Emergence of the Animal Kingdom
Or “Rise of the Chordates” Phylum Chordata Leading to Subphylum Vertebrata
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Chordates include the following:
1. 2. 3. 4. 5. Fish Reptiles Amphibians Birds Mammals
Chordates
– 4 characteristics 1. notochord - support 2. post-anal tail 3. pharyngeal gill slits 4. dorsal hollow nerve cord
Chordate Characteristics
Gills in Humans! – check it out
Tunicates are Chordates!
Sea Squirts
• sponge like - filter feeder •larva free swimming, bilateral with all Chordate traits
• Lancets (a primitive fish like organism) closely resembles the idealized chordate. – The notochord, dorsal nerve cord, numerous gill slits, and post-anal tail all persist in the adult
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“Ontogency Recapituates Evolution” Evolution Playing out in Fetus…
(all these Chordates (birds, mammals, reptiles, fish, have strikingly similar Embryonic Development)
Chp 33 – Rise of the Mammals
• Definition of a Mammal: 1. Homoeothermic – meaning that mammals produce their own body heat 2. Mammary tissue - for the production of Milk 3. Hair Follicles - for the production of Hair 4. Generally, internal fertilization and harboring of young, however, this is only a generality because not all young are “cooked” to term internally.
Monotremes – an Order of Class Mammalia
Monotremes
eg. The Platypus, which has a BILL, lays EGGS, but still has mammary glands and produces MILK for young. This suggests a relationship between REPTILES, BIRDS and mammals. Imagine that?
Marsupials
– eg. The Kangaroo, which is a non-placental mammal.
Here, the development of the young is very complex, and a baby kangaroo is born very “uncooked”, and must crawl into the mother’s pouch and latch onto a nipple to receive milk to continue development. You might say, baby Kangaroos or “Joey’s” get a womb with a view
Kangaroo Birth
17 Weeks
Placental Mammals
– eg. You – well if you’re female, anyway. Internal Fertilization development of young to a highly Advanced stage.
The Placenta is Key
In Mammals, all the Major Body Systems are online and advanced
Skeletal System
Muscular System
Advanced Circulatory System
Respiratory System
Nervous System is online and advanced!
Excretory System – ooo look, Kidneys!
Endocrine System – Controls you Hormones
Lots of Mammals in the Simpsons
Lastly, we can Learn Important Lessons from Mammals like Homer