Invertebrate Body Plans

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Invertebrate Body Plans

• Or . . . Hey! Lets try this!

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PORIFERA (SPONGES)

• Mostly marine
• Asymmetrical
• Sessile (attached)
• Hollow body
• Lots of pores (PORifera)

Barrel sponge
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• All systems supported by flow of water through
• the sponge

• Water pulled in thru
• pores by flagellated cells
• Single large opening
• (osculum) H2O exits

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• Spiny spicules embedded in spongin that give
• it shape (a skeleton)

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Phylum CnidariaSea Jellies, Anemones Corals

• Soft-bodied carnivores
• 2 tissue layers
• Hollow gastrovascular cavity (one opening)
• Hydrostatic skeleton
• Epidermis outside, gastrodermis inside

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• Contain nematocysts (stinging cells) that release
  toxin to paralyze/kill prey
• Hydrostatic skeleton allows some movement in
  anemones and corals
• Sea jellies contract muscles to move via jet
  propulsion
• 2 body plans medusa polyp

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Corals each opening is a separateanimal called
a polyp

• each polyp builds a CaCO3 covering

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• Together they form
• the reef
• Rainforest of the sea
• Enormous diversity
• Many ecosystem
• services

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Flatworms (Phylum Platyhelminthes)

• 13,000 species
• Bilateral symmetry and cephalization
• Acoelomates
• Simplest animal w/ 3 tissue layers
• Movement - hydrostatic skeleton!
• Can be parasitic or free-living

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Tapeworms!
nuf said . . .
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Roundworms (Phylum Nematoda)

• 1st specialized tissues/organ systems!
• Bilateral Symmetry, cephalization
• Pseudocoelomates
• Slender w/ tapering ends
• Hydrostatic skeleton and longitudinal
• muscles - thrashing movement
• Parasitic or free-living
• Hook and pin worms, filarial (live in lymph
• and blood of hosts)

• Microscopic to 1 m long

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Phylum Annelida - segmented worms

• Bilateral symmetry, cephalization
• coelomates
• Segments separated by septa (walls b/w
• segments)
• Hydrostatic skeleton
• Each segment has own
• muscles inching movement
• Setae - hairs or bristles
• Earthworms, leeches,
• marine worms
• (polychaetes)

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PHYLUM MOLLUSCA
MANY variations!
gastropods
cephalopods
bivalves
slugs . . .
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PHYLUM MOLLUSCA

• Bilateral symmetry, coelomates, some
  cephalization

• Soft body w/ external or internal shell (lost in
• some)

• Foot - locomotion, modified for crawling,
• burrowing, grasping (tentacles)
• Visceral mass (digestive, excretory,
• circulatory and reproductive organs)

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Incurrent siphon

• Mantle - epidermal covering that secretes . . .
  
• Calcareous shell

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Mollusca (contd.)

• Bivalves
• Clams, mussels, oysters,
• scallops
• Two shells held together by
• powerful muscles
• Move by jet from siphon or burrow w/
• modified foot

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Mollusca (contd.)

• Gastropods (stomachfoot)
• Snails, slugs, sea butterflies
• Shell-less or single shelled
• Move by crawling w/ muscular foot

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Mollusca (contd.)

• Cephalopods (headfoot)

• Head attached to single foot
• Foot modified into tentacles (arms)
• Shell internal or not at all (except for
• nautilus)
• Nautilus, octopi, cuttlefishes, squid

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PHYLUM ARTHROPODA

• 6-9 MILLION SPECIES
• 80 of animal species
• live in ALL enviros
• tolerant of extremes

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Phylum ARTHROPODA

• Bilateral symm., cephalization, coelomate
• Hard exoskeleton (chitin), muscle attachment for
• movement
• Specialized body segments (head thorax or
• cephalothorax w/ abdomen)
• Jointed appendages legs and antennae complex
• movement
• Classified by
• body segments and appendages
• specialized mouth parts

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ARTHROPODS (Crustacea)

• Crabs, lobsters, crayfish
• Two or three body segments
• 2 sets of antennae
• Pincers called chelipeds

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• ARTHROPODS (Class Arachnida)
• Spiders, mites ticks
• 2 body segments (head and body)
• 8 legs
• No antennae

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ARTHROPODS (Class Insecta)

• Body divided into head, thorax, abdomen
• 3 pairs of legs

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Centipedes, Millipedes and Horseshoe Crabs
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Phylum ECHINODERMATA
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ECHINODERM BODY PLAN

• First deuterostomes!
• Radial symmetry
• Spiny skin ( echinoderms)
• Endoskeleton - tube feet movement
• Adults have no head or brain