Class Malacostraca

• Largest in the crustacean's taxon
• Trunk composed of 14 segments: first 8 compose the thorax and the last 6 compose the abdomen
• Presence of prominent abdominal appendages in those 14 appendages
• Legs are modified for crawling, burrowing, swimming, directing, grasping, and as a secondary respiratory organ
• Some may possess vestigial appendages, which are organs that longer possess its original function but still exist.
• Female gonopore open onto the ventral side of the 5th thoracic segment while males open onto the 8th thoracic segment
• Phylum: Arthropoda

  Subphylum: Mandibulata

  Superclass: Crustacea

  Class: Malacostraca

  Order: Amphipoda

  Family: Talitridae

  Genus: Platorchestia

  Common name: Common Sand Flea

  A) Pereon

  B) Rostrum

  C) Eye

  D) Pereopods

  E) Antennae

  F) Gnathopods

  G) Pleopods

  H) Uropods

  I) Telson

  J) Urosome

  K) Pleosome

  L) Pleon

  
• Phylum: Arthropoda

  Subphylum: Mandibulata

  Superclass: Crustacea

  Class: Malacostraca

  Order: Isopoda

  Family: Oniscidae

  Genus: Oniscus

  Common name: Sowbug

  A) Compound eye

  B) Peduncle articles

  C) Antennae

  D) Flagellum

  E) Cephalothorax

  F) Legs

  G) Pleotelson

  H) Exopods of europods

  I) Pleon

  J) Pereon

  
• Phylum: Arthropoda

  Subphylum: Mandibulata

  Superclass: Crustacea

  Class: Malacostraca

  Subclass: Eumalacostraca

  Order: Decapoda

  Family: Brachyura

  Common name: Crab

  A) Chela

  B) Anterolateral teeth

  C) Swimming leg

  D) Cervical groove

  E) Carapace (shell)

  F) Dactyl

  G) Propodus

  H) Carpus

  I) Merus

  J) Lateral spine

  K) Running legs

  L) Merus

  M) Carpus

  N) Propodus

  O) Immovable finger

  P) Movable finger

  Q) Eye

  
• Phylum: Arthropoda

  Subphylum: Mandibulata

  Superclass: Crustacea

  Class: Malacostraca

  Common name: Shrimp

  A) Rostrum

  B) Antenna

  C) Eye

  D) carapace

  E) Abdomen

  F) Uropoda

  G) Telson

  H) Abdominal segment

  I) Pleopoda (swimmerets)

  J) Pereopoda (walking legs)

  
• Phylum: Arthropoda

  Subphyla: Mandibualata

  Superclass: Crustacea

  Class: Malacostraca

  Subclass: Eumalacostraca

  Order: Decapoda

  Family: Nephropidae

  Genus: Homarus

  Common name: Lobster

  A) Pereopods

  B) Abdomen segment

  C) Uropod

  D) Carapace

  E) Telson

  F) Abdomen

  G) Thorax

  H) Cephalothorax

  I) Head

  J) Cheliped

  K) Eye

  L) Antennule

  M) Antenna

  N) Cheliped

  
• Phylum: Arthropoda

  Subphyla: Mandibulata

  Superclass: Crustacea

  Class: Malacostraca

  Subclass: Eumalacostraca

  Order: Stomatopoda

  Family: Squilidae

  Genus: Squilla

  Common name: Mantis shrimp

  A) Antennule

  B) Eye

  C) Antennal scale

  D) Abdomen

  E) Carapace

  F) Antenna

  G) Maxilliped

  H) Pereopod

  I) Pereiopod

  J) Uropod

  K) Telson