Animalia Vertebrates

Animals Animals are spilt into two major groups: Vertebrates Invertebrates

Vertebrates Agnatha Chondrichthyes Osteichthyes Tetrapoda Aves These are animals with a backbone. There are six groups of vertebrates: Agnatha Chondrichthyes Osteichthyes Tetrapoda Amphibians Reptiles Aves Mammalia

Agnatha Jaws are absent. Paired fins are generally absent. In most cases the skeleton is cartilaginous. The digestive system lacks a stomach. Includes: Lampreys Hagfishes

Chondrichthyes Lack true bone Have a skeleton made of cartilage May have calcified teeth and bone but these are structurally different to true bone Have jaws with teeth Lays eggs (oviparous) or give birth to live young (viviparous) Have paired fins Live in water Mostly marine, 5% live in freshwater Includes: Sharks Skates rays

Rays vs skates Rays One lobed pelvic fin Usually have dorsal fins Stinging spine Skates Two lobed pelvic fin No dorsal fins No stinging spine

Osteichthyes Bony fishes Have true ossified bone Usually have some form of skull Wet scales Most have swim bladders Two major groups: Ray finned & lobe finned

Wet vs dry scales Wet scales Dry scales Aquatic organisms: fish Are derived from skin May contain bone and enamel May grow in concentric layers Are “designed” to reduce drag through water Dry scales On reptiles, arthropods and birds Are generally ridged Can be derived from hair Are usually keratinous Are to prevent wear from friction

Tetrapoda Includes amphibia and reptilia Are four legged vertebrates have evolved into mammals Pentadactyl limb

Commonality in Tetrapods

Amphibia Have moist skin Lay jelly coated eggs in water Lives on land and water Evolution of lungs Two circuit circulatory system Undergo metamorphosis Includes: Frogs & toads Salamanders newts

Frogs vs Toads Order Anura Longer jumping legs Eggs in clusters Moist, smooth skin Prefer moist environments Have vomerine teeth in upper jaw Eyes bulge Order Anura Shorter walking or hopping legs Eggs in chains Some give birth to live young Dry bumpy skin Dryer environments No teeth Eyes don’t bulge

Mexican Walking fish (axolotl) Is not a fish but an amphibian Undergoes a condition called Neoteny Is a reduced rate of development to the point where the juvenile doesn’t develop into an adult The adult stage retains the form of the juvenile. The axolotl is a large tadpole. In some cases the axolotl will metamorphose into an adult version similar to a tiger salamander

Reptilia Have dry scales Lay leathery shelled eggs (some species give birth to live young) Some have a form of placenta All have lungs Cold blooded Includes: Turtles & tortoises Crocodilians Lizards Tuatara (NZ)

Evolution of Bipedalism Graviportal Mediportal Cursorial

Aves Have feathers and hollow bones Lay hard shelled eggs Warm blooded Skeleton approximately 5% of total weight (humans approx. 15%) Feathers weigh approximately 6% of total weight Lay hard shelled eggs Warm blooded No teeth* Highly advanced respiratory system Includes:

Mammalia Hair Mammary glands teeth Auditory ossicles Neocortex Four chambered heart Sweat glands Most give birth to live offspring (vivparous) Warm blooded

Kangaroos vs Wallabies Are both macropods (f. macropodidae) Primarily size-based Kangaroos – longer legs for speed Wallabies – shorter legs for manoeuvrability Different dentition and head shape Kangaroos tend to have dull coats

Summary of Vertebrates (Chordata)