- Two-chambered
- Three-chambered
- Four-chambered
- No heart
No category found.
- Fish
- Worms
- Tadpoles in larval stage
- Birds
- Bilateral symmetry
- Post-anal tail
- Pharyngeal gill slits
- All of the above
- Molluscs
- Arthropods
- Echinoderms
- Cnidarians
- A nerve net
- A dorsal hollow nerve cord
- A ventral nerve cord
- A brain only
- Flame cells
- Malpighian tubules
- Nephridia
- Kidneys
- Blood
- Hemolymph
- Lymph
- Plasma
- Fusion of segments into functional units
- Absence of a coelom
- Development of a complete digestive system
- Presence of jointed legs
- Eukaryotic cells
- Multicellularity
- Heterotrophic nutrition
- Presence of chitin
- Primates
- Carnivora
- Chiroptera
- Rodentia
- Respiration
- Flight
- Digestion
- Reproduction
- Molting
- Hibernation
- Estivation
- Ecdysis
- Skin only
- Lungs only
- Gills only
- Skin, lungs, and gills
- Sarcopterygii
- Actinopterygii
- Chondrichthyes
- Agnatha
- Vertebrae
- Fins
- Scales
- Paired appendages
- Notochord
- Dorsal hollow nerve cord
- Ventral solid nerve cord
- Pharyngeal slits
- Asteroidea
- Ophiuroidea
- Echinoidea
- Holothuroidea
- Closed
- Open
- Absent
- Double
