Fishes, Amphibians, Reptiles
Section 1: What is a Vertebrate? Characteristics of CHORDATES Most are Vertebrates (have a spinal cord) Some point in life cycle all chordates have: Notochord Nerve cord that runs down their back (like a spinal cord) Slits in their throat area
NOTOCHORD Flexible rod that supports a chordate s back Lancelet has a notochord its whole life All vertebrates have part or all of notochord replaced with a backbone SLITS in Throat Area Also called Pharyngeal slits (or gill slits) Fish have them their whole life In humans, they disappear before birth
Characteristics of Vertebrates Most chordates Has backbone that is part of an internal skeleton Backbone = spine Formed by bones called vertebrae Joints in between each bone provide flexibility Hole through each vertebrae for spinal cord Makes up part of endoskeleton Protects internal organs Gives body its shape Does not need to be replaced Location for muscle attachment Allows greater growth
Keeping Conditions Stable Ectotherms Fish, reptiles, amphibians Animal whose body does not produce much internal heat Body temperature changes based on temperature of the surrounding environment Endotherms Birds and mammals Animals that regulate their own body temperature Adaptations including sweat glands, fur/feathers Larger variety of suitable living environments
Section 2: Fishes Aquatic vertebrate with fins Most are ectotherms Obtain oxygen through gills Have scales Largest group of vertebrates Three major groups: Jawless Cartilaginous Bony
Obtaining Oxygen Fish opens its mouth and take a gulp of water Water moves through throat and then to gills Gills contain many blood vessels Oxygen diffuses into blood vessels Carbon dioxide diffuses out Water flows out of slits beneath the gills
Circulatory System Oxygen-rich blood travels through closed system Two-chamber heart Pumps blood in one loop Heart gills rest of body back to heart
Reproduction External fertilization Eggs fertilized outside of female s body Male hovers close to female Male spreads a cloud of sperm cells over released eggs Young develops outside of female s body Internal fertilization- sharks, guppies Eggs fertilized inside of female Female gives birth to offspring
Jawless Fish No jaws and no scales Mouths designed for scraping, stabbing, and sucking their food Hagfishes- scavengers w/ large, slimy worm-like bodies Lampreys- Parasites of other fish
Cartilaginous Fish Skeletons made of cartilage Have jaws and scales Sharks, rays, skates Usually carnivores Rays and skates- hunt on ocean floor for mollusks, crustaceans, and small fish Sharks- attack and eat anything that smells like food Used jagged teeth arranged in rows Only front teeth are used for feeding Teeth move forward if front teeth are lost
Bony Fishes 95% of all fish Trout, tuna, goldfish Skelton made of hard bones Scales and a jaw Pocket on each side of the head that hold the gills Swim bladder Internal, gas-filled sac Helps stabilize fish at different depths
Section 3: Amphibians Means double life Beginning of life in water, adult life on land Return to water to reproduce Ectothermic vertebrate Two groups: Salamanders- keep tails in adulthood Frogs and toads- no tail in adulthood
Reproduction and Development FROGS -Eggs are fertilized externally and develop in water -Larvae wriggle out of jelly that coat the eggs -TADPOLES = frog larvae -Begin a free-swimming fish-like life SALAMANDERS -Eggs are fertilized internally -Larvae looks like adults -During metamorphosis, they lose their gills -Changes during metamorphosis are not as dramatic
Living on Land When amphibians become adults, multiple adaptations occur: Lose gills and develop lungs for gas exchange Circulatory system changes from single loop with a 2- chamber heart to two loops with a 3-chamber heart Atria- two upper chambers Left gets blood from lungs Right gets blood from body Ventricle- lower chamber pumps blood out to both lungs and body
More Adaptations Change from herbivores to carnivores Develop camouflage to help obtain food Develop skeletons and muscular limbs Powerful hind-leg muscles for jumping Skelton to absorb shock when landing Changes to the feet Webs to aid in swimming Sticky pads for climbing
Section 4: Reptiles Ectothermic vertebrates with lungs and scaly skins Snakes, lizards, turtles, alligators Can spend entire life on land Adaptations for water conservation: Dry, tough skin with scales Kidneys filter wastes which are excreting as urine Amniotic egg prevents embryo from drying out
Amniotic Egg Reptiles exhibit internal fertilization Lay eggs on land Egg contain shell and 4 internal membranes Shell has pores for gas exchange 4 Membranes for: Holding liquid that surrounds embryo Holding yolk (food for embryo) Holding embryo s wastes Exchange of O 2 and CO 2
Lizards Skin with overlapping scales Shed their skin and scales as they grow 4 legs with claws on toes Long tails, external ears, movable eyelids, two lungs Carnivores that jump at their prey Eat frogs, birds, insects depending on size
Snakes Identical skin qualities as lizards No legs, streamlined bodies, no external ears or eyelids Most have only one lung Eat small animals like mice Use long front teeth for hooking Some inject venom via their fangs Jawbones can spread apart Skull bones can move to swallow large prey
Alligators and Crocodiles Largest living reptiles Take care of their young Carnivores that hunt at night Hunting/Eating adaptations include: Strong, muscular tails fro swimming Jaws with large, sharp, pointed teeth Strong jaw muscles for biting down
Alligator and Crocodile Reproduction Care for eggs and newly hatched young Female stays near the nest Periodically, she will crawl over nest from the water to keep it moist Once eggs hatch, mother will scoop them up in her mouth and carry them away to a safe area in the water May stay with young up until a year or when they can feed and protect themselves
Turtles Reptile covered by protective shell w/ ribs and a backbone Shells are either hard or soft Some can bring head, legs, tail inside for protection Tortoises = land turtles Have sharp-edged beak instead of teeth for eating Can be carnivores or herbivores
Extinct Reptiles- Dinosaurs Ancestors of reptiles Extinct 65 million years ago Some may have been endothermic Herbivores walked on 4 legs Carnivores walked on 2 legs
Section 5: Vertebrates History in Rocks What are Fossils? Hardened remains of living things Bones, shells, skeletons Tissues are replaced by hard minerals Found in sedimentary rocks Layered rocks containing particles of: Clay Sand Mud Silt
More on Fossils Paleontologist = scientists who study extinct organisms by: Examining fossil structures Making comparisons to present-day organisms Can determine approximate age by: Studying sediment layers Examining radioactive decay
Vertebrate Evolution Fish- 530 million years ago Amphibians- 380 million Reptiles- 320 million Mammals- 220 million Birds- 150 million Birds and Mammals are both descendants of reptiles