Vertebrate Animals

Phylum: Chordata 4 basic characteristics distinguish chordates from other animals 1) presence of a notochord a) a flexible, rod-like structure which runs the length of the back side b) replaced by backbone in chordate adults 2) presence of dorsal nerve cord a) hollow tube above notochord b) becomes brain and spinal cord

3) presence of gill slits (at some point in development ) a) openings in the wall of the pharynx passage of water/oxygen 4) Presence of post-anal tail a)an muscular extension of the body that runs past the anal opening b) In some species, like humans, this feature is only present during the embryonic stage.

All chordate embryos have these characteristics All chordate embryos have these characteristics. Most will however lose or modify one or more of these structures as they mature into adults.

5 major classes of Chordates 1) fish 2) amphibians 3) reptiles 4) birds 5) mammals

Fish A) Agnatha: jawless fish 1) suction mouth to attach to prey, slit it open and feed on blood and tissues. 2) notochord remains a)lack bony skeleton  internal skeleton is made of cartilage 3) gills for gas exchange, not so much for feeding EXAMPLES: lamprey and hagfish(modern jawless fish that are parasitic) *

B) Chondrichthyes: cartilage fish 1) moveable jaw (can grasp, chew and crush). 2) skeleton made of cartilage rather then bone 3) scales (spiny and sandpaper like) 4) ex. sharks and rays

C) Osteichthyes : bony fish 1) skeleton made of bone (begin by forming a skeleton of cartilage) 2) presence of a swim bladder (allows gas to enter and leave the blood. Gas bag which control’s the fish’s depth. By changing volume in bag, they can control how deep they are.) EXAMPLES: tuna, trout, salmon, goldfish

General characteristics of fish 1) ectotherms (they can’t regulate body temperature) 2) gills used for respiration 3) body covered in scales 4) fins aid in movement 5) digestion, respiration, circulatory, excretory, nervous and reproductive systems

Amphibians A) evolution of the tetrapod 1) fins develop into limbs (need to be more muscular then fins to allow them to move on land, often have joints like elbows ) * https://www.youtube.com/watch?v=xkVgpYoiFmw

B) 3 classes 1) frogs 2) toads 3) salamanders

C) live a portion of life cycle in water 1) reproduction (external fertilisation) 2) metamorphosis Amphibians means “dual-life”. Hatch from eggs as fishlike larvae and at some point undergo metamorphosis, changing into and adult which can survive on land.

D) life on land Start out in water, has fins for moving and gills for gas exchange in water. After metamorphosis: 1) lungs for gas exchange with air 2) legs for movement on land 3) moist, smooth skin for gas exchange a) risk of drying out b) gravely affected by pollution 4) ectothermic: live in areas where temperature does not vary too much, other wise they have special adaptations to help them survive.

Reptiles A) 4 major groups 1) lizards 2) snakes 3) turtles 4) crocodilians

B) fully adapted to life on land 1) scales (prevent dehydration) 2) lungs for gas exchange 3) limbs point downward, with claws. Its body is higher off the ground which makes fast movement over land easier

4) ectothermic (basking in the sun to heat up and get energy 5) internal fertilisation (sperm fertilized eggs inside) 6) development of egg with a shell a) amniotic egg

Birds 1) 2 legs + 2 wings a) scales & claws on leg (usually four toes, webbed feet for swimming fish like ducks)

2) body covered in feathers a) made of keratin (like scales of reptiles) b) keratin forms a hollow tube (shaft) = light weight c) several functions warmth (down feathers, closest to body) coloration(identifies one bird from another and establishes territory and mates) flight*** (Quill featgers on wings and tail which help the bird to lift. Several adaptations) contour feathers to give them their shape. d) molting (loss of feathers which are replaced by new ones.

3) skeleton made of hollow bones p. 575-576

4) toothless beak a) several different shapes, nostrils (nares) b) Used for scratching, cleaning, repairing feathers, collecting materials, protection against other predators and to eat. c) Size and shape adapted to diet.

5) eyes on either side of head (never look at the same spot with both eyes a) some birds an exception (ex. owls) 6) more vertebrae on neck than other vertebrates a) it can turn head 180°

7) endothermic a) can regulate body temperature i) 45°C 8) internal fertilisation a) amniotic egg (bird lays egg about 2 days after fertilization.) b) mother/father cares for young

9) 4 chambered heart (important feature for animals which require a lot of oxygen)

Mammals A)characteristics 1)highly developed brain a) large cerebrum (allows mammals to perform complex tasks) b) convolutions ( capacity of the brain is increased because it is folded upon itself in ridges and grooves)

2) endothermic: regulate heat and temperature with sweat glands 3) breathe with lungs, aided by using diaphragm muscle 4) hair: regulate heat a) blubber/fat beneath the skin in aquatic mammals i) lost hair as a streamlining adaptation

5) 4 types of glands a) sweat glands (regulate body temp 5) 4 types of glands a) sweat glands (regulate body temp.) b) sebaceous glands (lubricate hair, skin) c) scent glands (communication) d) mammary glands (nourish young) 6) highly developed teeth a) diverse diets (herbivores, carnivores, omnivores)

7) internal fertilisation a) young develops in uterus i) mother/father cares for young *the more complex the mammal, the longer it associates with mother after birth.

8) 4 chambered heart B) 3 mammal groups 1) monotremes (ex 8) 4 chambered heart B) 3 mammal groups 1) monotremes (ex. duck-billed platypus, echidna) a) lay eggs b) milk from sweat glands

2) marsupials a) original development in uterus b) young are born very early in development and further development occurs in pouch c) milk from mammary glands *

3) placental mammals a) long gestation period i) remain in uterus until highly developed (time depends on size and type of mammal) ii) placenta nourishes young through umbilical cord b) young nourished with milk