Vertebrate ClassesPhylum Chordata

SUBPHYLUM VERTEBRATAEndotherm: organism that can maintain a constant body temperature = warm blooded.

Ectotherm: organism that cannot maintain a constant body temperature = cold blooded.

“D-News: Ectotherm vs. Endotherm”https://www.youtube.com/watch?v=LH1p1XOqfsg“Rob & Jonny Show Episode 2: Endotherms & Ectotherms” https://www.youtube.com/watch?v=OO8eqQrzeJ0

Class Agnatha• Jawless fish – Lamprey, Hagfish

• Heart: 2 Chambers• Respiration: Gills (Hagfish – 12 pairs, Lamprey – 7pairs)

Class Agnatha• Fertilization: External• Egg: Small eggs containing a yolk sac to nourish the growing embryo. Eggs have no shell and must remain underwater to prevent drying out. •Metabolism: Ectothermic• Skin: Scales, able to secrete •mucus layer for protection

Class Agnatha• Cartilaginous skeleton• Notochord remains, vertebrae represented by individual cartilage blocks on notochord•May be parasitic or free living• Hagfish – Mouth surrounded by sensort tentacles, tongue with rasps to pull food into mouth. Scavengers• Lamprey – Circular mouth with teeth and suckers. Parasites or predators

Class chondrichthyes Cartilaginous Fish – Sharks, Skates and Rays Heart – 2 Chambers Respiration – Gills Fertilization – Internal

Male sharks deliver sperm packets with claspers (modified pectoral fins)

Eggs – Some hatch and develop inside the mother Some deposited in specialized egg cases Some live born, nourished by umbilical cord Some shark pups are cannibalistic in utero https://youtu.be/BWI60arRyG4

Class chondrichthyes Metabolism – Ectothermic (few species have endothermic characteristics)

Skin – tooth like placoid scales Streamlined for fast swimming Tough, protective body covering Lateral line system in channels in skin detects chemicals (blood) in the water and electrical signals from muscles firing

Class chondrichthyes Other Skeleton composed of only cartilage Teeth in rows Sharks must constantly swim to stop from sinking, they have no swim bladder and rely on lift from wing like pectoral fins.

Shark tissues are very oily to help maintain buoyancy Some rays are able to discharge an electric current to stun their prey, others have venomous spines on their tails.

Class OSTEichthyes Bony Fish – Salmon, Trout, Tuna, Eels, Seahorses Heart - 2 chambers Respiration - gills Fertilization - external in water (spawning) Egg – Many small eggs

Contains yolk for nourishment Must remain in water

Metabolism - ectotherm

Class OSTEichthyes Skin - Scales Other

Swim bladder to regulate buoyancy Some fish have lungs https://www.youtube.com/watch?v=tqWciuuKn3c

Wide diversity of habitats and lifestyles

Class AMPHIBIA Amphi “both” & bios “lives” - Frogs, Toads, Newts, Caecilians

Heart: 3 chambers Respiration: gills/lungs (inefficient), skin, and mouth lining Fertilization: external Egg – Many small eggs

Yolk for nourishment Must stay moist in water, mud or carried by mother

Metabolism: ectotherm

Class AMPHIBIA Skin - Smooth, moist skin

Some have poison glands Other

Most undergo metamorphosis Some croak or chirp to communicate Some frogs have teeth and claws Tongues attached at the front of mouth Caecillians – limbless, live underground in caves, mostly blind

Class REPTILIA Reptiles – Snakes, Turtles, Lizards, Alligators Heart: 3 chambers Respiration: lungs & ribcage (to protect the lungs) Fertilization: internal Egg – Few large eggs

Hard shell (so won’t dry out on land) Yolk for nourishment

Metabolism: ectotherm

Class REPTILIA Skin - Scaly, dry, leathery skin

Skin reduces water loss Other:

Skin must be shed as they grow O2 & CO2 exchanged through the shell so embryo can breathe

Some posses venom glands and fangs Turtles and tortoises have large shell for protection

Class AVES Birds Heart: 4 chambers Respiration: lungs, ribcage, alveoli (to increase gas exchange)

Fertilization: internal Egg – Few large eggs

Hard protective shell Yolk for nourishment

Metabolism: endotherm

Class AVES Skin: covered with feathers Other

Special features for flight Archaeopteryx = first bird in fossil record, links reptiles & birds

Class Mammalia Heart: 4 chambers Respiration: lungs, ribcage, alveoli, diaphragm Fertilization: Internal Egg – Small, fertilized and develop inside mother

Live bearing (viviparous) Exception: monotremes (egg laying mammals)

Metabolism: endotherm

Class Mammalia Skin - covered with fur or hair

may have sweat glands to maintain internal temperature Other:

Mammary glands: produce milk to feed young Extinction of dinosaurs allowed mammals to diversify Three reproductive orders