non-vertebrate chordates, fishes, and amphibians chapter 30
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Non-vertebrate Chordates, Fishes, and AmphibiansChapter 30
Phylum Chordata
Contains three sub-phyla:– Vertebrata– Urochordata– Cephalochordata
All chordates at some point in their life span must possess four characteristics:
1) A hollow, dorsal nerve cord
2) A notochord (supporting rod)
3) Pharyngeal gill slits
4) A tail that extends beyond the anus
Also known as the tunicates or “sea squirts”
Basically a sack with two siphons.
Examples: amphioxus and lancelets
Vertebrates
Most numerous chordates Anterior, large brain Jointed internal skeleton Usually two pairs of appendages and
some type of tail Closed circulatory system Gills or lungs and a chambered heart
7 major classes of vertebrates
Jawless fishes, cartilaginous fishes, bony fishes, amphibians, reptiles, birds, mammals
Ectotherms = “cold-blooded” body temp changes with the environment.
Endotherms = “warm blooded” body tem remains fairly constant
FISH or FISHES
Both words can be used for the plural of a fish.
“Fishes” is often used when talking about taxonomy or classification.
1. Class Agnatha “jawless fishes” Most primitive vertebrates No scales nor fins Cartilage skeleton No jaws Both fresh and salt water varieties. examples: lampreys and hagfish
LAMPREY
Both fresh and salt water. (parasitic)
Possess a tongue with teeth that gnaw a hole in its victim then sucks out the blood.
Can be harmful to fish populations.
HAGFISH
Only found in salt water. scavengers
Also known as “slime eels”
Produce great amounts of slime for defense. Can tie themselves in a knot
2. Class Chondricthyes
Chondros (Gr. Cartilage) Ichthys (Gr. Fish) Mostly marine 2 chambered heart Movable upper and lower jaws ex. Sharks, skates, and rays
Skates and rays
Flattened body (countershading) Eat worms, mollusks, and other
invertebrates Can be specialized for defense
– Stingers– Electric rays
SHARKSInternal fertilization.
Viviparous = live birth
Need to be constantly swimming to keep water moving over the gills
Very highly developed sense of smell.
Covered with sandpaper-like scales called placoid scales.
Medicinal uses
Currently shark cartilage is being tested as a possible cure for cancer.
3. Class Osteicthyes
Osteo- Gr. Meaning “bone”Known as the bony fishesLargest class of vertebrates.Vary in size, shape, and structure.Complex nervous system (lateral lines)Very specialized.
Electric eel, pufferfish, angler fish, butterfly fish
Wide Variety
Structure of a bony fish
Usually four pairs of gills covered by a bony flap (operculum)
2 chambered heart Many have scales and fins Swim bladder = gas-filled sac which is
used for buoyancy (maintain depth)
Reproduction
External.A female will lay upto
500,000 eggs.The male usually swims over
the eggs depositing milt (sperm containing fluid)
The Coelacanth
A special fleshy-lobed finned fish thought to be extinct.
1938 one was caught off the southern coast of Africa.
4. Class Amphibia “from water to land” Reproduction and development must
take place in or near water. Thin moist skin Two pairs of limbs, one pair of nostrils 3 chambered heart Young show a distinct larval form.
Examples:
Frog anatomy and function
Large powerful hind legs for jumping. 2 large movable eyes Tympanic membrane 3 eyelids
– Upper– Lower– Nictitating membrane (transparent; used
for underwater sight.
digestion
Large mouth. Long sticky spade-shaped tongue Teeth along upper jaw. A pair of vomerine teeth used to hold
prey in mouth Esophagus...stomach...small
intestine(site of absorption)..large intestine...cloaca…anal opening.
Circulatory system
Oxygenated blood enters left atrium from lungs. Deoxygenated blood enters right atrium from rest of body.
Both empty into ventricle where a mixture of oxygen and non-oxygen blood is pumped out
Respiratory system
Tadpoles use gills to breathe. Adult frog uses three structures for
respiration.
Nervous system
Possess both a cranial and peripheral nervous system
Multi-lobed brain Olfactory(smell) Optic(sight) Cerebrum(voluntary muscles) Cerebellum(coordination) Medulla(involuntary muscle action)
Excretory system
CO2 excreted through the skin, other wastes filtered through the kidneys.
Urine is stored in urinary bladder then passed into cloaca and out of the body.
Reproduction
External fertilization
amplexus = male grasps female, eggs are released then quickly fertilized by the male.
Order Urodela
Salamanders and newts
Long bodies and tails
Live in dark, moist places.
Orders Anura & Apoda
ANURA Frogs and toads
APODA Caecilians Legless amphibians
Assignment
Pages 793-794
– 1-10, 14, 17, 18, 20, 23, 24, 28 Page 795 1-10