FISH(and chordates)

What is a chordate?

•Members of the ANIMAL KINGDOM and the PHYLUM CHORDATA

•They have a dorsal, hollow nerve cord and a notocord

Most chordates are vertebrates (SUBPHYLUM VERTEBRATA)

A few Chordates that are NOT vertebrates include a group know as protochordates. These include: Sea Squirts or Tunicates

and Lancelets

Protochordate Anatomy

What is a vertebrate?

---Animals with a backbone or vertebral column (endoskeleton)----Have spinal cord - dorsal, hollow nerve cord ----Front end of spinal cord develops a brain

Vertebrate Classes

• Jawless Fish (lamprey, hagfish)

• Cartilage Fish (sharks, rays…)

• Bony Fish (salmon, catfish,

goldfish…)

• Amphibians (frogs, salamanders…)

• Reptiles (lizards, turtles…)

• Birds (sparrows, hawks…)

• Mammals (humans, whales, cats..)

Fish Classification

•Kingdom- Animalia•Phylum- Chordata•Sub Phylum- Vertebrata•Classes- Agnatha, Chondrichthyes, Osteichthyes

General Fish Characteristics

•Gills•Backbone (vertebrae)•Paired Fins•Single Loop Circulation

Fish have a two chambered heart – and single loop circulation:blood is passed over the gills where it picks up oxygen, goes to the body and returns to the heart

Fish Respiration•Water flows over Gills

as fish opens mouth and swims.

•Water flows opposite direction of blood flow.

Fish Respiration•O2 diffuses from the water into the

blood.•Gills are made of thousands of gill

filaments.•Gills are covered by the Operculum.

The Nervous System

- Cerebrum - thinking, voluntary activities- Cerebellum - coordination- Medulla Oblongata - functions of internal organs- Lateral Line System - senses vibrations

Reproduction•Most fish lay eggs that are

fertilized externally - called spawning

•Some fish bear live young

Fish Adaptations• Lateral Line System- used to detect

vibrations, orient the fish in water, it is a line of cells running down the side of the fish.

• Operculum- gill cover, movement of operculum allows more water to be drawn in.

• Swim Bladder- a gas filled sac that helps the fish maintain buoyancy. Sharks don’t have a swim bladder!

• Fins- Dorsal, Caudal, Pectoral, Pelvic, Anal.

Class AgnathaJawless fish: Lampreys, Hagfish

Types of Agnathans•Hagfish- Ocean

scavengers, not much is known about them.

•Lamprey- fresh and salt water, they are parasitic and prey on other fish.

* Both have cartilagenous skeletons and sucker-like mouths.

Class Chondrichthyes

• Cartilage skeletons, no bones• No operculum, must keep

moving to breathe.• Have live births.• Special scales feel like

sandpaper.

Sharks and Rays

Types of Chondrichthyes• Sharks

• Sharks are adapted for a predatory lifestyle.

• Cartilage skeletons, no bones stiff pectoral fins (speed).

Types of Chondrichthyes

• Rays

Manta, and Sting Rays- live in shallow water, have mouths located on the underside, are fairly docile, wide flat bodies and wing-like fins that are flexible.

Class OsteichthyesBony Fish: Salmon, Carp, Tuna

Types of OsteichthyesRay Finned

– Most fish are this type– Fins are supported by bony

structures called Rays.

Types of OsteichthyesLobe Finned

– Fins are long, fleshy, muscular, supported by central core of bones.

– Thought to be ancestors of amphibians.

– Examples are: Coelacanth, Lungfish