model they should also show one hazard the whale may face during migration.

Section 7: Resources

Teacher and Student Reference Websites

Animal Diversity Web: Mammals
This site gives a great background on the Class Mammalia.

The Marine Mammal Center
A great place to read over the taxonomic structure of marine mammals.

Voices in the Sea
Great site for species information, sounds/calls, videos, games and more. Their distribution maps are amazing and referenced within this activity.

The Marine Bio Conservation Society
Lots of background information on marine mammals.

Sea Grant Alaska
List of marine mammals adaptations.

Distance Learning Opportunities

Pacific Marine Mammal Center

Alaska SeaLife Center

Online Curricula

Exploring Our Fluid Earth, University of Hawaii

Recommended Pre-visit Activity