FISH! Basic Characteristics 5 th Grade

Fish: a vertebrate that lives its entire life in water  All fish have several similar characteristics:  Fish are cold-blooded vertebrates that live in fresh or salt water (ectotherms)  Fish have backbones  Fish have gills that take oxygen out of the water and get rid of carbon dioxide

Fish: a vertebrate that lives its entire life in water  Most but NOT all fish also :  Have scales  Use fins to move

Did you know?  Nearly half of all vertebrate species are fishes  Fishes have lived on Earth longer than any other kind of vertebrate!

When do we use the plural “fish” and when do we use the plural “fishes?”

Use plural “fish” when you are talking about more than one of the same species of fish

Use plural “fishes” when you are talking about more than one species of fish

Do fishes need oxygen?

Yes: Fishes need Oxygen!  All fishes get their oxygen from water!  As a fish swims, it opens its mouth, takes a gulp of water (which has oxygen in it)  When the fish opens its mouth to take a gulp of water, it absorbs the oxygen through blood vessels and pushes out the water and carbon dioxide through its gills

How do gills work?  The fish opens its mouth to allow water in  The gills have tiny blood vessels that can absorb oxygen and filter out everything else!

Gills:  Look like tiny feathers  Have blood vessels in them  As water flows over the gills, oxygen moves from the water into a fish’s blood

If oxygen is moving into the blood, what is moving out of the blood and into the water?

Carbon Dioxide!  Carbon Dioxide is a fish’s waste product that flows out of the fish through slits beneath the gills

Movement: How do fishes move?

Movement:  Most (not all) use fins:  HOW do fins help fishes swim?

Fins:  Each fin has a thin membrane stretched across bony supports  A fin provides a large surface to push against the water  this helps the fish move more quickly through the water  Similar to a scuba-diving flipper

Fins:

Each fin has a thin membrane that stretches across bony supports. Like a canoe paddle, a fin provides a large surface to push against the water.

Reproduction:  Most fishes have external fertilization (the eggs are fertilized outside of the body)  Some fishes (like sharks and guppies) have internal fertilization, which means that the eggs are fertilized inside the female’s body. The young develop inside the mother’s body until they are mature enough to live on their own

Nervous System: most fishes can see in the water much better than humans, and have a very good sense of smell, touch, and taste

What does a nervous system help fishes do?

2 ways a nervous system helps a fish:  1) helps a fish find food  2) helps a fish avoid predators

Example: Catfish whiskers –what do these do?

The whiskers of a catfish have many taste buds. To find food, the catfish drags its whiskers along the muddy lake or river bottom