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12-1
Phylum Chordata – vertebrates
Characteristics
• notochord: flexible rod supporting back; part/all replaced by
backbone
• nerve cord: spinal cord connecting brain to nerves
• pharyngeal slits: in the throat area; disappear before birth in some
Endoskeleton
• grows with animal
• includes backbone (vertebral column, spinal column, spine), skull,
ribs, arm/leg bones
backbone is made of vertebrae lined up in a row; can be made of bone
or soft, flexible connective tissue called cartilage
• functions – supports body, protects body, gives shape to body, gives
muscles place to attach
Body Temperature
• ectotherm or cold-blooded animals such as fish, amphibians, and
reptiles do not produce internal heat inside their bodies; body
temperature changes with that of the environment
• endotherm or warm-blooded animals such as birds and mammals
produce internal heat inside their bodies; can control/regulate their
body temperatures; fur/feather/hair, sweat glands are adaptations to
maintain their body temperature; can live in a greater variety of
environments
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Fish
General
• First vertebrates; largest group of vertebrates
• Live in water
• Move by fins that provide a large surface area to push against water
• Gills to get oxygen from water; gills are red since they are surrounded
by blood vessels
• Scales with overlapping plates made of a hard substance
• Ectotherms
• Closed circulatory system; one-loop circulation (heart-gills-rest of
body-heart)
• Carnivores or filter feeders
• Highly-developed nervous system to find food and avoid predators
• External fertilization mostly; sharks have internal
Types: based on mouth structure and skeleton
1. Jawless (hagfish, lamprey)
- earliest
- no scales
- no jaw; can’t bite; have structures to scrape, suck, stab
- cartilaginous skeleton
2. Cartilaginous (ray, shark, skate)
- pointed scales
- jaws; are carnivores or filter feeders
- skeleton made of cartilage
- shark
• streamlined body (fast)
• jagged teeth that can be replaced
• depend on currents to pump water over gills
• strong smell not eyesight
3. Bony (trout, tuna, goldfish)
- jaws
- skeleton made of bone
- have swim bladder filled with gas to help stabilize at different levels
in water (large volume of gas means greater buoyancy means it rises)
- live in salt and fresh water
Food for People
• populations reduced by overfishing
• some raised on “farms” – aquaculture
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Amphibians
General
• “double life” (live in water as young and on land as adult)
• ectotherms
• reproduction
- lay eggs in water
- external fertilization (frog, toad); internal fertilization (salamander)
- eggs hatch into larvae that swim and have gills to get oxygen; undergo
metamorphosis into adults with lungs and moist skin to get oxygen
(salamander larvae resemble adults)
- eggs coated with clear jelly to keep moisture in and prevent infection
- parents don’t take care of eggs after fertilization in most
• circulatory system
- closed
- one-lop for young; two-loops for adult (heart-lung/skin-heart and
heart-body-heart)
- heart has 3chambers with 2 upper receiving ones called atria/auricles
and 1 lower pumping one called ventricle
• adaptations for living on land
- strong skeleton
- muscular limb
- eyes with transparent membrane to keep from drying out; have eyelids
Types
1. Frogs/Toads
- hop/leap with powerful hind leg muscles and a skeleton that can
absorb the shock of landing
- frog: skin is smooth and moist
toad: skin is bumpy and dry; have lumps behind eye with poison
- camouflage helpful against predators as well as for finding prey
- tadpoles are herbivores; adults are predators feeding on insects/small
animals
2. Salamanders
- tail
- stalk/ambush their prey; can’t jump
- no lungs; use moist skin to get oxygen
Amphibians in Danger
• Reasons
- habitat destruction
- sensitive to changes in environment such as insecticides and other
chemicals because eggs lack shells and skin is very thin
• Other animals become endangered too as a result (food chain is
affected)
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Reptiles
General
• ectotherm
• live on land and have lungs
• heart has 3 chambers; 2-loop and closed circulatory system
• lay eggs; internal fertilization
• scaly skin
Water Conservation
- egg: has soft, leathery shell and membranes to protect the embryo and
keep it from drying out
- skin: is dry, tough, scaly to protect and keep water in
- kidneys: concentrate urine
Types
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Snakes/Lizards
skin with overlapping scales; shed as grow
live in warm places
snakes
no legs, eyelids, external ear
1 lung
move by alternating contraction of muscles on ribs and backbone in
side-to-side manner
• are carnivores, can eat large prey (jawbone spreads); some have
curved teeth; others have fangs
- lizards have tails
2. Turtles
- have shells (some soft); have scales on shell plates
- have sharp beaks instead of teeth; some carnivores, others herbivores
3.
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Alligators/Crocodiles
largest living reptiles
carnivores, nocturnal, rest in sun/water during day
have strong tail
have pointed teeth
have strong jaw muscles
they care for eggs and newly hatched young
alligators
large bulging eyes
broad, round snout with few teeth visible when mouth is shut
crocodile
pointed snout with many teeth visible when mouth is shut
4. Dinosaurs
- extinct reptiles
- were dominant during Mesozoic Era