Invertebrate Phyla

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Invertebrate Phyla

• Chapter 33

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Sponges

• Sessile
• Filter feeds as water pass through wall
• No organized tissues
• Can regenerate, hermaphropditic
• Made of spongin, glass spicules, flagellated
  choanocytes lining the sponge make a water
  current into the sides of the sponge and out the
  top

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Commensalism - fish/sponge
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Cnidarians

• Stinging jelly-like tentacles
• Jellyfish, hydra, anemone, coral
• Stinging cells cnidocytes
• Radial symmetry
• Nerve net nerve cells all connect and are all
  on or off
• Two tissue layers
• Gastrovascular cavity with one opening for
  extracellular digestion
• Separate sexes, or hermaphroditic

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One opening to gastrovascular cavity
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Man-o-War, anemones, coral, jelyfish, clown
fish in anemone
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Hermaphroditismhe-she-he-she

• Two sexes on one organism
• Reproduce sexually, usually with cross
  fertilization
• (is always best ! )
• No need to find the other sex, just another
  individual

Coral spawning
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Flatworms

• Bilateral symmetry can hunt and sense
• Cephalization brain at anterior end
• Paired nerve cords
• Acoelomate body plan
• 3 tissue layers ( ect-, meso-, endoerm )
• Digestive tract with ONE opening still
• Excretory organs flame cells
• Planaria, flukes, tapeworms

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Excretory system planarian
Flame cells along excretory canals
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Non parasitic flatwormsFreshwater planarian
Marine flatworms
Penis fencing
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Parasitic flatworms- tapeworms.. and
Life cycle ---- cook your meat!
Mature proglottids with eggs
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Parasitic flukes
Life cycle always involves an alternate host that
is a SNAIL
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Parasite adaptations

• Often hermaproditc and self fertilizing with huge
  amounts of gametes
• If in hosts blood or digestive system, the
  parasite may not have a digestive system
• Hooks/suckers to attach to host
• Hard protective covering to resist host attack
• Eggs must have a way to leave host
• Often involve 2 different hosts with complicated
  life cycles ( better for long term survival )

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Roundworms (Nematodes)

• Complete digestive tract ( 2 openings )
• Pseudocoelomate body plan
• 3 tissue layers
• 2 nerve cords ( dorsal and ventral )
• Free living and parasitic

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Segmented Worms - Annelids

• Coelomate
• Segmentation body divided into small repeating
  sections..allows for specialization of segments.
• Each segment has own excretory organs
• ( nephridia)
• Closed circulatory system with hearts called
  aortic arches
• Skin or gills for breathing

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• Hermaphroditic/ cross fertilize
• Mostly marine
• Have bristles to help move

Soo segmented
Some live in tubes
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earthworm
Nephridia for excreting nitrogen waste
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Body visceral mass covered by mantle, muscular
foot
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Calcium carbonate shells secreted by the mantle
layermantle makes shell, protects organs

• Clams
• Oysters
• Snails
• scallops
• Octopus, squid ( reduced/absent/or internal
  shell

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Other mollusks facts

• Respiration by gills
• Mantle important
• Trochophore larvae similar to Annelid larva
• Closed circulatory system

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Gills -
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Arthropods

• Exoskeleton made of chitin, must molt to grow,
  protects the body
• Paired jointed appendages
• Open circulatory system
• Extremely successful group by numbers,
  diversity of habitats
• Known keys to success in nature - high
  reproductive rate with short life cycle, variable
  gene pool, a body plan that is easy to modify,
  able to adapt to variety of environments

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