Animals- Ch 33-35 Flashcards
What are the 7 characteristics that all animals have in common?
- multicellular
- cells without cell walls
- most are able to move
- diverse in form
- occupy diverse habitats
- most reproduce sexually
- have a characteristic pattern of embryonic development
- cells of all animals (except sponges) are organized into tissues and tissue layers
- heterotrophs
There are five key transitions that can be noted in animal evolution. What are they?
- ) Tissues
- ) Symmetry
- ) Body Cavity
- ) Various patterns of embryonic development
- ) Segmentation
Parazoa
- sponges
- lack defined tissues and organs
- have the ability to dedifferentiate and redifferentiate their cells
Eumetozoa
- all animals but sponges
- have distinct and well defined tissues
- have irreversible differentiation for most cell types
Do Parazoa and Eumetozoa both have symmetry?
No; parazoas do not
What is radial symmetry?
- body parts arranged around central axis
- can be bisected into two equal halves in any 2-D plane
What is bilateral symmetry?
- right and left halves that are mirror images
- only the mid-sagittal plane bisects the animal into two equal halves
What are 2 advantages of symmetry?
Cephalization (evolution of a definite brain area) and greater mobility
Eumetazoa produce three germ layers. What are they and describe them
- ) outerectoderm=body coverings and nervous system
- ) middle mesoderm=skeleton and muscles
- ) inner endoderm=digestive organs and intestines
What is the coelom?
the space inbetween tissues, surrounded by medoderm
Acoelomates
no body cavity
pseudocoelomates
body cavity between mesoderm and endoderm (called the pseudocoel
Coelomates
body cavity entirely within the mesoderm (called the coelom)
what is a blastula?
hollow ball of cells
what is the blastopore
opening to the outside
What is the difference between a protostome and a deuterstome
protostome= mouth develops first from blastospore deauterstome= anus develops first
What are 3 differences between Deuterostomes and Protostomes? (not including whether the mouth or anus develops first(
- ) Cleavage pattern of embryonic cells
- Protostomes=spiral cleavage; cells “move” as they divide
- Deuterostomes=radical cleavage; cells stay in place as they divide - ) Developmental fate of cells
- Protosomes= determinate development; embryonic cels will form specific body regions; remove 1 and development ceases
- Deuterstomes= indeterminate development; embryonic cells can develop a new individual - ) Origination of the Coelom
- Protostomes= forms simply and directly from splitting the mesoderm
- Deuterstomes= forms indirectly from the outpocketing of the archenteron
Did Protostomes evolve from Deuterostomes or did Deuterostomes evolve from Protostomes?
Deuterostomes evolved from Protostomes more than 500 MYA
Animals are divided into two main branches. What are they?
Parazoa and Eumetazoa
what does triploblastic mean
has 3 germ layers
what does diploblastic mean
has 2 germ layers
What are the two hypothesis that try to explain which group of protists are responsible for the animal kingdom
- ) the multinucleate hypothesis
2. ) the colonial flagellate hypothesis
what was the Cambrian explosion?
- enormous expansion of animal diversity in the Cambrian Period (543 to 525 MYA)
- the Hox developmental gene complex evolved
- provided a tool that can produce rapid changes in bodt plan
- most major phyla was born
Parazoa consists of only what?
Porifera (the sponges)
Diploblasts exist in two phylum. What are they?
Cnidaria and Ctenophora
What are the two major clades of protostomes
Spiralians and Ecdydozoans
Spiralians
grow by adding mass to an existing body; obvious spiral cleavage
Ecdysozoans
increase in size by molting their external skeletons
