Monday, April 8, 2013

Discover an Underwater Ecosystem

By Alex Asher


Most fish have a special part inside their bodies called a swim bladder. Air inside the swim bladder helps the fish float through the water. The fish can adjust how much air is in its swim bladder. If it wants to swim deeper, it lets some air out and if it wants to swim up towards the surface, it will let more air into its swim bladder.

Some animals that have the word "fish" in their names are not really fish. Some examples are cuttlefish (they are mollusks, see below), jellyfish (they are actually plankton), and starfish (they belong to a group called "echinoderms"). Can you think of any other animals that are called fish but do not have the things it takes to be a real fish?

Whales, dolphins, porpoises, walruses, manatees, dugongs, seals, and sea otters are all mammals that live in the ocean. Some, like seals and sea otters, can also live on land, but they spend most of their time underwater. These animals have lungs, are warm-blooded, give birth to live babies (they don't lay eggs) and nurse their babies, but they live in salt water instead of on dry land like most mammals. Since they have lungs, they need to breathe air instead of just getting oxygen from the water like fish and other ocean animals can. Instead of breathing air through their mouth or nose like we do though, a whale or dolphin uses a special hole on the back of its head called a blow hole to get air from above the surface of the water. Then it dives back down into the water and swims around for a few minutes before it needs to come up to breathe again. When it does, it breathes out the air through the blow hole and then breathes in more air so it can go back under the water again. When the air goes out of the blow hole, there is usually some water that squirts out with it, making a little spray at the surface (like the killer whale in the picture). Marine mammals also have some fur or hair, but sometimes it falls out by they time they become adults.

Most kinds of whales live in groups called pods. The pods are kind of like families. The older whales take care of the younger whales, which are called calves. Whales stay together in their pods for most of their life. Most kinds of whales live somewhere in the middle of the ocean so that they can quickly get to the surface since they need to go up for air a lot.

The aquatic displays and hands-on touch tanks at aquariums introduce children and parents to our local marine flora and fauna. Outreach programs are developed and presented by our marine staff and focus on place-based experiences and a hands-on approach to learning.




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