branched gastrointestinal cavity that diffuses nutrients

eyespots that detect light, simple brain with nerve cords extending down body

Hermaphroditic, may swap sperm or reproduce asexually

Bilateral and segmented body

Closed circulatory system: blood travels to and from the heart

open circulatory system

Gills (in water) or lungs (terrestrial)

mantle, visceral mass, foot

Appendages for walking (legs) and swimming (swimmerets)

Metamorphosis: allows different life stages to not compete for resources

exoskeleton to conserve water while on land

Swim bladder for bouyancy

have lungs and can breath without swimming (operculum)

Lateral line system to detect prey from vibrations

Larger bones for weight bearing

Still utilize aquatic environment for reproductive stages

First tetrapods: four limbs for walking on land

Distinct neck for independent movement

Larger and more complex lungs for breathing air

Changes in inner ear to detect airborne sounds

three part body plan: head thorax and abdomen

evolution of wings for better disperal

Respiratory system that conveys air from the insect's surface to the inside of the body.

Endotherms-maintain their body temp internally through their metabolism.

Amniotes: have eggs that survive on land because they are enclosed in a fluid series of membrances

larger eyes, bigger brains

Hollow bones (light weight)