Dolphins (Primary)

DOLPHINS
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Social StudiesHistory+34-6 Grade6th,7th Grade

This lesson contains 38 slides, with interactive quizzes, text slides and 2 videos.

time-iconLesson duration is: 45 min

Introduction

Dolphins are facing a number of issues, the main ones are being caught as by catch by commercial fishing vessels, entanglement in discarded fishing nets, plastic pollution, dolphin hunts and captivity.

Instructions

During this lesson we will learn about dolphins and discuss some of the threats to dolphins and porpoises.

Time: 45 minutes

Contact: education@seashepherdglobal.org
© Sea Shepherd 2021

Items in this lesson

DOLPHINS

Slide 1 - Slide

This lesson is provided by Sea Shepherd. Sea Shepherd is a marine conservation organisation with a mission to protect the ocean and marine wildlife.  Sea Shepherd works globally on a range of issues impacting the ocean, running numerous direct action campaigns each year.  Dolphins are one species Sea Shepherd are helping to protect.
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Watch  the video

Slide 2 - Slide

During the lesson we will use these icons to identify the learning actions.
Introduction to IUU fishing and the impact of overfishing.
Dolphins and the issues impacting on them.

Slide 3 - Slide

During this lesson we will learn about dolphins and discuss some of the threats to dolphins and porpoises.

INTERACTIVE JOIN – ask students to go to www.LessonUp.app

Slide 4 - Video

Empty ocean by 2050
Scientists estimate that by 2050 the ocean ecosystem will be on the verge of collapse, empty of fish and marine wildlife, unless urgent action is taken on the issues impacting the ocean and marine wildlife.

Show this video (2.53min), which explains how important all species are to our planet.
https://www.youtube.com/watch?v=TLcA31VRlRU

Discuss the video with the class and what it means.


Illegal Fishing
Illegal fishing means that the fishermen enter the territorial waters of a country or regulated marine zone without permission or without a license for the fish they intend to catch.

They are stealing from these waters.
Over 30 species of dolphin.
Most are ocean living, five live in rivers.

Seven species of porpoises.

Slide 5 - Slide

Dolphin species
There are over 30 species of dolphin, most live in the ocean but there are five species that live in rivers.

There are also seven species of porpoises.

What are the differences
between a dolphin and
a porpoise?

Slide 6 - Mind map

Dolphins and porpoises
Ask students:
“Do know the difference between a dolphin and porpoise?”

Dolphins tend to have a more elongated beak, bigger mouths and more curved dorsal fins.

Porpoise have smaller mouths with spade-shaped teeth, the dorsal fin is more triangular shaped.  They also don’t communicate as much as dolphins.

Illegal Fishing
Illegal fishing means that the fishermen enter the territorial waters of a country or regulated marine zone without permission or without a license for the fish they intend to catch.

They are stealing from these waters.
PORPOISE

Seven porpoise species

The Vaquita is the smallest and critically endangered.

Slide 7 - Slide

Porpoise
There are seven porpoise species:
  • Dall’s porpoise
  • Harbour porpoise
  • Burmeister’s porpoise
  • Indo-pacific finless porpoise,
  • Narrow-ridged finless porpoise
  • Spectacled porpoise
  • Vaquita

The Vaquita is the smallest at 1.5m (5feet) 54kg (120lbs). It is critically endangered with less than twenty animals left. They are only found in the Gulf of California off Mexico also known as the Sea of Cortez.

Illegal Fishing
Illegal fishing means that the fishermen enter the territorial waters of a country or regulated marine zone without permission or without a license for the fish they intend to catch.

They are stealing from these waters.
WHATS IN A NAME?

Are these whales or dolphins?

➢    Killer whale (Orca)
➢    Pilot whale
➢    Melon-head whale
➢    False killer whale

Slide 8 - Slide

Whale or Dolphin
What’s in a name?

Ask students are these whales or dolphins?

  • Killer whale (Orca)
  • Pilot whale
  • Melon-headed whale
  • False killer whale

They are technically both a whale and dolphin.

Illegal Fishing
Illegal fishing means that the fishermen enter the territorial waters of a country or regulated marine zone without permission or without a license for the fish they intend to catch.

They are stealing from these waters.
CETACEAN FAMILY
Whales and dolphins are part of the cetacean family.

Two groups:
➢    Baleen whale
➢    Toothed whales - includes dolphins and porpoises.

Toothed whales - ten family groups, including:
➢    Delphindidae – dolphins.
➢    Phocoenidae – porpoises.


Slide 9 - Slide

Dolphin species
All whales and dolphins are part of the cetacean family, which is divided into two groups:
  • Baleen whales
  • Toothed whales – which includes dolphins and porpoises.  

Toothed whales have 10 family groupings, including:
  • Delphindidae – dolphins.
  • Phocoenidae – porpoises.

These species are all part of the dolphin family:
  • Killer whale (Orca)
  • Pilot whale
  • Melon-headed whale
  • False killer whale

Over 100 million tons of fish caught each year.
Dolphins are intelligent beings.

Slide 10 - Slide

Intelligent beings
Dolphins are extremely intelligent mammals. The structure of the dolphin brain is very different from that of humans. The parts that deal with thought and cognition are more complex and a dolphin's brain is relatively larger than a human's brain.

Dolphins show signs that they experience feelings of pain, fear and loss similar to the way humans do. For example, when family members are taken from a pod.

They have a similar emotional connection with family and form social bonds similar to ours.  Dolphins have been seen carrying around dead calves on their back for days, which could be interpreted as morning a loss.


Over 100 million tons of fish caught each year.
Teamwork

Slide 11 - Slide

Teamwork
Dolphins work together as a team to hunt for fish and protect each other from predators.  For example, sharks trying to take a single dolphin may find themselves under attack from the whole pod.

Dolphins are capable of using tools and solving problems.  We have been able to teach dolphins relatively sophisticated artificial languages, but we have been unable to decode their many vocalizations or language. This raises the question of which species is “smarter”—dolphins, who can learn and understand what people want of them, or humans, who still have to learn or understand what dolphins might be telling us.


Over 100 million tons of fish caught each year.
Orca

Slide 12 - Slide

Orca
Orca or Killer Whales are the largest of the dolphin family. Their original name was actually Whale Killer as they are one of the few species on this planet that will hunt and eat whales, some much bigger than Orca’s. They are considered to be a top predator in the ocean, working as team to target their prey. They are highly intelligent.

Orca’s live in family pods and hunt together. The young especially the males remain by mum’s side for most of their lives and help to baby sit younger brothers and sisters.

Orca’s can live for over 100 years.


Over 100 million tons of fish caught each year.
Bottlenose dolphins

Slide 13 - Slide

Bottlenose dolphins
Bottlenose dolphins are the most common and well known dolphins.  Bottlenose dolphins aren’t always as nice as they look, they can be pretty rough with other dolphins when they are competing for food.  They are known to form a pod of mixed species, happily interacting with other dolphin groups and even whales.


Over 100 million tons of fish caught each year.
Hectors dolphins

Slide 14 - Slide

Hectors dolphins
Hector’s dolphins are at serious risk of becoming extinct. They are found in New Zealand waters only. They have unique colouring and their dorsal fin is rounded.  

Maui dolphins are a sub-species of the Hector’s dolphin with less than 100 left.

Illegal Fishing
Illegal fishing means that the fishermen enter the territorial waters of a country or regulated marine zone without permission or without a license for the fish they intend to catch.

They are stealing from these waters.
DOLPHIN CALF

Stay with mum for 18 months to 8 years, depending on species.

Close bond between mum and calf.

Slide 15 - Slide

Dolphin calf
Dolphins are mammals giving birth to live young. Depending on the species a calf will stay with its mum for 18 months to 8 years.

Dolphin calves spend most of their early months swimming next to mum or even ride on her back. This helps it to keep up with the pod.

The bond between mum and baby is similar to ours, so the mums are sad and mourn when they lose a baby.

Slide 16 - Video

Sounds / echolocation
Dolphins have their own language, even within each group or pod they will have their own form of communication. They use unique sounds like clicks and whistles to talk to each other.

For dolphins hearing is a key sense, they use it more than sight, particular as waters can get dark and murky,

While dolphins have very good eyesight they use a sonar, known as echolocation, to locate objects. Whales and dolphins use echolocation and sounds to find their way while hunting as well as to communicate with each other.  

Using echolocation means an animal emits a sound and waits for the echo to return. These echoes help them determine what objects are around them and how close these are.

Show this video (1.15min), which shows pantropical spotted dolphins.  Listen for the clicks and whistles:
https://www.youtube.com/watch?v=kLAtfDnLCUc

Over 100 million tons of fish caught each year.
What do dolphins eat?

Slide 17 - Slide

What dolphin eats
Dolphins mainly eat small fish, crustaceans and squid. Crustacean are animals such as krill, prawns, crabs and crayfish.

Larger species like Orca, prey on whales, sharks, seals and other dolphins.

Dolphins are intelligent and have learned to hunt as a team. When they find a school of fish they circle around the fish, in order to herd them together and catch them.  When they are hunting close to shore they use their tails to kick up dirt from the seafloor to make a circle of murky water around the fish. Then as the fish try to jump out of the water over the dirty water the dolphins can catch them.

Dolphins have also been seen using tools to help them when hunting, like for instance using sea sponges on their rostrum (nose) to protect it while digging around on the seabed looking for food. This protects them from pieces of rock or broken coral.   

Over 100 million tons of fish caught each year.
Role in the ocean ecosystem.

Slide 18 - Slide

Important to the ocean
Dolphins, like whales and sharks are a very important part of the ocean they help to keep the ecosystem in balance. Dolphins help control populations of fish and squid, keeping the numbers under control, which balances the impact of each species in the ecosystem.


Over 100 million tons of fish caught each year.
Predators

Slide 19 - Slide

Predator
The two natural predators of dolphins, are orcas, who will eat other dolphin species, and sharks.

Dolphin pods work together to protect each other. Sharks can find themselves under attack from a dolphin pod, ending up having to retreat from the fight.


What do you think are the
biggest threats to dolphins
and porpoises?

Slide 20 - Mind map

What are the threats to dolphins and porpoises?”
Ask students to answer via www.LessonUp.app or discuss in classroom.

“What do you think are the biggest threats to dolphins and porpoises?”


Over 100 million tons of fish caught each year.
By-catch in commercial fishing nets.  Each year 300,000 dolphins and whales die in fishing nets.

Slide 21 - Slide

By-catch
By-catch is basically anything that gets caught in the nets and which the fishermen don’t want or cannot sell. By-catch mostly gets thrown back into the oceans as rubbish.

Given the size of fishing of commercial fishing nets, dolphins can easily become trapped. Around 300,000 dolphins and whales die each year in fishing nets.

The issue of dolphins being caught in purse seine fishing nets was raised many years ago, when the tuna fishing industries in the Pacific were caught capturing whole pods of dolphins in their nets.

Investigations into this industry uncovered footage of tuna seiners intentionally catching dolphins to find tuna, resulting in the deaths of whole pods. This investigation led to new conditions and requirements for fishing nets and how to operate nets.  

This is when the ‘dolphin safe’ logo was introduced on tins of tuna.  Unfortunately the tuna industry is still responsible for many deaths of dolphins, sharks, turtles and even whales.  



Why would dolphins be caught in nets with
tuna or other species?

Slide 22 - Open question

Why do dolphins get caught with tuna?
Ask students to answer via www.LessonUp.app or discuss in classroom.

“Why would dolphins be caught with tuna or other species?”

    Feeding on same food sources.
    Dolphins travel on the surface, where as albacore may be 20m under the surface and tuna could be 50 to 500m below the surface.


Over 100 million tons of fish caught each year.
Entangled in lost and discarded fishing gear.

Slide 23 - Slide

Entanglement in fishing gear
Fishing nets that are abandoned, lost or dumped overboard from commercial fishing vessels are also dangerous for dolphins and other animals.

They float in the oceans like death traps waiting to catch unsuspecting marine life. These nets are referred to as ghost nets.

For more information on this topic see the Lesson: Abandoned, Lost and Discarded fishing gear.

Over 100 million tons of fish caught each year.
Plastic pollution.

Slide 24 - Slide

Marine debris
Plastic pollution concerns all marine wildlife.  Each year over 12 million tonnes of trash finds its way into the ocean.

Ask students why they think this is an issue for dolphins?

They can’t always distinguish the difference between rubbish and food, when they do. It often is too late and they might have already swallowed it, or have gotten entangled, unable to free themselves.

Ocean pollution kills hundreds of thousands of marine animals each year.


Illegal Fishing
Illegal fishing means that the fishermen enter the territorial waters of a country or regulated marine zone without permission or without a license for the fish they intend to catch.

They are stealing from these waters.
NOISE POLLUTION

Ships sonar.

Shipping noise from vessels, ports and shipping lanes.


Noise travels 4 times faster under water and further.

Slide 25 - Slide

Noise pollution
Dolphins and whales use echolocation, which is like the sonar that we use on boats.

This means that the sonar on some boats, like navy ships, can interfere with a dolphin’s natural sonar.  Which means it can stop them from being able to find their way or hunt. This can result in these animals becoming disorientated and sometimes beaching themselves.

Noise pollution from shipping
Sound travels 4 times faster under water and it travels further, so imagine the noise coming from a port or shipping lane. Imagine living in a constantly noisy environment and how stressful that might be for marine wildlife.

All this noise may reduce the ability of dolphins and whales to communicate with each.

Over 100 million tons of fish caught each year.
Ship strikes.

Slide 26 - Slide

Ship strikes
Shipping is the main way that goods are transported around the world. Up to 90% of cargo is transported over water.

Increases in shipping over the last 50 years, has led to two issues.  The first we have already talked about, noise pollution. The second is ships hitting marine wildlife.  

For dolphins the main threat comes from smaller faster vessels, such as speed boats and jet skis.

There are laws in place that restrict the speed of vessels in areas close to shore, to protect dolphins and whales, but not everyone respects them.


Over 100 million tons of fish caught each year.
Oil spills and chemical pollution.

Slide 27 - Slide

Oil spills
Another issue with a huge impact on the health of our ocean are oil disasters and toxic waste.  

These can have a devastating impact on marine ecosystems and take decades for the area to start to recover.

Some 40% of oil produced is shipped around the world in tankers and over the years there have been a number of accidents with oilrigs and tankers.

In the Gulf of Mexico in 2010 an oilrig doing exploratory drilling had a blowout, resulting in oil leaking into the surrounding ocean for 3 months.

The chemicals used to disperse the oil from the ocean surface are also toxic, with some even causing cancers. They can also cause the oil to be dropped to the seafloor, coating everything in a layer of oil, killing everything on the seabed.

Exposure to the oil and chemicals can have long term impacts for the health of marine animals like dolphins and whales, including birth defects in their calves.


What other chemicals might
be ending up in the ocean?

Slide 28 - Mind map

What other chemicals end up in the ocean?
Ask students to answer via www.LessonUp.app or discuss in classroom.

“What other chemicals might be ending up in the ocean?”
  • Household chemicals.
  • Medications
  • Chemicals from agriculture run off.
  • Pesticides and weed killers used in gardens.

Over 100 million tons of fish caught each year.
Dolphin hunts.

Slide 29 - Slide

Dolphin hunts
There are a number of places around the world where dolphins are hunted.

The main reasons for the hunts are:
  • The dolphins are caught and used for bait to catch fish and sharks. This happens in places like Peru, where it is illegal to kill them, but fishermen kill thousands of dolphins each year for bait to catch sharks.
  • For meat for human consumption. This happens in Japan, Faroe Islands, Greenland.
  • To be taken into captivity for entertainment. This happens for instance in Taiji, Japan.
  • For their teeth.  In the Solomon Islands dolphins have been killed for their teeth, which are used as decorations and as a form of currency.

Over 100 million tons of fish caught each year.
Dolphin captivity.

Slide 30 - Slide

Captivity
The fisherman in Taiji, Japan make a lot of money for capturing dolphins and selling them to marine parks/aquariums. The marine parks then make money by having the dolphins entertain visitors.

Who doesn’t love watching dolphins swim and jump around in the water, but captivity is not a happy place for any dolphins, regardless of whether it is bottlenose dolphins or orca’s.

Why do you think a dolphinarium might be a sad place for a dolphin to be?
  • Dead fish rather than fresh – not as healthy and not stimulation to hunt.
  • This dead fish is full of medications as dolphins in captivity can get very sick and very depressed.
  • Taken from their family groups – how would you feel being separated from your family & friends?
  • Put into tanks with foreign animals that may not communicate the same way. Think how scary it would be being stuck in a foreign country not speaking the language.
  • Size of the tanks –Instead of open oceans they spend the rest of their lives in a tiny pool or pen where they can only swim around and around in circles.
  • No stimulation – they rely on echolocation and sounds – Concrete walls prevent sound traveling, no fish to catch, ocean currents or waves.
  • Pools and chemicals in environment – their water is re-used and dosed with chemicals to keep it clean.
  • They are kept hungry and forced to learn tricks for food just to entertain us humans.

For more information see the Lesson – Dolphin Captivity.

How do you think you can help
protect dolphins from some
of the issues with have discussed?

Slide 31 - Mind map

How can we protect dolphins?
Ask students to answer the following question using www.LessonUp.app or discuss in the classroom.  

“How do you think you can help protect dolphins from some of the issues we have discussed?


Illegal Fishing
Illegal fishing means that the fishermen enter the territorial waters of a country or regulated marine zone without permission or without a license for the fish they intend to catch.

They are stealing from these waters.
PROTECTING DOLPHINS
➢    Don’t support captivity.
➢    Help to shutdown dolphinariums.
➢    Think about noise pollution if out on the water on a boat and be careful to watch for dolphins so they don’t get hit.
➢    Reduce demand for fish, particularly from industries with high levels of dolphin by-catch.
➢    Help fight plastic pollution – reduce your use of single use plastics or join in beach clean ups.

Slide 32 - Slide

Protecting dolphins
How can help protect dolphins:
  • Don’t support captivity.
  • Help to shutdown dolphinariums.
  • Think about noise pollution if out on the water on a boat and be careful to watch for dolphins so they don’t get hit.
  • Reduce demand for fish, particularly from industries with high levels of dolphin by-catch.
  • Help fight plastic pollution – reduce your use of single use plastics or join in beach clean ups.  

These areas can be expanded as classroom discussions or research projects on ways students can help in each area.  


Name five issues impacting on dolphins?

Slide 33 - Open question

Ask students to answer the following question using www.LessonUp.app or discuss in the classroom.  

“Name five issues impacting dolphins?”


Why are so many dolphins and other marine species caught by commercial fishing nets?

Slide 34 - Open question

Ask students to answer the following question using www.LessonUp.app or discuss in the classroom.  

“Why are so many dolphins and other marine species caught by commercial fishing nets?”


Write down three things you have learned?

Slide 35 - Open question

What did you learn?
Ask students to answer the following question using www.LessonUp.app or discuss in the classroom.  

“Write down three things you have learned?”



Write down one thing you didn't understand?

Slide 36 - Open question

What don’t you understand?
Ask students to answer the following question using www.LessonUp.app or discuss in the classroom.  

“Write down one thing you didn’t understand?”


Slide 37 - Slide

Sea Shepherd Case Studies cover a number of Sea Shepherd campaigns and show video of some of our work to protect dolphins. These can be used to enhance the learning experience from these lessons.

www.seashepherdglobal.org

Slide 38 - Slide

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