Animal Lineages (basal)

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Animal Lineages (basal)
2010-10-18 15:21:44
key animal lineages

List of Key Lineages of the Animal Kingdom
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  1. Porifera (sponges)
    • benthic - live at bottom of aquatic environment
    • tubes/pores that create channels for water currents
    • can remold their body if the water currents change
    • have spicules (stiff spikes of silica that provide structural support)
    • suspension feeders
  2. Cnidaria (jellyfish, corals, anemones, hydroids)
    • Four main lineages: hydrozoa, cubozoa, scyphozoa, anthozoa
    • mesoglea = gelatinous material
    • one opening for both ingestion and elimination of wastes
    • sessile and medusa form
    • cnidocyte = cells eject a barbed, spear into prey, which is coated in toxins
  3. Ctenophora (comb jellies)
    • planktonic (live near surface)
    • long tentacles covered in cells that adhere to prey
    • beat cilia to move
  4. Acoelomorpha
    • lack a coelem
    • simple digestive tract
    • some only have mouth for ingestion and excretion
    • feed on detritus/small animals or protists that live in mud/sand
  5. Rotifera (rotifers)
    • lophotrochozoans
    • damp, marine, and freshwater
    • pseudocoelems
    • corona = cluster of cilia at anterior end to create current to when feeding
    • sessile
    • parthenogenesis
  6. Platyhelminthes (flatworms)
    • lophotrochozoans
    • live on substrates of freshwater/marine environments
    • some parasitize other organisms
    • high surface-area-to-volume ratio --> completely flat; diffusion across body wall
    • must be completely surrounded by water
    • blind digestive tract (one hole for ingestion and excretion)
  7. Annelida (segmented worm)
    • lophotrochozoan
    • 2 major lineages: polychaeta and clitellata

    • Polychaeta have bristle-extensions (chaetae) which extend from appendages (parapodia)
    • marine

    Clitellata lack parapodia
  8. Bivalvia (clams, mussels, scallops, oysters)
    • mollusc
    • two hinged shells
    • mostly sessile
    • fossilize readily because they live on the ocean floor
    • suspension feeding through gills (powered by cilia and siphons)
  9. Gastropoda (snails, slugs, nudibranchs)
    • mollusca
    • large muscular foot underneath
    • torsion - visceral mass rotates during development
    • have either a shell or poison
    • radula - scrapes away food
    • some use drills to break through mollusc shells, others harpoon animals with proboscis
  10. Polyplacophora (chiton)
    • mollusca
    • have plates on top to form protective shell
    • radula to feed
  11. Cephalopoda (nautilus, cuttlefish, squid, octopuses)
    • mollusca
    • well-developed head
    • foot modified to form anus/tentacles
    • highly reduced shells
    • large brains and eyes with sophisticated lenses
    • beak to bite
    • jet propulsion or moving fins to fly through water
    • spermatophore - encased sperm, fertilization occurs within female
  12. Nematoda (roundworms)
    • ecdysozoans
    • unsegmented, pseudocoelem, tube-within-a-tube body
    • gas exchange through body wall
    • move through wriggling their hydrostatic skeleton
  13. Myriapods (millipedes, centipedes)