From Biol301

• Add domains to the top of the Linnean taxonomic hierarchy
• King Paul Cried Out For Good Soup
• Kingdom->Phylum->Class->Order->Family->Genus->Species
  • Keep in mind there are other in-between levels like superfamilies and such

Contents 1 Defining an animal 2 Invertebrates 3 Three (3) Major Distinctions in Animal Evolution 4 Chordata 4.1 Dividing Chordata

Defining an animal

• All animals have four shared characteristics:

1. Multicellular
2. Heterotrophic
3. Eukaryotic
4. No cell wall

Invertebrates

• originated in the sea

Three (3) Major Distinctions in Animal Evolution

1. Tissues

• some lack true tissues, like porifora (sponges)
• others have true tissues; called eumetazoa (true-tissued); example = all non porifora

2. Symmetry

• radial symmetric animals
  • jellies or corals
  • have no front
• bilaterally symmetric animals
  • humans, sharks, planaria, all the other stuff that's not radial
  • front and back are defined; you can cut down only one axis to get "equal" halves
  • cephalizaiton is the development of a head, or an increase of concentration of nervous tissues and systems in one area of the organism

3. Development Plan

• Protostones = mouth develops first
  • Mollusks, anelids (earthworms), arthopods (blue crabs)
• Deuterostones = anus forms first
  • Vertebrates (humans) and ekynoderms (seastars)

Chordata

• humans and ekynoderms, etc.
• All memebers of chordata have 4 traits (some time in their life cycle)

1. Notochord

• A long flexible rod
• The notochord has been replaced by the skeleton in vertebrates

2. Dorsal hollow nerve chord

• For example, this becomes spinal cord and brain in humans.

3. Gill Slits

• Allows for filter feeding in Lancelates
• Developed into gills and other functions in vertebrates

4. Tail extends beyond anus

Dividing Chordata

• There are three groups of Chordata
• We learned in Nature of February 2006 that humans have a more recent common ancestor with tunicates than with lancelates as we had always believed before.

1. Lancelates

• called urochordates which is their sub-phylum name
• have all 4 traits as adults
• end up being filter feeders

2. Seasquirts

• called tunicates
• Usually an equatic animal
• Traits of Larva:
  • All four.
• Traits of Adult:
  • only gill slits.

3. Vertebrates

• have notocord in the form of a skeleton
• many examples of many combinations of the 3 other traits at different times in life