tunicates “tail cords” – over 2,000 species adults sessile free swimming larvae; only larvae...
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4 Defining Characteristics1. Notochord - extends through
length of the body as a simple skeleton
2. Dorsal, hollow nerve cord3. Pharyngeal gill slits4. Muscular postanal tail
Three SubphylumUrochordata
TunicatesCephalochordata
Lancelets
VertebrataFishAmphibiansReptilesBirdsMammals
Tunicates“Tail Cords” – over 2,000 species Adults sessile Free swimming larvae; only larvae have a 4 defining characteristics
SUBPHYLUM UROCHORDATA
Lancelets “Head-Cords”tiny marine animalsretain all 4 characteristics into adulthoodNotochord, pharyngeal slits, dorsal hollow nerve
cord, post anal tail
led to vertebratesFilter Feeders
SUBPHYLUM CEPHALOCHORDATA
SUBPHYLUM VERTEBRATA
5 Classes1st vertebrates, aquaticGenerally characterized by scales, fins and pharyngeal gills
Exothermic (Ectothermic) – no internal body temperature regulation
Fish
Circulationclosed circulatory system with a 2 chambered
heart. Reproduction reproduce through external fertilization -
spawning
Jawless FishHagfish (Class Myxini) and Lampreys
(Cephalaspidomorphi)Lack vertebrae (hagfish) or have incomplete vertebral
column (lamprey)Predators that attach to the side of a fish with
modified mouthHave no scales
Hagfishno vertebraehas a skull
Class ChondrichthyesCartilage fishSharks, skate, rays and
sawfishPrimitive Older fishMost have to swim to
breathe
Bony FishRay finned fish (Class
Actinopterygii ) - - most common fish- have jaws and paired fins- fins supported by rays fanning our from central bone
Lobe finned fish (Class Sarcopterygii)- fins supported by central axis bone- ancestors of amphibians
Walking Fish - Grunion
Class AmphibiaFrogs and salemandersAquatic as larvae, after metamorphosis, live
on land as adults.Have moist skin with many glandsmust be moist to breathe; respirate through
skinevolved from fish 360 myaexothermic
CirculationAmphibians have a double-loop circulatory
system with three-chambered heart.ReproductionFertilization is external Shell-less eggs must be laid and fertilized
in water
Class ReptiliaInclude 3 groups: snakes, turtles, crocodiles Fully adapted to life on land
Amniotic egg scaly skin (prevents loss of moisture) Exothermic - regulate their body temperatures by basking in the sun, burrowing in the ground. Soaking in water etc…
Circulationmore efficient circulatory and respiratory
systems (lungs, 3 chambered heart).Reproduction internal fertilizationLay fluid filled amniotic egg covered with a
protective shell
Class AvesMost are adapted for flightCovered with feathershollow bones2 legs for walking, 2 modified for wings
Birds are endothermic - generate body heat internally by their own metabolism.
Circulation4 chambered heart; allows for efficient
delivery of O2 to cells.Reproduction internal fertilization. incubate eggs and feed young have amniotic eggs (keeps eggs moist)
Fossil evidence shows that birds evolved from the same line as crocodiles and dinosaurs.
Class MammaliaCharacteristics:hair - insulation, camouflage,
sensory device, waterproofing, signaling and defense
mammary glandsEndothermic
Circulation4 Chambered heartRequire a constant supply of
nutrients and oxygen to maintain homeostasis and metabolism
Keeping blood separate makes the delivery of nutrients and oxygen more efficient.
ReproductionInternal fertilization
1. Monotremes - young develop in shelled eggs;
Ex. spiny anteater and duck-billed platypus
2. Marsupial - young leave mother’s body to pouch before development is complete.
Ex. kangaroo and opossum
3. Placental - young develop completely within the uterus of the female
Ex. Human, whales, giraffe etc…
3 Types