Fish, Amphibians, Reptiles and Birds (Chapter 28-29)
Characteristics of Vertebrates
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Have a backbone
Specialized cells that develop into a nerve cord
o Neural crest forms – a group of cells that develop form the nerve cord, which
portion of the brain, skull and sense organs develop
Vertebral Column
o Spinal cord
o Surrounds and protects the dorsal nerve cord
o Replaces the notochord with cartilage (tough flexible material) or bone
o Strong flexible rod for muscles to attach to
o Allows for increase in speed and strength
Closed circulatory system
Characteristics of Fish
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Most have a vertebral column
Jaws
o Allows to prey on larger animals
o Defense against predators
Paired fins,
o Used for balance and steering and propulsion
Scales
o Ctenoid scales and Cycloid scales are made of bone and skin and are thin and
flexible
o Placoid scales are made of toothlike materials and are rough and heavy
o Ganoid scales are diamond shaped and made of both enamel and bone
Gills
o Covered with lamellae- folded structures of the gills containing many vessels to
diffuse oxygen and carbon dioxide from the blood
o About 85% of oxyen is removed
o Operculum is a movable flap that covers the gills protecting them and it also aids in
pumping water
Single looped circulatory system
o Heart pumps blood in vessels
o Blood passes heart one direction then to gills, then through the body delivering
oxygenated blood
o Hearts have two main chambers
 Atrium which receives blood from the body
 Ventricle which pumps blood from the heart to the gills
Feeding and digestion
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Fish swallow food passes through the esophagus to the stomach where digestion
begins
o Pyloric ceca a small pouch at the junction of the stomach and the intestine that
secretes enzymes for digestion and absorption into the blood stream
Excretion
o Cellular wastes are filtered by kidneys
o The main functional unit of the kidney is the nephron, which is a filtering unit that
helps maintain the salt and water balance of the body
o Some cellular wastes excreted by the gills
Brain and senses
o Nervous system consists of a brain and spinal cord
o Cerebellum is involved in coordinating movement and controlling balance
o Receptors that sense smell and detect chemicals in the environment
o Olfactory bulbs record and respond to incoming chemical input
o Color vision, optic lobes responsible for visual input
o Cerebrum coordinates input from other parts of the brain
o Medulla oblongata controls the internal organs
o Lateral line system are special receptors that enable fish to detect movement and it
keeps them upright and balanced
Reproduction
o External fertilization
o Spawning in when females and males release gametes near each other in the water
o Sharks reproduce internally
Movement
o Streamlined bodies
o Mucus that lubricates surface to reduce friction
o Swim bladder is a gas-filled space that allows fish to control their depth
Classes of Fish
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Jawless fish
o Class Myxini is the hagfish
 No scales, eel like shape, no fins, no bony skeleton
 Have a notocord
 Live on sea floor and feed on dead fish or invertebrate
 Produce slime to prevent from being caught by predators
o Class Cephalaspidomorphi
 Lampreys
 No scales, eel like shape, no fins, no bony skeleton
 Have a notochord
 parasitic
Cartilaginous fish
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Body made of cartilage
Class Chonodrichthyes
 Sharks, skates, rays
 Several rows of teeth
 Streamlined bodies
 Sense chemicals in water
 Lateral lines
 Whale sharks are filter feeders
Bony fish
o Class Osteichthyes
 Rayed fish : most fish today
 Lobed fish have muscular joints like land vertebrate
 Use lungs to exchange air like the lung fish
Amphibians
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Characteristics
o Frogs, newts, salamanders, toads, legless caecilians
o Four legs
o Moist skin with no scales
o Gas exchange through skin
o Lungs
o Double loop circulatory system
o Aquatic larvae
Feeding/digestion
o Frog larvae are herbivores
o Salamander larvae are carnivores
o Adults in both are carnivores feeding on invertebrates and small vertibrates
o Jaws or tongues used to catch prey
o Mouth---esophagus----stomach----small intestine----large intestine
o Cloaca is a chamber that receives the digestive wastes, urinary wastes, and egg or
sperm before they leave the body
Excretion
o Filter wastes through kidneys
o Excrete ammonia or urea as wastes products of cellular metabolism
o Ammonia is the end product of protein metabolism excreted by those that live in
water
o Urea is made from ammonia in the liver and stored in the bladder for those on land
Respiration
o Through skin and gills
Circulation
o Double looped
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First loop moved oxygen poor blood from the heart to pick up oxygen in
thelungs then back to the heart
 Second loop moves oxygen filled blood from the heart to the body where
diffused out
 Have a three chambered heart
 Two atria
o Right atrium receives deoxygenated blood from body
o Left atrium receives oxygenated blood from lungs
 ventricle
Brain and senses
o Nictitating membrane is a transparent eyelid that can move across the eye to
protect it underwater and keep it from drying out on land
o Tympanic membrane is an external eardrum to hear high pitched sounds and to
amplify sounds from their vocal cords
o Ectotherms they obtain their body temperature from the external environment
Reproduction
o Lay eggs in water to be fertilized by males
Orders of Amphibians
o Order Anura these are the toads and frogs
 Lack tails
 Frogs have longer and more powerful hind legs than toad
 Frogs moist smooth skin toads dry and bumpy
o Order Caudata these are the salamanders and newts
 Long slim line bodies
 Have tails
 Moist and smooth
o Order Gymnophiona these are the caecilians
 No legs
 Wormlike
 Internal fertilization
 Feed on worms and other invertebrates