Bio - Animals

• first animals originated from a single-celled organism called a protist called a eukaryote (800 million years)
• Characteristics of animals

  • Heterotrophy
  • multicell
  • no cell wall
  • diverse form
  • sexual repro
  • embryo
  • tissues
• Animal innovations

  • symmetry
  • Tissues
  • Body cavity
  • segmentation
  • embryonic development
• radial symmetry 


  arranged in central axis

  
• bilateral symmetry 


  right and left (human)

  
• bilateral advantages compared to radial

  • Cephalization (brain)
  • directional movement
• tissues

  zygote are totipotent
• Totipotent 


  Give rise to all body cells
• Acoelomates

  No body cavity
• Psuedomates

  Body cavity between meso and endosperm
• coelomates

  body cavity entirely lined with mesodermal tissue
• open circulatory system

  Blood pumps and mixes with fluids and re enters the vessels
• closed circulatory system

  blood pumps moves separately from body fluids aka humans
• Embryotic development

  Miotic cell divides (cleavage) of the egg forms hallow ball of cells carred blastula
• blastopore

  opening to the outside looks like a pushed in ballon
• archentron

  primitive body cavity
• bilateral are divdied into two groups

  • protostomes
  • deuterostomes
• Protostomes

  • mouth first
  • spiral cleavage (don’t line up)

  can be divided into two groups lophotrochozans and ecaysonaz
• lophotrochozoans


  grow by gradual additional body mass
• ecaysoanz

  • molt
  • contains arthropods
  • cell know what they are going to be early on
  • cells grow left and right of new cells
• hox genes determine

  • body pattern
  • body plant
• Parazoans

  • lack of tissue aka sponges (monophyletic)
  • can be divided into two branches
  • no symmetry
• phylum porifera

  they are part of the parazoans

  they have 3 layers and contains a epithelium a mesonyl and have a lining in the interior cavity
• Porifera reproduction


  asexual due to fragmentation

  sexual due to sperm

  • sperm is captured then passed to egg in mesonyl can sometimes develop in mom or in water
  • larvae turns into planktonic then into adult
• eumetazoans

  has tissues and are bilateral they contains layers that later turn into organs

  • inner endoderm = gastrodermis (digestion)
  • outter ectodermis = epidermis and nervous sys
  • middle mesoderm = muscle (only in bilateral)

  can be both radial and bilateral

  if it has all three layers its called tripoblast and if it only has two its called deptroblast
• Deuterostomes

  • Ass first
  • radial cleavage
  • forms on top of cells
  • more uniformed
• Cteneophora contains Cnidaria who are marine animals as well as diploblast with endo and ecto but with no organs some do contain nematocyst which allowes them to capture prey and carry venom in epidermis although it’s unknown what it is they come in 2 forms

  • polyps - cylidrial and sessile
  • medusa - umbrella and free- living
• Anthozoa ; corals


  nemo house

  • solitary polyp
  • hallow
  • dinoflagellates for photosynthesis
  • economically important
• Cubozoa ; box jellies

  • Strong swimmers
  • predetors
  • stings can be fetal
• hydrozoa ; hydra/ man of war

  • both polyp and Medusa forms
  • only class with freshwater members
• scyphozoa ; jelllyfish

  • Medusa more conspicuous and complex
  • ring of muscle helps pulpulsion
• staurozoa ; star jellies

  • resembles Medusa in most ways but is attached by stalk that emerges from side of the opposite mouth
• ass first

  Deuterostomes
• molting animals

  ecdysozoans
• symmetrical animas


  eumetazoans
• Lophotrochozoa segmented worms

  annelida
• Lophotrochozoa snails and squid animals

  mollusca
• Dueterostomes spiny skin


  Echinoderma
• deuterostomes bilateral spiral clevage acoelomate flatworm 


  platyhelminthes
• deuterostomes bilateral spiral clevage 


  lophotrochozans