Vertebrates I: Fish, Amphibians, and Reptiles

Vertebrates I: Fish, Amphibians, and Reptiles
Chapter 17

17A Body Systems in Vertebrate Animals
Introduction: Animals in the vertebrate group: Have vertebrae Skulls Skeletons that are alive (they are made if cells and require energy to grow) Endoskeleton – made of a combination of bone and cartilage Animals with endoskeletons have their primary support inside their bodies

Bone gives vertebrates a strong support system Cartilage is also strong, but more flexible than bone Example: the end of your nose is cartilage Bone and cartilage are living tissues that grow with the organism All skeletons have a vertebral column and skull Most vertebrates have ribs as well as other skeletal structures supporting their limbs (may be fins, arms, legs, or wings)

They also have joints between various bones and cartilage pieces that permit them to move Muscles pulling on the bones or cartilage cause the limbs to move at the joints Vertebrates testify to the greatness of God See Psalm 104:24-25

Vertebrates have more in common than just their skeletal similarities God designed them with organ systems that meet their needs for energy, response, movement, and nutrition 17A.1 Circulatory System Blood All vertebrates have blood (aka “the river of life”) Circulates throughout the body by the pumping of the heart

It brings food to cells that are far away from the digestive system Transports oxygen to and carries carbon dioxide from the cells that are distant from the lungs or gills Wastes, control chemicals, and many other necessary substances travel to and from the body’s cells in the blood See Figure 17A-1 Red – oxygenated blood – carries oxygen Blue – deoxygenated blood – had given oxygen away and now carries carbon dioxide The blood of all vertebrates is red. They only differ slightly in redness YOU DO NOT HAVE BLUE BLOOD!!

17A.1 Circulatory System Heart Chambers Vertebrate hearts contain spaces called chambers The walls of the chambers are made up of heart muscle The walls contract (squeeze), forcing the blood to move out. One-way valves prevent the blood from returning to the previous chamber Thus, a heart contracts over and over again, pumping blood in one direction ARTERIES - blood vessels that carry blood AWAY from the heart VEINS – blood vessels that carry blood TOWARD the heart

Different vertebrates have different numbers of chambers Fish – two chambers One receives blood, the other pumps it to the body The blood that leaves goes first to the gill to become oxygenated and then travels to the rest of the body Then eventually returns to the heart Most reptiles and adult amphibians – three chambered hearts One collects oxygenated blood from the lungs Another collects deoxygenated blood from the rest of the body Both of these empty into a third chamber where the two types of blood are mixed

Birds and Mammals – four chambered hearts Chambers on one side only pump oxygenated blood The other side pumps deoxygenated blood to the lungs, where it becomes oxygenated The oxygenated blood returns from the lungs to the other side of the heart The oxygenated side pumps the blood throughout the body In healthy animals with four chambered hearts, oxygenated and deoxygenated blood mix

17A.2 Respiratory System Gills Many vertebrates live their entire life underwater Gills take oxygen from the water and give off carbon dioxide Fish gills are shaped like tiny fingers and are richly supplied with capillaries Blood circulating near the surface of the gills make them appear red Capillaries – microscopic blood vessels in which blood often exchanges gases and other materials In gills, deoxygenated blood becomes oxygenated

17A.2 Respiratory System Lungs Vertebrates that have lungs are able to breathe air Lungs are air chambers inside the body where blood can obtain oxygen and give off carbon dioxide The lungs of reptiles, birds, and mammals are all different All lungs have many capillaries in which deoxygenated blood becomes oxygenated Breathing moves air into and out of the lungs

17A.2 Respiratory System Lungs There are several different methods that animals use to breathe Frog – fills its mouth with air and then forces the air into its lungs Birds – move air through their lungs by using muscles to control the size of connecting air sacs Mammals and humans – have diaphragms to help them breathe Diaphragm – a thin later of muscle that separates the chest chamber from the abdomen

17A.3 Nervous System Vertebrate nervous systems consist of two main divisions: the central ad peripheral nervous Central nervous system – made up of the brain, which is protected by the skull, spinal cord (which is protected by bones of the vertebral column), Peripheral nervous system – made up of nerves which branch off the central nervous system Sensory organs – sensory receptors scattered throughout the body; they are a major collection of sensory receptors and various supporting structures

17A.3 Nervous System Normally, a sensory organ only senses one environmental factor Cranial nerves – nerves that branch from the brain These connect the brain with sensory organs of the head Spinal nerves – nerves that branch from the spinal cord These transmit impulses from the spinal cord to various muscles and internal organs An organism’s reactions are controlled in the central nervous system The central nervous system also controls many internal processes

17A.4 Digestive System Food enters the body through the mouth and passes through short, tubular esophagus into the stomach Muscles in the stomach walls squeeze the stomach walls in and out to mix food with digestive enzymes When it is mixed, it moves into the small intestine In the small intestine has different enzymes to digest – here food is broken down into molecules small enough to be absorbed into the blood stream Two organs attached to the small intestine produce additional enzymes: Liver and pancreas

17A.4 Digestive System Liver – produces a greenish fluid called bile, which contains substances to help breakdown fats Bile released by the liver is stored in the gallbladder until it is needed Pancreas – smaller organ that makes and releases enzymes into the small intestine; these break down sugar, starches, proteins, and fats Small intestine wound in curves and loops in order to fit inside the animals body Large intestine – Food that cannot be digested passes through here; also where excess water is absorbed. Undigested food leaves the digestive tract through the anus

17A.5 Excretory System All vertebrates have kidneys to filter wastes from their blood Various waste products, including urea, are picked up by the blood as it passes through the body’s tissue Kidneys have tiny tubes surrounded by capillaries Wastes leave the blood and enter the tubes In each kidney, the wastes flow through these tubes into one large tube called the ureter Urinary bladder – where fluid is collected and stored before it passes out of the body Birds – wastes pass out of the body with indigestible materials Some amphibians, most reptiles, and all mammals and humans, wastes form urine

17B Fish Fish have fins, gills, and usually scales 17B.1 Fish Anatomy
They live in fresh or salt water Ectothermic Ectothermic – their body temperatures change with their surroundings A fish’s activity changes with the temperature 17B.1 Fish Anatomy A fish propels itself by flexing its entire body Paired fins control movements Streamlined body shape to move easily through the water Some have a swim bladder (helps them float at a constant depth) Swim bladder – an air filled organ that a fish uses to adjust to different water depths

17B Fish 17B.1 Fish Anatomy Fish have: closed circulatory system
two chambered heart and blood vessels Blood pumped from the heart to the gills, through the body, and back to the heart When blood passes through capillaries in the gills, oxygen diffuses into the blood stream Using Figure 17B-1 – Trace the flow of blood through a fish Scales – overlapping to give the fish some protection They grow larger as the fish grows Lateral line – located on each side of the fish; a string of sensory structures Can detect vibrations and pressure

17B Fish 17B.1 Fish Anatomy Nostrils of a fish are NOT used for breathing; used for smelling Most fish reproduce by spawning During spawning – female fish release millions of eggs which are then fertilized by the male However, only a few survive to become adult fish Most fall prey to predators A few fish, guppies, reproduce by giving birth to live fish rather than spawning

17B Fish 17B.2 Fish Groups Jawless Fish Cartilage Fish Have no jaws
No scales or paired fins Worm-like creatures with skeletons composed of cartilage Examples: lampreys and hagfish Some species of lamprey are parasites, feeding on the body fluids of other fish Hagfish are scavengers Cartilage Fish Have endoskeletons made of cartilage Have jaws, scales, and paired fins Examples: Sharks, skates, and rays Sharks have to keep water moving over their gills to ensure oxygen supply They swim with their mouths open They lack a swim bladder; instead they have a large oily, liver that is less dense than water Skates and rays rest on the ocean floor

17B Fish 17B.2 Fish Groups Bony Fish The largest group of fish
Includes: catfish, bass, flounder, goldfish, guppies, and trout Endoskeleton made of bone Have jaws, paired fins Most have scales Some grow no longer than the width of a pencil; others can reach 4.3 meters Some live in salt water; others in fresh Some warm water of the tropics; some frigid polar temps

17C Amphibians Amphibians are ectothermic
Live in water when young, but can live on land as adults The name comes from the greek word that means, “double life” The name reflects two ways of living: in water and on land

17C Amphibians 17C.1 Amphibian Development
Metamorphosis – the process that changes an amphibian from a gilled, aquatic organism to an air-breathing organism Young amphibians possess gills, but adults usually have lungs Gills and lungs are not the only organs used for respiration Most have thin, moist skin They can exchange gases through their skin (carbon dioxide and oxygen) because they have tiny blood vessels close to the surface Other changes metamorphosis includes: Two chambered heart to three chambered Growth of two pairs of limbs Gradual loss of a tail

17C Amphibians 17C.1 Amphibian Development 17C.2 Amphibian Groups
Though many adults live on land, they still live near water, for all must return to water or moist places to lay their eggs 17C.2 Amphibian Groups There are two major groups of amphibians – with a tail and without Tailless Amphibians Frogs and toads Frogs have smooth, moist skin and are usually near water Toads have rough, dry, bumpy skin and can be found far from water Most lay jelly-coated eggs in water, where they are fertilized externally They hatch to become tadpoles Tadpoles have gills and tails, but during metamorphosis, they develop lungs and their tail gradually dissolves

17C Amphibians 17C.2 Amphibian Groups Frogs and toads are ectothermic
Temperature of their surroundings affect their activity They are less active in the cool (autumn and winter) Frogs usually bury themselves in the mud at the bottom of a lake of stream during the winter Toads burrow in soft, moist soil Hibernation – the winter state of inactivity During hibernation, the animal’s life processes slow down and energy supplies stored during the summer months are used up A similar period of activity called ESTIVATION sometimes occurs during hot, dry weather

17C Amphibians 17C.2 Amphibian Groups
Frogs eat insects, worms, slugs, snails, and other small animals It will attack anything that moves and is small enough to fit into its mouth A large North American bullfrog will eat young water birds, ducklings, young turtles, and even small fish Some will even eat other small frogs! A frog catches its food with its tongue Its tongue is short, thick, and attached to the front of the mouth When it sees food, it flicks its tongue out and stretches it out The tip of it is sticky When it touches food, the frog flips its tongue Frogs have two sets of teeth They do not use them for chewing, rather for keeping prey from escaping

17C Amphibians 17C.2 Amphibian Groups
One set of teeth forms a ridge of tiny maxillary teeth around the rim of the upper jaw The other set, the vomerine teeth, is located in two spots at the front of the roof of the mouth The frog swallows by blinking and bulging its eyes When the frog closes its eyes, they push down into the frog’s mouth, forcing the food back into the esophagus

17C Amphibians 17C.2 Amphibian Groups Tailed Amphibians Salamanders
They have tails into adulthood The young usually have gills and develop lungs later They also have thin, moist skin to help with gas exchange The Appalachian region of the US has more salamander species than any other region on earth Most are small and less than 15 cm (6 in) long One Japanese salamander species can grow to be 1.5 m (5 ft) long!

17D Reptiles All reptiles breathe air and do not experience the life- changing metamorphosis 17D.1 Reptile Characteristics Ectothermic Dry, scaly skin Lay eggs with leathery shells Most have a three-chambered heart – but one chamber is partially divided The have lungs their entire lives Can be found in both wet and dry environments The scaly skin protects it from drying out The leathery eggs allow eggs to be laid on land far from water They fertilize eggs internally, within the female’s body

17D Reptiles 17D.2 Reptile Groups The most famous – extinct dinosaurs
Living reptiles can be divided into four groups: Snakes and lizards Alligators and crocodiles Turtles Tuataras

17D Reptiles 17D.2 Reptile Groups Snakes and Lizards
Snakes have no legs, ear openings, and immovable eyelids Most lizards have four legs, ear openings, and moveable eyelids Both shed their skin periodically in a process called molting Snakes do not hear. They also have poor vision Their immoveable eyelids are actually clear scales that are shed each time it molts

17D Reptiles 17D.2 Reptile Groups
What snakes lack in sight they make up in other sense organs Snakes have a keen sensitivity to molecules When a snake flicks its tongue, it is sensing the air – helps it to detect food or danger Some snakes can detect body heat of its prey Pit vipers – such as rattlesnakes – have small pits on their heads that contain organs that can detect heat Snakes are meat-eaters Benefit to humans – Eat insect pests, rats, and mice

17D Reptiles 17D.2 Reptile Groups Most snakes are nonpoisonous
Poisonous ones inject poison through hollowed fangs or grooved teeth Nonpoisonous coil around prey and squeeze! They are capable of swallowing prey much larger in diameter They swallow food whole – they cannot chew! They have double hinged jaws Its throat is elastic

17D Reptiles 17D.2 Reptile Groups
Snakes are found in almost every environment Most lizards are found in hot or warm environments; dry Lizards can grow quite large – komodo dragon – up to 10 ft! Some lizards can change skin color!

17D Reptiles 17D.2 Reptile Groups Crocodiles and Alligators
Can be found in and near shallow waters of warm streams, rivers, swamps, and lakes Usually found in tropical and subtropical environments Few crocodiles venture into salty water Use their large tails to propel themselves through the water Raised eyes and nostrils allow them to keep them above water while the rest of the body is submerged Diet includes: fish, turtles, various large and small mammals (usually attacked while drinking), others of their own kind and occasionally humans Alligators and crocodiles can be distinguished by their snouts – Alligators – broad, rounded snouts Crocodiles – narrow, pointed snouts

17D Reptiles 17D.2 Reptile Groups Crocodiles and Alligators Turtles
The alligator is found all over the southeast Crocodiles are restricted to southern Florida Turtles Sea turtles – live in the ocean Tortoises – live on land Terrapins – freshwater turtles that may venture onto land Sea turtles have paddle-shaped legs used in swimming Other turtles have clawed legs They have two hard, bony shells to cover their bodies The shell is composed of bony plates covered with large scales It serves as a good defense Some have a hinged lower shell to close tightly for protection

Vertebrates I: Fish, Amphibians, and Reptiles

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Vertebrates I: Fish, Amphibians, and Reptiles

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