Invertebrate

What is an invertebrate?

• Any animal without a backbone
  

What percentage of all marine life are invertebrates?

• >90%
  

How many key phylums of invertebrates are there?

• 8
  

Porifera:

• Sponges
• Simple multi-cellular organisms with no true tissue layers or organs.
  
• Sessile/non-moving.
• Pore bearing.
• Filter feeders.
  

Cnidaria:

• Corals, Anemones, Jellyfish, Hydroids
• Radial symmetry
• Polyp/Medusa stages
• Nematocysts
• Nettle cells
• Carnivorous
• Jellyfish eat 10x their body weight, daily
• Nerve net
  

Ctenophora:

• Comb jellies
• Lacks stinging cells and possesses comb like cilia
• Coloblasts
• 95% water
• Effective predators
  

Platyhelminthes:

• Flatworms
• Slow moving worms
• Size can range from 1-5 inches
• Can be confused with nudibranchs
• Nudibranchs - shell-less snails
• Flattened and leaf like
• Bilateral symmetry
• 3 cell layers
• Brightly colored
• Mostly carnivorous
  

Annelida:

• Segmented worms, Fire worms, Feather Dusters, Tube worms
• Segments each contain the same organs
• Share a common gut, nervous system, and circulatory system
• Septa separate segments internally
• Annuli separate segments externally
  

Mollusca:

• Snails, Slugs, Squid, Octopus, Clams, Oysters, Chitons
• All have mantle, shell, and muscular foot
• 2nd most abundant marine invertebrate phylum
• Octopus and squids have a siphon as opposed to a muscular foot for movement
  

Arthropoda:

• Shrimp, Lobster, Crabs, Barnacles, Horseshoe Crab
• "Jointed foot"
• All members body plan made up of: head, thorax, and abdomen
• Exoskeleton
• Segmented bodies
• Pairs of legs
• Horseshoe Crabs have blue blood
  

Echinodermata:

• Brittle stars, Basket stars, Sea Urchins, Sand dollars, Sea Stars, Sea Cucumber
• All echinoderms are marine organisms
• Hard internal skeleton covered by a think skin and tube feet
• 5 point body plan
• Radial symmetry
• Water vascular system
• Regenerative capabilities