Day 17 Fish and Amphibians

Chordata (45,000 Species)

Chordate characteristics

-Bilaterally symmetrical

-Deuterostomates

-At one point in their lives they have each of these 4 things

-Notochord

-Pharyngeal slits

-Dorsal tubular nerve cord

-Postanal tail

-Presence of endostyle or thyroid gland

-Complete digestive tract

-Ventral, contractile blood vessel (heart)

Fish

Fish is an informal name for three classes of vertebrates

The three classes of fish are

Agnatha (Jawless Fish)

Chondrichthyes (Cartilaginous Fish)

Osteichthyes (Bony Fish)

Class Agnatha

-Have no Jaw

-The Jawless fish are of the most primitive fish living today

-Because they have no jaw they feed by suction

-They have a round mouth with rows of teeth

Lampreys

-Mostly a freshwater fish. Breed in lakes and rivers and sometimes move to the sea as adults

-Attach to other animals and suck their blood

UNSPECIFIED - AUGUST 01: A pair of sea lampreys cling to and feed on a brown trout, Great Lakes, North America (Photo by James L. Amos/National Geographic/Getty Images)

Class Chondrichthyes

-Cartilaginous fishes

-Includes the sharks, rays, skates, and ratfishes

-Have a cartilage skeleton

-Placoid scales- rough sand paper like skin because placoid scales are similar to teeth.

-Point backwards

-Paired lateral fins

Order of Sharks

-Caudal fin- pointing up and down

-Heterocercal- Upper lobe is longer than the lower lobe

-Two dorsal fins

-Paired pectoral fins

-Five to seven gill slits

-Replaces teeth that are lost

-Can sense electricity

-Can sense vibrations in the water

The worlds largest fish is a whale shark

A whale shark can grow up to 50ft. It has no teeth and eats plankton

-Sharks are not very dangerous to humans

-Only about 5 deaths world wide happen because of sharks

-Almost 500,000 people in the United States a year go to the emergency room because of dog bites

The shark that is the most dangerous to humans is the great white shark and the bull shark has the most dangerous human shark attacks

Order Batoidea (Rays and Skates)

-Rays and skates are dorsally and ventrally flattened

-Rays have live birth

-Skates lay eggs

-Skates have more of a triangle shaped front end

Bat Rays

Class Osteichthyes

The Bony Fish

-23,000 species

-96% of all fish and about half of all vertebrates

Characteristics of Osteichthyes

-Cycloid scales- smooth, made of bone but have skin over them

-Ctenoid scales- have tiny spins on their exposed boarder

-Operculum or Gill Cover- a flap of bony plates that protects the gills

-Usually homocercal- The lobes of the tail fin are the same size

-Fin rays- spins that support the fin

-Terminal mouth- Mouth at the end of the body unlike the ventral mouth of the chondrichthyes

-Swim Bladder- Gas filled sac just above the stomach to adjust buoyancy

-Needed since bones are heavier than cartilage

Mud Skipper

SciShow: Salamander Fish

Watch this video on Salamanderfish. Create a box in your sketchbook, title it "Salamanderfish" and take notes, write down interesting things that you learn from the video and include an image in your sketchbook.

SciShow: Fish with Hands

Watch this important video up until 3:18. You do not have to watch the second half of the video unless you want to.

PBS: When Fish Breath Air

This is a very interesting but optional video.

Class Amphibians

(Two lives)

-Amphibians were the first fully terrestrial vertebrates

-Amphibians have two lives

-They are born underwater and have gills

-Then as they grow they go through a metamorphosis growing lungs and become terrestrial

-Have aquatic eggs that must be laid underwater

-Most need to stay moist to help them breath through their skin

Class Amphibia: Frog vs Toad

Watch this video on the class Amphibia. Create a box in your sketchbook, title it "The Class Amphibia" and take notes, write down interesting things that you learn from the video and include an image in your sketchbook. Make sure you understand the characteristics of amphibians and can tell the differences between their orders.