Introduction to invertebrates Flashcards
Largest group of animals?
Arthropods (82.2%)
Molluscs are second largest
Earliest known predator
Invertebrate - similar to a sea anemone
What can chitin be used for?
Chitin found in crab and lobster shells can be used in batteries
When did the metazoans evolve?
875-650 MYA
Metazoans - multicellular
Dickinsonia (early animal example)
- contains cholesterol - indicator it was an animal
- 558 MYA
- around the Ediacaran period
The burgess shale
- Important indicator of complex animals
- Well preserved
- Collected by Walcott in the early 1800’s
The significance of Hallucugenia ?
Ancient animal first described upside down
when described correctly it has a similar structure to a velvet worm
Stephen Jay Gould
- loss of potential
- Author claiming that there have been no new phyla since the cambrian explosion but many phyla have gone extinct
- punctuated equilibrium
- most evolution is characterized by long periods of evolutionary stability, infrequently punctuated by swift periods of branching speciation
Simon Conway Morris
Thought that old phyla are similar to current phyla and that there hasn’t been loss but the burgess shale is a glimpse at the history of current animal phyla
Physical factors that are important in evolution
Changes in climate
Continental drift
Both linked
Who first described continental drift?
Wengener - supercontinent (Pangea) that split to form smaller continents
what are metazoans?
Animals - originated from colonial flagellate
2 types of symmetry
Radial or Bilateral
Radial symmetry (Radiata)
Identical symmetry around the central axis
E.g. Porifera & Cnidarians
Bilateral Symmetry (Bilateria)
Only two sides of symmetry (e.g. left and right)
majority of animal groups are bilateral
