What are choanoflagellates?
single-celled eukaryotes that are the ancestors of animals
When did the first animals begin evolving?
Before the cambrian explosion
What are appendages?
structures such as legs or antennae protruding from the body
What does the cladogram represent?
The current understanding of relationships among animal phyla
What does the non chordate invertebrate cladogram represent?
current hypotheses about evolutionary relationships among major groups of modern invertebrates
what does porifera mean literally?
pore bearers
Key characteristics of porifera
- multicellular, heterotrophic, lack cell walls, have some specialized cells
- aquatic, lack true tissues and organs, internal skeletons of spongin, spicules of calcium carbonate or silica, no body symmetry
key characteristics of cniderians
- aquatic, carnivorous, specialized tissues, radial symmetry
- tentacles have stinging cells called nematocysts for feeding
key characteristics of arthropods
- segmented bodies, jointed appendages, exoskeletons made of chitin
- coelomate protostomes with bilateral symmetry
key characteristics of nematodes
- unsegmented worms with an outer cuticle that molts
- one way simple digestive system
- protostomes with a pseudocoelum
key characteristics of annelids
- coelomate protostome worms
- segmented with internal partitions
- digestive system has two openings
key characteristics of mollusks
- soft bodies with a muscular foot
- hard shell secreted by the mantle
- coelomate protostomes with bilateral symmetry
key characteristics of echinoderms
- marine animals with spiny skin around an endoskeleton
- tube feet with suction cup ends
- water circulatory system
- coelomate deuterostomes
- 5 part radial symmetry
key characteristics of non vertebrate chordates
- no backbone
- have a nerve chord, notochord, pharyngeal pouches, and a tail that extends beyond its anus
key characteristics of fishes
- aquatic vertebrates
- paired scales, fins and gills
key characteristics of amphibians
- means double life
- live in water as larvae and on land as adults
- breathe with lungs, lack scales or claws, have moist skin that contains mucous glands
key characteristics of reptiles
- ectothermic vertebrates with dry scaly skin, lungs and amniotic eggs
key characteristics of birds
- endothermic reptiles with feathers and hard shelled amniotic eggs
- two scaly legs and wings
key characteristics of mammals
- endothermic vertebrates with hair and mammory glands that produce milk for their young
key characteristics of platyhelminthes
- soft worms with tissues and organ systems
- three embryonic germ layers, bilateral symmetry, cephalization, acoelomate
what is a larvae?
immature stages
what is a trochophore?
free swimming larval stages
what is pikaia?
the earliest chordate known from the fossil record
what is myllokunmingia?
the earliest known vertebrate
