Dolphins. By lily pad

Transcription

1 Dolphins By lily pad

2 Table of Contents Dolphins, Dolphins Everywhere. 1 How long do they Live? 2 Born to Breed. 3 Home Sweet Home... 4 Funky Food.. 5 Dolphins in Danger 6 Splashing for some more?... Glossary.. 7 8

3 Hector s dolphin swimming underwater Dolphins, Dolphins Everywhere! There are more than 60 species belonging to the family delphinida, the largest family of cetaceans. Of those that are commonly referred to as dolphins, seven have been documented in the Philippines. These are the Spinner dolphin, spotted dolphin, Fraser s dolphin, Bottlenose dolphin, Rough-Tooth dolphin, striped dolphin, and Risso s dolphin. There are 33 types of marine dolphins, 4 kinds of river dolphins, and 6 kinds of porpoises which is 43 types of different dolphins. Some of their names are: bottlenose dolphin, pink river dolphin, orca (killer whale), Maui s dolphin ext. Some species of dolphins are going extinct. There are 7,000 individuals of hector s dolphin still alive today. There are fewer than 2,000 Ganges River dolphins. Around 1,000 Indus River dolphins still remain today. The vaquita is a porpoise not a dolphin but considered one of the most endangered cetaceans. Last but the most endangered, the Maui s dolphin. There are still 55 living today. Maui's dolphin jumping out of water A dolphin is actually a smaller version of a whale 1

4 How long do they live? Some dolphins have short lives while other species have plenty of time to enjoy their life. The killer whale can live up to years. The bottlenose dolphin can live over 40 years. The lifespan of a dolphin depends of what species it is. Life span diagram of dolphins The life span of dolphin varies from the killer whale to the Maui s dolphin. Most dolphins live up to 20 years old. However, it has been proved that some dolphins have reached the age of 48. The dolphin s death can sometimes occur slowly from time to time or even die before they reach half of their life. Dolphins can sometimes live less than usual. Death can happen when the dolphin has old age; diseases or parasites; bacterial, fungal, and viral infections; heart disease; respiratory disorders; skin diseases; stomach ulcers; tumors; or urogenital disorders. Dolphins playing and enjoying life Dolphins can shorten their lives. 2

5 Born to Breed Baby dolphins (called calves) have what it takes to survive. The calf will nurse from 11 months to 2 years. Calves have no air in its lungs so it sinks at first but its mom will quickly carry it to the surface. Another female dolphin called an aunt helps the mother and protects the baby. The Fetus being formed inside mother's stomach Baby dolphin with mom mother stays with its baby for more than 1 year until the calf will be between 3 to 8 years old. While the dad takes no part of caring the baby. It takes time before the baby dolphin will begin its life. It takes months before the baby will be born. The gestation is 9-17 months depending on the species. When it is time to give birth, the female will distance herself from the pod, often going near the surface of the water. It takes a process to develop a baby dolphin inside a mother s womb. Bottlenose dolphins breed all year round until they planed that they will have a baby. It takes 5-10 years for females but 10 years for males. Dolphins show that at nine weeks, the fetus starts moving in the womb. After a few days, the dolphin comes to life. Dolphins have whiskers when they are young. 3

6 Home Sweet Home Dolphins live in warm water regions. The Ganges or the Indus river dolphin is found in Bangladesh, India, Nepal, and Pakistan. Familiar dolphin species live in the saltwater seas and oceans. But there are also dolphins that live in freshwater rivers. The common dolphin is generally found Dolphin habitat map around the Mediterranean Sea but are also commonly seen in deep off-shore waters and to a lesser extent over continental shelves that are preferred to shallower waters. Some dolphin populations may be presented all year round, others appear to move in a migratory pattern. Dolphins proposing in their habitat Sometimes dolphin have some difficulty at home. Occasionally, most of the food they eat had might have died away when the dolphins were gone. Or their water is so polluted that had to find a different location. Even the water temperature can force the dolphins to say goodbye, and leave the place they once called home. The pink river dolphin lives in the Amazon River. 4

7 Funky Food A dolphin s stomach is compartmentalized for rapid food and digestion. Dolphins prefer a variety of prey such as fish, squid, and crustaceans. Adult bottlenose dolphins eat approximately 4% to 6% of their body weight in food per day. Different kinds of crustaceans Dolphins can see their prey, but in a murky condition because Dolphin catching fish they have poor eyesight. To make hunting easier, dolphins use echolocation. When dolphins makes sounds such as clicks, the sound bounces off objects or prey and it signals the dolphin where the object is. The foods that are available to dolphins vary with its geographic location. Coastal dolphins tend to eat fishes and bottom-dwelling invertebrates while offshore dolphins tend to eat fishes and squid. Some offshore dolphin were found with deep-sea fishes in their stomachs. This evidence suggests that offshore dolphins may have dive to more than 500m (1,600 ft.). Dolphins eat 30 pounds of food a day. 5

8 Dolphins in Danger Dolphins are disappearing fast. The most common danger to dolphins is accidently being caught in fishing nets. If they can t escape and come to the surface to breath, they ll drown. In the 1960s, yellow fin tuna were captured in vast purse-seine nets and a method known as dolphin fishing. This developed because Mass strandings people noticed that schools of yellow fin tuna followed some kinds of dolphins. The dolphins were easy to spot because they come to the surface to breath. The fishermen would spread their nets around the dolphins and sent speedboats or helicopters to herd the dolphins into the purse-seine nets, knowing that the tuna would go also. The dolphins got tangled and drowned. In 1972, laws were passed that tried to stop dolphin deaths through this method of fishing. Dolphins getting caught in a net While the dolphins image is generally positive, commercial fishermen sometimes consider them as competitors, saying dolphins eat their own weight of fish every day. Tuna fishermen, especially, have become notorious for their conflict with dolphins-in the past, they were deliberately drown about 300,000 dolphins a year in their nets, and stopped the practice only when confronted by a horrified and indignant public. When tuna is caught with no harm, it s called dolphin-friendly tuna 6

9 Interesting websites: Splashing for some more?

10 Glossary Cetaceans-a marine mammal of the order Cetacea; a whale, a dolphin, or porpoise. Crustaceans-any class of arthropods with a hard shell such as shrimp, crabs, and lobsters Endangered-(of a species) seriously at risk of extinction. Indignant-feeling or showing anger or annoyance at what is perceived as unfair treatment. Murky-very thick and dark; misty; hazy. Regions-an area or division, part of a country or the world having definable characteristics but not always fixed boundaries. Pod-a small herd or school of marine animals. Purse-Seine nets-a large seine, for use generally by two boats, that is drawn around a school of fish and then closed at the bottom by means of a line passing through rings attached along the lower edge of the net Womb- the uterus; a place of origination and development. 8