Lecture 17: Phylum Arthropoda, Part 2 Focus: Marine Crustacea Invertebrate Zoology Lecture 17: Phylum Arthropoda, Part 2 Subphylum Crustacea Focus: Marine Crustacea

Lecture outline Subphylum Crustacea Overview Selected groups

Key Crustacean features Two pairs of antennae; 3 pairs of mouthparts (mandibles, 2 prs maxillae) Compound eyes, sometimes on stalks Body regions: Head and thorax often  "cephalothorax“ Abdomen Biramous appendages: thoracic & abdominal Calcium carbonate in cuticle Many have gills

Crustacea diversity: overview Differences in tagmatization Differences in appendage structure & function Is the Class Remepedia truly “primitive?”

Class Malacostraca (Subclass Eumalacostraca) Five-segmented head Eight-segmented thorax Six-segmented abdomen “Tail” = telson + uropods Carapace: partly/completely covers head & thorax

Class Malacostraca Thoracic appendages = thoracopods Maxilloped Cheliped Pereopod Abdominal appendages Pleopod

Class Malacostraca Order Euphausiacea: krill!

Class Malacostraca Order Euphausiacea: krill! Pelagic; schooling Key food resource in marine food webs Pereopods  feeding basket Compression-filtration Pleopods: swimming Ancestral to Decapoda?

Class Malacostraca Order Decapoda T1 – T3 = maxillopeds T4-T8 for grasping & movement T4 often is chelate (claw-like) Gills: base of thoracic appendages Cephalothorax covered by carapace Stalked eyes

Class Malacostraca Order Decapoda: Infraorder Caridea Shrimp “Classic” Decapoda features Most similar to early Decapoda? Compare to Euphausiacea

Class Malacostraca Order Decapoda: Infraorder Caridea Variety of local species Oregon pink shrimp! Protandrous hermaphrodites Sustainable fishery (rare) Cleaner shrimp Bay shrimp

Class Malacostraca Order Decapoda: Infraorder Palinura Spiny lobsters Similar to Caridea Common in S. California Lack powerful cheliped Protection? Group molting

Class Malacostraca Order Decapoda: Infraorder Anomura T4 chelate Reduction of T8 & sometimes T7 Abdomen not key in movement Pleopod reduction Asymmetrical or tucked

Class Malacostraca Order Decapoda: Infraorder Anomura Hermit crabs Role of reduced T7, T8 Asymmetry Acquiring shells Students.washington.edu

Class Malacostraca Order Decapoda: Infraorder Anomura Porcelain crabs Role of reduced T8 Role of abdomen Filter feeding Other behaviors and oddities

Class Malacostraca Order Decapoda: Infraorder Anomura Mole crabs Thoracopods specialized for “paddling” sand Why doesn’t it suffocate when buried?

Class Malacostraca Order Decapoda: Infraorder Brachyura True crabs T4-T8 well-developed; T4 chelate Reduced abdomen Adaptive value?

Shore crabs Hemigrapsus nudus Pachygrapsus crassipes Hemigrapsus oregonensis

Cancer sp. crabs C. antennarius C. productus C. magister C. oregonensis

Pugettia producta: shield-backed kelp crab

Reproduction: Cancer spp.

Reproduction

Class Malacostraca Subclass Eumalacostraca Order Stomatopoda: mantis shrimps

Class Malacostraca Subclass Eumalacostraca Order Stomatopoda: mantis shrimps Predatory; burrow dwellers Second thoracopod = raptorial Slicer/stabbers Smashers Gills associated with abdominal appendages Coloration threat displays mate attraction

Class Malacostraca Order Amphipoda

Class Malacostraca Order Amphipoda Laterally compressed Cephalon: head plus first thoracic segment Non-stalked eyes; compound Thoracic brood pouch Beachhopper appendages Gnathopods Some modified for jumping Pleopods Movement; respiration

Caprellid with thoracic brood pouch

Class Malacostraca Order Isopoda Idotea sp. Ligiapallasii

Class Malacostraca Order Isopoda Dorso-ventrally compressed Cephalon: head plus first thoracic segment Non-stalked eyes; compound Antennae 2 long Pereon = rest of thorax Seven pairs of similar legs Abdomen: pleopods for swimming, respiration

Class Maxillopoda Infraclass Cirripedia: barnacles Carapace covered by calcareous plates Four valves Head No antennae after settling 3 pairs of mouthparts Thorax Six pairs of biramous appendages (cirri) Long penis No abdomen Feeding

Order Cirripedia: the barnacles Balanus, Semibalanus sp. Pollicipes polymerus Chthamalus sp.

Cirripedia: life cycle http://www.jst.go.jp/erato/project/fck_P/icons/grf1_1.jpg

Class Maxillopoda Subclass Copepoda Abundant Key primary consumer Appendages Antennae Long first antennae: propulsion Second antennae: feeding current Thoracic appendages T1 is a maxilliped T2-T5 : periopods (swimming) No abdominal appendages Oil droplets: lipid reserves and buoyancy