Ch. 39 - Fish

How many of you have a fish aquarium?What are some types of fish?What makes a fish different from other

animals that we have talked about?–Vertebrates

What phylum do vertebrates belong to?–Chordata

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Classification of VertebratesKingdom: Animalia

–Phylum: Chordata• Subphylum: vertebrata

All chordates at some stage develop 3 things.1. Notochord – dorsal rod of specialized cells.2. Dorsal nerve cord- hollow tube just above

the notochord.3. Pharyngeal pouches – small outpockets of

the anterior gut.Most have a post anal tail

3 Classes of fish

1. Agnatha – means “jawless”–Lampreys & hagfish–Both have a notochord their whole life.–Lamprey are mainly freshwater–Hagfish are marine–Hagfish have a toothed tongue that saws a hole in

its prey–Pg. 803

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Chondrichthyes (class) #2

Sharks, rays, & skatesMovable jaws; unlike agnathaPlacoid scales – tooth-like

spines on their skin.Pg. 817Video

Shark Characteristics

Very fast side-to-side swimming motionHave 6-20 rows of teeth pointing backwards.

Why?Can use more than 20,000 teeth in its lifetime.They have 2 pectoral fins just behind their

head that act like wings. They compensate for the thrust of the tail fin.

Video

Rays & Skates

Rays have more of a disk-shaped bodySkates have a triangular-shaped bodyBoth have flattened bodiesBoth have great camouflage and hide

well in the sand.Sting rays have a very powerful sting.Video

Osteichthyes (class) #33 types of bony fish

1. Lobe-finned fish –For over 70 million years scientists thought this

fish was extinct until 1938 a South American fisherman caught one.

2. Lungfish–Can live out of water for long periods of time.

3. Ray-finned fish–Have fins supported by bones(rays). Most fish

are this type. Examples?

External Anatomy of a Fish

Yellow Perch Perca flavescensOperculum – hard covering that protects the

gills on each side.Caudal fin – tail fin (thrust)2 Dorsal fins1 Anal fin2 Pectoral & Pelvic fins

–Helps steer, brake, & move up and down.

Integument – skin–Scales that overlap like shingles–Contain chromatophores, which are

cells that allow the fish to change colors.

Lateral line – senses vibrations (no ear)

Internal Anatomy of a Fish

Food Passage:Pharynx Esophagus Stomach

Pyloric ceca (intestine)The pyloric ceca are outpockets of the

stomach, that have lots of villi that line it.

Circulatory System

2-chambered heartAtrium – collecting chamberVentricle – pumping chamberThe blood is pumped through arteries to

small capillaries in the gills for has exchange. The blood then returns to the heart through veins.

Respiratory System

Gills with a large surface areaSwim bladder allows the fish to

adjust its density so it can float without using much energy.

Nervous System

5 lobes of the brain1. Optic lobes – the largest lobes, for

sight.2.Olfactory lobes – smell3. Cerebrum – intelligence4. Cerebellum – balance5. Medulla oblongata – regulates

interior organs.

Reproductive SystemSeparate sexes

1. External Fertilization – occurs when the eggs are fertilized outside the female’s body.–Ex. Salmon, trout, perch, (most species)

2. Internal Fertilization – occurs when the eggs are fertilized inside the body.–Ex. Guppies, swordtails, mollies

Spawning is the release of the eggs.Milting is the release of sperm.What is one way fishes protect each

other?–Schools of fish

What is the age limit on a fishing license?–16 -65