Ch. 41 - 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

Classification of Vertebrates Kingdom: 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. 815

Chondrichthyes (class) #2 Sharks, rays, & skates Movable jaws; unlike agnatha Placoid scales – tooth-like spines on their skin. Pg. 817

Shark Characteristics Very fast side-to-side swimming motion Have 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.

Rays & Skates Rays have more of a disk-shaped body Skates have a triangular-shaped body Both have flattened bodies Both have great camouflage and hide well in the sand. Sting rays have a very powerful sting.

Osteichthyes (class) #3 3 types of bony fish (pg. 822) 1. Lobe-finned fish (PG. 821) 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. (pg.821) 3. Ray-finned fish Have fins supported by bones(rays). Most fish are this type. Examples?

External Anatomy of a Fish Yellow Perch  Perca flavescens Operculum – hard covering that protects the gills on each side. Caudal fin – tail fin (thrust) 2 Dorsal fins 1 Anal fin 2 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 heart Atrium – collecting chamber Ventricle – pumping chamber The 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 area Swim bladder allows the fish to adjust its density so it can float without using much energy.

1. Optic lobes – the largest lobes, for sight. Nervous System 5 lobes of the brain 1. Optic lobes – the largest lobes, for sight. 2.Olfactory lobes – smell 3. Cerebrum – intelligence 4. Cerebellum – balance 5. Medulla oblongata – regulates interior organs.

Reproductive System Separate 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