Animals After fertilization, Cleavage begins as the cell divides. Gastrulation – The formation of the embryonic germ layers during embryo development. Blastopore – An opening that develops in the blastula. Deuterostomes – Blastopore develops into the anus. Ex. Echinoderms and chordates. Protostomes – Blastopore develops into the mouth. ex. Mollusks, arthropods and annelids - Ectoderm – Outermost layer. Develops into epidermis, nervous system, external sense organs, and the mucous membranes lining the mouth and anus.

Animals Mesoderm – The middle layer of cells that gives rise to muscles, blood, and various systems. Endoderm – The innermost germ layer that develops into the epithelium of the pharynx, respiratory tract, digestive tract, bladder and urethra.

Vertebrate Characteristics Vertebrates are chordates that have a dorsal nerve cord. Classes of vertebrates include fishes, amphibians, reptiles, birds, and mammals. All vertebrate classes except fishes spend part or all of their life on land. Many characteristics of terrestrial vertebrates are adaptations to life on land and fall into two broad categories: support of the body, and conservation of water.

Amphibians (Frogs) 3 chambered heart 2 atria and 1 ventricle. Blood still mixes when it goes to the lungs and the body

3.5 chambered heart (crocs have a 4 chambered heart) 2 atria Reptiles 3.5 chambered heart (crocs have a 4 chambered heart) 2 atria 1.5 ventricles with a septum partially dividing the sides Septum helps to separate the oxygen rich and oxygen poor blood Oxygen poor blood goes to the lungs to be oxygenated and then back to the heart to be pumped to the body

The Amniotic Egg A big moment in evolution!! Allowed for fetal development out of water

Three patterns of reproduction Oviparity - Female lays fertilized eggs Most reptiles, all birds & 3 species of mammals Ovoviviparity – Fertilized eggs remain in body for a short time. Pit vipers, some shark Viviparity – No shell forms & young retained in body until mature. Oxygen and nutrients are transferred across a placenta Placental mammals

Mammals Endothermic Hair 4 chambered heart Double pump Mammary glands Extensive care given to young Lungs Specialized teeth (incisors, canines, premolars and molars)

The Human Heart