اقرأ عن حيتان الـ Orcas الجميلة ذات الألوان الأبيض والأسود المميزة والتى يعدها العلماء مهددة، فى درس جديد باللغة الإنجليزية.
يقلق العلماء على هذا النوع من الحيتان بسبب البيئات التى يعيشون فيها، ويتغيرون إليها، وفى هذا الإطار نذكر لكم الكثير من التفاصيل عن هذه الحيتان الجميلة وعن تغذيتها وطريقة أكلها ونوعية الأسماك التى تأكلها وبيئاتها المختلفة، وكل ذلك من خلال القطعة الإنجليزية التالية، فلتقرأها بعناية…
Scientists are worried about orca whales in the waters of the northwest Pacific Ocean.
These huge black and white sea creatures spend summers near the San Juan Islands near the state of Washington. Six years ago, ninety-nine orcas swam there. Today, only seventy-eight orcas survive. During the past year alone, seven whales died.
This group of whales is called the southern population of orcas. Federal officials will decide next year if they should be officially listed as in danger of disappearing from Earth.
Orcas can grow longer than nine meters and weigh up to nine metric tons. They are sometimes called killer whales. However, they are not especially aggressive.
Millions of healthy orcas live in the world, many in cold waters. However, researchers say humans and a disappearing food supply are threatening the existence of the southern population of Orcas. Southern population orcas live in three groups, called pods. Each orca has its own markings. So scientists can identify each individual orca in the southern population.
Each May through October, visitors crowd into boats to follow the whales. The whale-watching industry is worth tens of millions of dollars a year. But scientists believe these whale-watching boats may be harming the orcas. The boats may be polluting the water. And the noise from the engines may be interfering with how orcas communicate with each other. Some experts say blocking the call of the whale interferes with its reproduction and eating.
Orcas mainly eat salmon. Some kinds of this fish are also in danger of dying out. So the whales eat fish that live near the bottom of the ocean. Such fish are more likely to contain industrial waste chemicals called P-C-B’s.
Scientists recently discovered that orcas store P-C-B’s in their fat. The experts say southern population orcas store more P-C-B’s than other kinds of orcas. Some researchers suspect the chemicals harm the whales. This has not been proven. Still, scientists know P-C-B’s can damage the nervous system and defense system against disease in humans.
Scientists are working hard to find ways to keep these huge sea animals from disappearing from Earth.