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What is a dolphin?

  • Dolphins belong to the group of animals that scientists call cetaceans. This means all the different types of whales and dolphins that there are in the world. This big group is split into two groups, baleen whales and toothed whales. Baleen whales sieve food through special filters called baleen plates. They don’t have any teeth at all. Dolphins are part of the toothed whale group. The two groups have special scientific names:
     
  • Mysticetes - baleen whales, e.g.. Blue Whale, Humpback Whale, Minke Whale.
     
  • Odontocetes - toothed whales, e.g.. Sperm Whale, Orca, Bottlenose Dolphin.    

This picture shows the different parts of a dolphin

 

 

This picture shows the different parts of a baleen whale

 

 

 ? ? How, Why, Where and What? ?

Where can I go to see dolphins around Britain?

  • There are Bottlenose Dolphins living in the Moray Firth, Scotland, and in Cardigan Bay. Wales. Often dolphins and porpoises can be seen around the Western Isles of Scotland such as Coll and Mull. Cornwall also seems popular and Funghie is a friendly wild dolphin in S. Ireland. But keep your eyes open! They can be found almost anywhere!
     

How long do dolphins live?

  • It depends on the sort of dolphin. Orcas can live over 50 years, female Orcas may live to be nearly 90. But in the same way that only a few people live to be 100, only a few Orcas will live to that age. Bottlenose Dolphins may live to be well over 30. In captivity, dolphins usually live much shorter lives.

What do dolphins eat?

  • Most dolphins eat fish. Some eat squid, molluscs or small crustaceans. Certain Orcas sometimes eat seals or even other dolphins.

How do dolphins keep warm?

  • Did you know that water carries heat away from your body more than 25 times faster than air? So to keep warm all dolphins have a thick layer of fat called blubber which can protect them even in icy seas. Dolphins living in colder water will usually have thicker blubber than those which live in warmer water.

What sort of animal are dolphins?

  • Dolphins are mammals. They have lungs and breathe air. They give birth to live young which are fed with their mothers’ rich milk. The mammal family also includes dogs, cats, elephants, sheep, apes, monkeys, humans and many others.

How can you tell a male and female dolphin apart?

  • Tricky! Sometimes size helps as male dolphins are usually larger than females of the same type. Otherwise you need to be very close because all the parts which show which sex an animal is are hidden inside the dolphin’s body. A male dolphin has one slit visible underneath about two thirds of the way along the body towards the tail. A female has a small slit each side of the main one. They hide the mammary glands where her baby will suckle.

How many different types of dolphin are there?

  • There are about 79 different kinds of whales, dolphins and porpoises. Some scientists say there are 45 kinds of dolphin. This includes the 26 types of ocean dolphin as well as river dolphins, porpoises, Pilot Whales, Orca, Beluga, Narwhal and others.

What is the difference between dolphins and porpoises?

  • The Dolphin and Porpoise families are part of the same big group of animals. They are very similar in many ways so it can be quite confusing. The differences are that most porpoises are quite small, the smallest is the Vaquita, only about 1.5m long. Porpoises don’t have a beak (some dolphins don’t have one either), and only one type of porpoise has a dorsal fin ( a few dolphins don’t have dorsal fins either - we said it was confusing!). But there is one difference that all porpoise share. It is the shape of their teeth. The teeth of a porpoise are flattened and shaped like spades. Dolphin teeth are usually cone shaped.

Where do dolphins live?

  • Dolphins are found all over the world. Some types live in only a small area. Other types can live in many different places. Bottlenose Dolphins seem to be found almost everywhere!

How fast can dolphins swim?

  • Dolphins swim by moving their tail up and down. A fish’s tail goes from side to side. Different types of dolphin swim at different speeds. Bottlenose Dolphins can travel at speeds of up to 27 km an hour, but just as we can’t run at full speed for long they would soon need to slow down. A more usual speed would be 5-10 kph.

How long can they hold their breath?

  • This varies with the type of dolphin. Bottlenose Dolphins can hold their breath for about 7 minutes, Belugas for about 12 minutes and Orcas for 20 minutes.

How deep can they dive?

  • Guess what’? It depends on the type of dolphin! Belugas and Bottlenose Dolphins have been known to dive to over 600m, Striped Dolphins to 200m. Most dives are shallower than this because their prey may not be down so deep.

What is echo location?

  • Echolocation is finding things by using echoes. Dolphins can make special clicking sounds. Scientists think the sounds can be aimed by the melon at the front of the head. The clicks bounce back off any object in their path. Dolphins can tell the size, shape and direction fish are travelling in. This is very important in dark, murky seas when dolphins cannot see their prey. It means they can catch fish in total darkness.

What are the dangers dolphins face?

  • It is a dangerous time to be a dolphin! Every year thousands and thousands of dolphins are trapped in huge driftnets. They get caught up in the very strong, almost invisible nets. Then they drown. Dolphins are also killed when they are hauled in in nets set around schools of tuna.
     
  • In some parts of the world dolphins are deliberately killed by fishermen because they eat the fish they want to catch. Luckily, in other places fishermen see dolphins as friends. There are even reports of dolphins and fishermen working together to catch fish!
     
  • In the Faroe Islands each year hundreds of Pilot Whales (a type of dolphin) are driven into very shallow water and killed horribly. Some of them are chopped up to be eaten and the rest are left to rot. Even pregnant females are killed. There is a big campaign to try to stop this dreadful slaughter happening. Some people are refusing to buy anything, especially fish, from the Faroe Islands until the killing is stopped.
     
  • Many scientists believe that pollution in the sea is harming dolphins. The sea is polluted in many different ways. Untreated sewage and poisonous chemicals as well as oil spills and dumped rubbish are all dangers to dolphins. When a dolphin eats a fish that is polluted the poisons may stay in the dolphin’ s body. Sometimes the poisons may pass from a mother’ s body to her calf The calf may then die.
     
  • Some dolphins are captured to be used in dolphin shows or scientific studies. They are stolen from their families. Often dolphins die when they are captured or soon after. The ones that live spend the rest of their lives as prisoners, often in very small pools. Many people enjoy dolphin shows but how many stop to think about how the dolphin is suffering?

Why are dolphins sometimes stranded on beaches?

  • Every year dolphins die when they get stuck on beaches. No one knows exactly why it happens. There may be many reasons. The dolphins might be old or ill. Some dolphins found on beaches died at sea and have been washed up by a high tide. The big puzzle is why dolphins which seem healthy become stranded. One idea is that they sometimes make mistakes trying to find their way using the Earth’s magnetic lines of force.

What should I do if I find a stranded dolphin on the beach?

  • If you ever find a stranded dolphin tell the Coastguard or Police straight away. If it is alive you will want to help but DON’T try to move it yourself. Dolphins are heavy! Never never try to drag a dolphin by the tail or flippers. You could do a lot of damage. Apart from getting help quickly you can do your bit by making sure the dolphin is kept cool and wet. Cover it in wet cloths soaked in sea water. Make sure the blowhole is not covered. Or pour water carefully over it making sure no water goes near the blowhole. Don’t let people bother the dolphin. Keep quiet and calm.
     
  • And remember, dolphins are very powerful. Don’t go too near to the tail. If the dolphin thrashes its tail you could be hurt.
     

Robin Petch and Kns Simpson, Dolphinicity Surveys/International Dolphin Watch, Parklands, N. Ferriby, E. Yorkshire. HU14 3ET. Tel (01482) 844468

 

 

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International Dolphin Watch 10 Melton Road, North Ferriby, E.Yorks HU14 3ET. England.
Tel: +44 (0)1482 632650 Fax: +44 (0)1482 634914 E-mail: idw@talk21.com