Download Fish- Introductions - holyoke

Ichthyes:
The Fish
What is a Fish?
-Aquatic vertebrate, usually with paired fins, scales and gills.
-fins for movement
-scales for protection
-gills for respiration
-Very diverse group composed of many classes of fish.
-
Evolution of Fish
-Fish were the first vertebrates
-Two important developments :
- jaws
- paired fins
The First Fish
-Strange, jawless animals with bone armour.
-Lived 500 million years ago and didn’t
change for 100 million years
The Age of Fish
-400 million years ago
-large adaptive radiation created new types of fish
-the new fish species spread around the world
-all were jawless
-both soft-skinned and armoured fish appeared
The Arrival
Of
Jaws
and Paired Fins
Jaws
-allowed fish to eat new types of
food
-gave them protection
Paired Fins
-paired pectoral and pelvic fins
-fins attached to girdles, b0ne
structures in the body
-fish could now swim quickly,
hunt and protect themselves
Modern
Fish
Agnatha: jawless fish
Chondrichthyes: cartilage
fish
Osteichthyes: Bony fish
Feeding
-every mode of feeding
-Some will eat anything, others
are very specialized
-Food:
-Enters mouth
-Into esophagus
-Stomach
-Broken down further in
the Pyloric Seca
Respiration
-Intestine
-Most fish move water over their
-Anus
gills and take out the oxygen
-Most fish have a single gill opening
protected by the operculum
-Lungfish have organs like lungs
and can breathe air
Circulation
-Closed circulatory system (blood is in vessels)
-A heart moves the blood in a loop around the
body: heart-gills-body-heart
-Complex, four-chambered heart
Excretion
-Waste is removed in the form of ammonia
-Kidneys help fish control the water in their bodies
Response
-Well-developed brain with different parts
-Most fish have good sense organs
-Lateral Line System lets fish feel movement in
the water
Movement:
-muscles bend their bodies in
a S-shaped movements
-fish move forward
-fins stabilize and steer
-body is streamlined
-many fish have a swim
bladder to help them float
Reproduction
-can be either internal or external
fertilization
-fish that hatch from eggs are oviparous
-Fish that are born alive are:
-Ovoviviparous (embryos
inside eggs)
-Viviparous (embryos
connected to the mother)