Invertebrate Zoology Lecture 17 Phylum Arthropoda Part 2

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 « T 1 – T 3 = maxillopeds « T 4 -T 8 for grasping & movement § T 4 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 « T 4 chelate « Reduction of T 8 & sometimes T 7 « Abdomen not key in movement § § Pleopod reduction Asymmetrical or tucked

Class Malacostraca § Order Decapoda: Infraorder Anomura « Hermit crabs § § § Role of reduced T 7, T 8 Asymmetry Acquiring shells Students. washington. edu

Class Malacostraca § Order Decapoda: Infraorder Anomura « Porcelain crabs § § Role of reduced T 8 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 § § T 4 -T 8 well-developed; T 4 chelate Reduced abdomen « Adaptive value?

Shore crabs Hemigrapsus nudus Pachygrapsus crassipes Hemigrapsus oregonensis

Cancer sp. crabs C. antennarius C. magister C. productus 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. Chthamalus sp. Pollicipes polymerus

Cirripedia: life cycle http: //www. jst. go. jp/erato/project/fck_P/icons/grf 1_1. jpg

Class Maxillopoda Subclass Copepoda § § § Abundant Key primary consumer Appendages « Antennae § § Long first antennae: propulsion Second antennae: feeding current « Thoracic appendages § § T 1 is a maxilliped T 2 -T 5 : periopods (swimming) « No abdominal appendages « Oil droplets: lipid reserves and buoyancy