Long Way Education

By Eman Abdallah Kamel

Eman is a writer and engineer. She likes searching for and writing about animals and plants, among many other topics.

Dolphins are amazing aquatic animals. In this article, you will learn about dolphins, their facts, behaviour, characteristics, 6 endangered species, threats, and tips to save them from extinction.

Dolphin

A dolphin is a marine animal that belongs to the whale family. Because they are mammals and not fish, dolphins have warm blood and can regulate their body temperature. They have lungs and breathe through a single nostril called the blowhole, located on the top of their head.

Dolphins’ skin is typically a mix of black, white, and grey and is soft and elastic. The dolphin has two fins on its sides and a triangular fin on its back. Unlike fish, the dolphin’s tail is horizontal. Dolphins live in seas, oceans, and rivers in groups called dolphin pods. Some groups of dolphins prefer to live in coastal areas, while others live in shallow waters far from the coast or further out to sea.

There are about 40 species of dolphins, the largest of which is called the orca (Orcinus orca), or killer whale, while the smallest is called the Hector’s dolphin.

To learn more about rare dolphins, visit the dolphin species spotlight.

Characteristics and Behavior

• Like all mammals, dolphins give birth; they do not lay eggs. They are warm-blooded.
• Dolphins have lungs to breathe air, and they are all vertebrates. Dolphins are born with hair on their upper jaw to keep them warm in cold areas, but it falls off about 2 weeks after birth. Dolphins use the mammary glands of the female to nurse their young. Adult dolphins have blubber (the fat of sea mammals) to act as an insulator layer.

What are mammals?
Mammals are a group of vertebrate creatures such as cats, mice, dogs, deer, monkeys, bats, dolphins, whales, and humans.

• The dolphin comes to the surface, opens its blowhole, exhales air that can be seen as water vapour, and takes a fresh breath. The dolphin controls the muscles in the blowhole. It learns to adjust the blowhole to open above the water and close before returning to the bottom. Baby dolphins are taught how to adjust their breathing and swimming patterns appropriately.

• Dolphins can sleep by resting one-half of their brain at a time. They must be able to come to the surface to breathe and to be alert in case of danger. Dolphins sleep with one eye open at all times. Sleeping dolphins are usually in small groups. The dolphins also swim slowly when they are sleeping.
• They feed on fish, shrimp, and squid. Dolphins have teeth that allow them to grab and hold fish and other prey. They swallow their prey whole and do not chew their food as we do.
• Dolphin pod (group of dolphins) structures include nursery pods (groups of mothers with their young, sometimes with a few males, and also with the elders whom they protect), juvenile pods (groups of young adults), and male pods (small groups of males that travel together and work cooperatively).

Did you know?
Some dolphins mate within their groups but never with their relatives. This occurs in species with large groups; in smaller groups, males leave the group to mate and then return to their family group.

• Dolphins play together and work together while hunting. The dolphins work together to make a mud ring to catch fish. Then, some dolphins in the group wait outside the ring for fish that try to escape and swallow them as a snack. Dolphins also help their species and other species without any benefit to themselves.
• Dolphins can communicate using a series of clicks, whistles, and squeaks. Dolphins also show their emotions; they show sadness and joy.
• Dolphins can travel 40 miles daily, and larger dolphins, orcas, can travel 100 miles daily.

The Endangered Dolphins and Threats

According to the International Union for Conservation of Nature, some species of dolphins are threatened with extinction.

• Gangetic River Dolphins
• Atlantic Humpback Dolphins
• The Irrawaddy Dolphin
• Hector’s Dolphin
• Pink Amazon River Dolphin
• The Chinese River Dolphin or Baiji

1. Gangetic River Dolphins

Gangetic River dolphins are endangered, with only a few thousand mature individuals remaining in the wild.

Ganges River dolphins and humans prefer the river where fish are abundant and the water current is slower. Because of this, humans are catching fewer fish, and dolphin deaths from unintentional entanglement in fishing nets have increased. The Ganges River dolphins are still hunted for meat and oil.

Pollution is another cause of habitat degradation. Every year, 9,000 tons of pesticides and 6 million tons of fertilizer are used in the river’s surroundings. High pollution levels have the direct ability to kill dolphins and prey while destroying their habitat.

2. Atlantic Humpback Dolphins

The International Union for Conservation of Nature classifies the Atlantic humpback dolphin as critically endangered, with only an estimated 1,500 individuals remaining in the wild.

Threats to Atlantic humpback dolphins include deliberate fishing, coastal development, and human noise. Bycatch in artisanal gillnets is the primary threat to this species.

3. The Irrawaddy Dolphin

The Irrawaddy Dolphin was assessed for the IUCN Red List of Threatened Species.

Did you know?
In 2004, WWF and TRAFFIC, the world’s largest wildlife trade monitoring network, supported a ban on the international live trade of Irrawaddy dolphins under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).

4. Hector’s Dolphin

The smallest marine dolphin in the world, the Hector’s dolphin, is native to New Zealand and is considered endangered.

Hunting, toxoplasmosis, oil and gas exploration, boat strikes, mining, tourism, and noise pollution are some threats facing these dolphins.

5. Pink Amazon River Dolphin

The Amazon River or pink dolphin is listed as endangered; it is found in most of the Amazon and Orinoco river basins.
Threats facing this type are pollution of rivers and lakes, and dam collapses.

6. The Chinese River Dolphin or Baiji

The Yangtze River in China was once home to the baiji. The number of baiji declined dramatically, and they eventually disappeared from the river. The IUCN Conservation Status is Endangered (possibly extinct).

Baijis live largely in the mainstream of the middle and lower reaches of the Yangtze River and two large lakes connected to it, Dongting and Bo Yang. Baijis were often seen near sandbars, where tributaries enter the main river and deposit sediment. These sandbars create eddies in the water that are rich in nutrients and attract fish. Baijis and anglers prefer these habitats for fishing.

Did you know?
The baiji is the only member of the Lipotidae family of mammals because it possesses special traits that no other whale or dolphin species have. The stomach is divided into three sections; this is a unique feature of the anatomy of the baiji. In addition, the baiji’s extinction signifies the end of the ancient family Lipotidae.

Conversation Efforts

Many international efforts have been made to save dolphins from extinction, such as

Every year, the Cambodian Mekong Dolphin Conservation Project conducts at least two surveys of the Irrawaddy dolphin population in the Mekong River. To address threats, some agencies and local people have collaborated to address the impacts of climate change in the Mekong River Basin through habitat restoration and infrastructure improvements.

Also, the World Wildlife Fund (WWF) supports river dolphin surveys to assess the condition and vulnerability of Amazon river dolphins and their habitat. In addition, WWF supports studies investigating how dams affect the size and distribution of dolphin populations.

The Ministry of Environment and Climate Change of the People’s Republic of Bangladesh has prepared an action plan for two species of dolphins: the Ganges River Dolphin and the Irrawaddy Dolphin in Bangladesh. These two species were selected because they inhabit different geographic regions in the river and coastal waters. This action plan will apply to other cetaceans living in these habitats. The plan aims to reduce the unprecedented human interference in dolphin habitats and the dependence of “ecosystem inhabitants” on dolphins.

Your Part in Helping Save Dolphins

To conserve the environment from pollution and protect dolphins and other sea creatures from extinction, try following the next tips:

1. Avoid dropping bags and plastic bottles into the water.
2. Donate your time to remove litter from beaches.
3. Try not to make any noise on the beaches.
4. Avoid the illegal dolphin trade.
5. Organizing beach tourism and not driving boats randomly in the water, which collides with dolphins and causes them injury or death.
6. Follow fishing regulations to avoid the bycatch of dolphins.
7. If we want to address global climate change, we all need to do our part by reducing our carbon footprint, reducing environmental pollutants, and increasing tree planting.

Sources

• stgilesstgeorgesacademy.co.uk-Dolphins-Reading-Comprehension.pdf
• All about dolphins.
• Facts about orcas (killer whales)
• What is a mammal?
• Bottlenose Dolphin
• Ganges River Dolphin
• Atlantic Humpback Dolphin
• Irrawaddy Dolphin
• Hector’s dolphin
• ifaw.org/animals/dolphins
• Studying the health of dolphins after pollution
• Conservation Action Plan for Ganges River Dolphin and Irrawaddy Dolphin of Bangladesh 2021-2030…pdf

©Eman Abdallah Kamel, 2024

Latest Articles

• The Story of The Prophet Moses
• Glass Fiber: Manufacturing Process, Types, and Properties
• Denim Fabric Dyes
• Denim: Manufacturing Process, Properties, and Types
• Surah Al Qadr: Explanation and Benefits

LongWayEducation

The Long Way Education Site path is based on self-learning. Here, you will learn about science, education, and religion. You will also learn about fiber and its manufacture. And different disciplines of engineering, such as mechanical and industrial engineering.