BIOL 331
Lecture 10
Invertebrates II

 

 

Phylum Arthropoda (jointed foot)

General Characteristics 

 

Classification

 Subphylum Crustacea

Class Copepoda (copepods)

Class Cirripedia (barnacles)

Class Malacostraca (isopods, shrimp, crabs, etc.)

Subphylum Chelicerata

Class Merostomata (horseshoe crabs)

Class Pycnogonida (sea-spiders)

Subphylum Uniramia

Class Insecta (insects)

 

Subphylum Crustacea

 General Characteristics 

 

Class Copepoda 

 

Class Cirripedia (barnacles) 

 

Class Amphipoda (beach hoppers) 

 

Class Isopoda 

 

 Class Malacostraca (decapods) 

Characteristics

Examples

  • 5 pairs of walking legs
  • First pair of legs often pincers
  • Cephalothorax covered by carapace
  • Abdomen behind, often used for swimming
  • Appendages near mouth called maxillipeds
  • 2-chambered stomach
  • Centralized nervous system
Shrimp & lobsters
  • Laterally compressed
  • Mostly scavengers
  • some swim, some burrow

Hermit crabs

  • Hide soft abdomen in shell
  • + laterally compressed, coiled
  • Scavengers

Crabs

  • Dorsoventrally compressed
  • Abdomen V-shaped in males, U-shaped in females
  • Most scavengers

 

Subphylum Chelicerata

 

Class Merostomata (horseshoe crabs) 

 

Class Pycnogonida (sea-spiders) 

 


Phylum Echinodermata

General characteristics 

 

Class Asteroidea 

Characteristics

Examples

  • Usually 5 arms
  • Endoskeleton made from separate plates
  • Tube feet protrude from ambulacral groove
  • Pedicellariae on aboral surface
  • Predatory
  • Feed by extruding stomach
  • Oxygen exchange by small branching extensions of body wall
  • Can reproduce asexually & regenerate arms
  • Pisaster – feeds on bivalves & "carrion"
  • Henricia – blood star
  • Sun star, numerous arms, feeds on other stars

 

Class Ophiuroidea 

 

Class Echinoidea 

Characteristics

Examples

  • Rigid test with movable spines
  • Tube feet with suckers in five rows
  • Mouth called Aristotle’s Lantern
  • Most feed on algae
  • Some are deposit feeders
  • Oxygen exchange as for Asteroids
  • ~900 species
  • Strongylocentrotus
  • Heart urchins
  • Sand dollars

 

Class Holothuroidea 

 

Phylum Hemichordata (includes acorn worms)

 

Characteristics

 

Acorn Worms

 

Phylum Chordata

Characteristics

 

Subphylum Urochordata (tunicates)

 

Subphylum Cephalochordata

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