Animals

ANIMALS πŸ”₯πŸ”₯πŸ”₯πŸ”₯

What are they?

  • eukaryotic
  • heterotrophic
  • multicellular
  • no cell walls
  • gametic life

Animals: multicellular, eukaryotic heterotrophs that feed by ingestion & don’t have cell walls

Unique Traits of Animals

  • NO cell walls!!!
  • gametic life cycle
  • all multicellular
  • asexual reproduction is rare
  • have collagen (protein in connective tissues)
  • have 2 unique cell types related to motility: muscle + nerve

Overall Phylogeny

fig 32.11

  • porifera
  • ctenophora
  • cnidaria
  • acoela
  • deuterostomia
  • lophotrochozoa
  • ecdysozoa

Key Evolutionary Steps

  1. true tissues (muscle & nerve tissue)
  2. bilateral body plan

Choanoflagellates as sister to the animals

3 lines of evidence

  1. Morphological Similarities
    • EX: collar cells (choanocytes) of sponges (EX: vase sponge) are almost identical to choanoflagellates
  2. Similar cells to collar cells have been found in other animals but no other non-animals
  3. DNA Sequence Data