Phylum Arthropoda Subphylum Crustacea by WNudkeoO


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 Phylum Arthropoda
Subphylum Crustacea
   Terrestrial and aquatic
   All depths in marine, brackish, and
   > 67,000 described species, likely 5-10x
    that number no yet described
   Diverse form, size, and habitat
   5 classes, 34 orders
   Head = 5 segments, trunk divided into
    thorax and abdomen
   Carapace or cephalic shield
   Appendages multi-articulate; either
    uniramous or biramous
   Mandibles are modified limbs that function
    as jaws
   Gas exchange by diffusion across
    specialized surfaces
   Excretion by nephridia
   Simple and compound eyes in at least one
    life cycle stage
       Compound eyes on stalk
   Gut with digestive cecae
   Nauplius larvae, either mixed or direct
   2 pairs of antennae
          Crustacean Bauplan
   Thorax
     anterior   segments fused = cephalon
                   additional mouthparts
       Maxillipeds:

       Number of segments in thorax varies

       Thorax appendages = pereopods
          swimming, walking, gas exchange, feeding,
          ultiarticulate and biramous
        Basic Crustacean Bauplan
   Abdomen
       Segments
       Number of segments used in ID
            Appendages = pleopods
                 Biramous, flap-like
                 swimming
       Culminate in telson
          Anus
          caudal rami
          w/uropods (last pair of abdominal appendages) forms
           tail fan
Adult Crustacean
              Crustacean Bauplan
   Nauplius Larvae
     Single, median, simple eye
     3 pairs of sectioned, functional limbs
           Become antennules, antennae, and mandibles
   adult Crustacean diagram:
   Open circulatory system
       Dorsal ostiate heart
       Internal organs bathed in fluid
       Simple heart and vessels in most
            Sessile species no heart; pumping vessels
   Blood
       Variety of cell types
          Dissolved hemoglobin or hemocyanin
          Explosive cells release a clotting agent at injury sites
            Heart Shape
 Heart long and tubular; to
  postcephalic region
 Or, globular, box shape, in thorax;
  association with thoracic gills
Gas Exchange
   Aquatic
     Small organisms = diffusion
     Concealed gills for protection, prevent
     External gills
         Modified thoracic limbs
         Gills are thin; maximize gas exchange

         Most species beat gills to maintain flow
                   Gas Exchange
   Terrestrial
      Cutaneous Respiration

         Membranes on legs of some species

      Gills

         Concealed

      Pseudotrachea

         Internal blind sacs to outside through small pores

         Air in sacs, gas exchange with blood

         Internal gills moist
   Water currents
   Hydraulic vacuum
   Filter feeding
   Feeding basket
   Passive
   Twirling antennae
   Direct manipulation
   Sand grazers or Sand lickers
   Predators
   Parasitism
            Water Currents
Thoracic limbs for swimming and creating
  suspension feeding currents
 Water drawn into space
 Particles trapped by setae
 moved to food groove and toward head
          Hydraulic vacuum
   Mouth appendages = paddles

   Water containing food drawn into interlimb

   Food particles are not filtered, but captured in
    small parcels of water

   Individual algal cells are captured this way
                  Filter feeding

   Sessile crustaceans have feathery cirri to filter
   food up to one mm
   = detritus, bacteria, algae and various
   Some can coil cirrus around large prey in a
    tentacle fashion
    Filter feeding in slow water

 Extend pairs of cirri like a fan
 Sweep rhythmically through water
    Filter feeding in fast water

 Allow water to run through filter
 video
                Passive feeding
   Use cirri to passively strain
   Burrow into sand with anterior facing
   Extend cirri to capture bacteria, protists
    and phytoplankton
   Antennae brush food towards mouth
              Twirl antennae

   Create spiraling currents that bring food
    toward mouth
   Food entangled in setae near base of
    mouth, brushed in
           Direct manipulation
   Manipulation by mouthparts, pereopods
    and subchelate anterior legs
    Sand grazers or Sand lickers
   Brush sand grains with setose mouthparts

   Select individual sand grain, rotate and
    tumble against mouthparts to remove
    organic material
   Grab prey with chelae pereopods
   Tear, grind and shear with mouthparts

   Hunters or ambushers use raptorial
    subchelae to stab, club or smash prey

   Some hold prey in cage using endopods;
    others inject and suck out tissues
            Snapping Shrimp
   Use large cheliped to snap close:
    produces loud popping sound and “shock”

   Pressure wave stuns prey, pull into burrow
  Snapping Shrimp Video
               Digestive system
   Foregut
     Lined with cuticle that is continuous with
      exoskeleton, molted
     Short pharynx-esophagus, stomach

     Stomach = chambers for storage,
      grinding and sorting
   Midgut
     intestine

     Length varies with body shape and
      size, diet
     digestive ceca

 Hindgut

  Short,   to anus
   Foregut functions
     transport food to midgut and/or processing by
      chemical digestion
     cardiac stomach = storage, bits are moved
      past gastric mill (sclerotized teeth for grinding)
     pyloric stomach = filter large particles

   midgut, hindgut and anus
    Excretion and Osmoregulation
   Ammonia by nephridia and gills
   nephridial excretory organs as antennal
    glands (green glands) or maxillary glands

   Inner blind end is coelomic remnant of
    nephridium = sacculus
   Actively remove and secrete material from
    blood into excretory lumen

   metabolic waste removal and water and
    ion balance
           Other osmoregulation
   Thin areas of cuticle
       Gill surfaces
   terrestrial isopods: ammonia diffuses from
    the body as gas
    Nervous System and Sense Organs
 Brain: three fused ganglia

 Primitive nervous system = ladderlike
      Nervous System and Sense Organs

variety of sensory receptors
 innervated setae or sensilla: contain
  mechanoreceptors and chemoreceptors

   Propioceptors

   Animals in Class Malacostraca: statocysts
      Nervous System and Sense Organs

   Two rhabdomeric photoreceptors:
       Median simple eyes
       Lateral compound eyes
   Most possess both, either simultaneously
    or during development

   Naupliar eye = primitive, secondarily lost
    Nervous System and Sense Organs

Lateral compound eyes
 Lack visual acuity

 Discern shapes, patterns and movement

 Color vision in some

 Lacking in many taxa
      Nervous System and Sense Organs

Underwater vision
 Problems with angular distribution of light, lower
  intensity, and narrow range of wavelengths than
  in air

   Solution: Mount eyes on stalks, increase
    information available to eyes. Increases field of
    view, and binocular range
      Nervous System and Sense Organs

Complex Endocrine and Neurosecretory
   Not well known

   Molting, chromatophore activity, and
    reproduction under hormonal and
    neurosecretory control

   Bioluminescence in several groups
      Reproduction And Development

 Exploit virtually every life history scheme
 Usually dioecious

 Hermaphroditism in remipedes,
  cephalocarids, cirripedes, few decapods
 Parthenogenesis common among
  branchiopods and certain ostracods
      Reproduction And Development

Reproduction Systems
 Gonads paired structures in trunk

 Pair of gonoducts from gonads to genital
  pores on trunk segment
 Male pair of penes, or single fused median
 Female include seminal receptacles
         Reproduction And Development

   Most crustacea copulate

   courtship behavior

   Pairing more or less permanent, or seasonal
        Reproduction And Development

Fiddler crab example
Males use cheliped waving to attract females, repel
   competing males
Males produce sounds by stridulation, substratum
   thumping to attract mates
Mating when male entices female into burrow
      Reproduction And Development

Reproductive systems continued
 Sperm transferred either loose in seminal
  fluid or packaged in spermatophores
 Sperm deposited directly into oviduct or
  into seminal receptacle
 Sperm can be stored for long periods

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