PHYLUM CHORDATA Definition: phylum of the animalia kingdom comprising all the animais that have, at some stage in their life, a notochord, pharyngeal slits and a muscular tail extending past the anus - Examples of organisms: Traits that make it unique:
Includes vertebrates (fish, amphibians, reptiles, birds, and mammals.)
Organisms have...
...a stiff dorsal rod that helps to organize the embryo’s development. ...the central nervous system (brain and spinal cord) that is tubular ...their sides with slits just behind the head. These pharyngeal slits (pharynx means “throat”) becomes gill slits of adult fish. In air-breathing chordates, they develop into various organs such as internal parts of the ears ...a tail. FUN FACT: In humans, the it’s the tailbone, or coccyx, which curls internally.
5 Classes within Chordata: 1). Reptilia: over 7000 species, possess adaptations towards independence from H20, scales include keratin (waterproofing protein which prevents water loss in organism), possess an amniotic egg and internal fertilization, ectotherms 2). Mammalia: have hair, made of keratin, which aids in maintaining body temperature. They are endothermic creatures, who have very efficient respiratory and circulatory system (including diaphragm). Most possess placentas and give birth to live young. 3). Amphibia:first vertebrates to inhabit land, most are 4 limbed, include frogs, salamanders & caecilians 4). Fish (Agnatha, Chondrichthyes, Osteichthes, etc): All fish. Skeleton material varies through bones and cartilages. All possess some form of segmented vertebra. 5). Aves: evolved from dinosaurs, almost all adaptations are made for flight: presence of feathers, made of keratin, forelims developed into wings. There is absense of some organs (EX: females usually have 1 ovary). They are endothermic organisms and have very efficient lungs. Reproduction is through hardened amniotic eggs and they perform brooding, which is the warming of the eggs done by parents.