- Cnidaria
- Platyhelminthes
- Porifera
- Nematoda
No category found.
- Tissue level
- Organ level
- Cellular level
- Organ system level
- Earthworm
- Starfish
- Flatworm
- Roundworm
- Laying eggs
- Giving birth to underdeveloped young in a pouch
- Presence of a placenta for fetal development
- External fertilization
- Laying eggs
- Giving birth to underdeveloped young that complete development in a pouch
- Fully developed live birth
- Absence of mammary glands
- Lay eggs
- Give birth to live young
- Have pouches
- Are aquatic
- Reptilia
- Aves
- Mammalia
- Amphibia
- Heavy bones
- Absence of feathers
- Pneumatic bones and feathers
- Cold-bloodedness
- Reptilia
- Aves
- Mammalia
- Amphibia
- Amphibia
- Reptilia
- Aves
- Mammalia
- Gills only
- Lungs only
- Skin, lungs, and gills (in larvae)
- Trachea
- Chondrichthyes
- Osteichthyes
- Amphibia
- Aves
- Osteichthyes
- Chondrichthyes
- Amphibia
- Reptilia
- Chondrichthyes
- Osteichthyes
- Agnatha
- Amphibia
- Urochordata
- Cephalochordata
- Vertebrata
- Hemichordata
- Locomotion
- Feeding and respiration
- Sensory perception
- Support
- Brain and spinal cord
- Notochord
- Vertebral column
- Muscles
- Spinal cord
- Vertebral column
- Skull
- Rib cage
