SP. Crustacea

1
SP. Crustacea

• Circulatory system
• all arthropods have open circulatory system
• no veins separate blood from interstitial fluid
• annelids/vertebrates have closed system
• hemolymph leaves ? by arteries
• washes through hemocoel
• returns to ? via surrounding sinuses
• valves in arteries prevent backflow of hemolymph
• dorsal ? is propulsive organ
• single-chambered sac of striated muscle
• hemolymph colorless/reddish/bluish
• ameboid cells secrete thrombinlike coagulant to
  prevent clotting
• hemocyanin/hemoglobin are R pigments

2
SP. Crustacea

• Nervous/sensory systems
• more fusion of ganglia than other arthropods
• more-developed sense organs than annelids
• supraesophageal ganglia supply nerves to
  eyes/antennae
• subesophageal ganglia supply nerves to
  mouth/appendgages/ esophagus
• double ventral nerve cord w/ pair of ganglia for
  each somite controls appendages
• tactile hairs on chelae/mouthparts/telson
• taste/smell via hairs on antennae/mouth
• statocyst lined w/ sensory hairs
• detect position of grains of sand (statholith)
• cmpd eyes made of ommatidia
• transparent area of cuticle (cornea)
• distal retinal/proximal retinal/reflecting
  pigment cells form sleeve around each ommatidium
• each ommatidium behaves as tiny eye
• restricted area of vision in bright light

3
SP. Crustacea

• Reproduction and life cycle
• dioecious mostly
• most brood eggs in brood chambers/
  brood sacs attached to
  abdomen/
  carry eggs w/ abdominal appendages
• most crustaceans undergo metamorphosis
• nauplius is common larval form
• 3 pair appendages
• uniramous 1st antennae
• biramous 2nd antennae
• appendages/somites added
  in series
  of molts
• ? are scarce in some ostracods
• reproduction via parthenogenesis

4
SP. Crustacea

• Molting/ecdysis
• necessary to ? size
• affects reproduction/behavior/metabolic processes
• underlying epidermis secretes cuticle
• outermost epicuticle very thin lipid-impregnated
  protein
• most cuticle consists of 1 layers procuticle
• exocuticle beneath epicuticle
  contains
  protein/calcium salts/chitin
• endocuticle
• heavily calcified principal layer
• uncalcified membranous layer

5
SP. Crustacea

• epidermal cells enlarge before ecdysis
• secrete new epicuticle/exocuticle
• enzymes dissolve old endocuticle
• when only old exocuticle/epicuticle remain,
  animal
  swallows water to burst old cuticle
• old exocuticle/epicuticle shed
• endocuticle secreted
• soft new cuticle stretches/hardens w/
  deposition of
  inorganic salts

6
SP. Crustacea

• Hormonal control of ecdysis
• temperature/day length/other stimuli trigger CNS
  to begin ecdysis
• CNS ? production of molt-inhibiting hormone by
  X-organ
• promotes release of molting hormone from Y-organs
  
• triggers ecdysis
• Other endocrine func.
• removing eyestalks accelerates
  molting (b/c remove
  X-organ)
• prevents camouflage color changes
• hormones from neurosecretory
  cells in
  eyestalk control pigment
  dispersal

7
SP. Crustacea

• Feeding habits
• same fundamental mouthparts adapted to wide array
  of feeding habits
• suspension feeders generate water currents to eat
  plankton/detritus/bacteria
• predators consume larvae/worms/crustaceans/snails/
  fishes
• scavengers eat dead animal/plant matter

8
SEE TABLE on p. 402
9
SP. Crustacea C. Remipedia

• 10 described sp.
• Live in caves connected to sea
• 25-38 segments w/ similar/paired/
  biramous/swimming appendages
• Biramous antennules
• Prehensile maxillae/maxillipeds
  specialized for feeding
• Swimming legs directed laterally
• ventrally in copepods/cephalocarids
• Most primitive crustacean?

10
SP. Crustacea C. Cephalocarida

• 9 described sp.
• Live in coastal bottom sediments
• intertidal to 300 m
• Thoracic limbs/2nd maxillae very similar
• Lack eyes/carapace/abdominal appendages
• True hermaphrodites
• discharge eggs/sperm via same duct

11
SP. Crustacea C. Branchiopoda

• 10,000 sp. in 4 O.
• O. Anostraca includes fairy shrimp/brine shrimp
• lack a carapace
• O. Notostraca includes tadpole shrimp
• carapace forms large dorsal shield
• O. Conchostraca includes clam shrimp
• bivalved carapace
• O. Cladocera includes water fleas
• carapace encloses body not head

12
SP. Crustacea C. Branchiopoda

• All have flattened/leaf-like legs
• 1 R organs
• suspension feeding/locomotion
• Most freshwater zooplankton
• Parthenogenic
• rapidly boost summer populations
• then sexual reproduction w/ onset of unfavorable
  cond.
• Fertilized eggs resistant to cold
• critical for winter survival
• Direct development/gradual metamorphosis

13
SP. Crustacea C. Ostracoda

• 6,000 known sp.
• Most dioecious
• Bivalve carapace
• resemble tiny clams
• 0.25 - 8.0 mm
• Marine/freshwater
• Considerable fusion of trunk somites
• thoracic appendages reduced to 1-2
• gradual metamorphosis

14
SP. Crustacea C. Maxillopoda

• General body plan
• 5 cephalic, 6 thoracic, 4 abdominal somites
  telson
• no appendages on abdomen
• SubC. Mystacocarida
• lt0.5 mm
• live in interstitial water btwn sand grains
• 10 described sp.

15
SP. Crustacea C. Maxillopoda

• SubC. Copepoda
• 3rd in sp.
• lack carapace
• retain nauplius eye in adult
• 1 pair of uniramous maxillipeds
• 4 pairs of flattened/biramous/thoracic
  swimming appendages
• major joint separates posterior from anterior
• appendages on anterior
• antennules often longer than other appendages
• parasites of both vertebrates and invertebrates
• Calanus is most abundant organism in marine
  zooplankton by biomass
• Cyclops/Diaptomus impt freshwater plankton
• intermediate hosts of human parasitic
  tapeworms/nematodes

16
SP. Crustacea C. Maxillopoda

• SubC. Tantulocarida
• 12 describe sp.
• tiny copepod-like ectoparasites of deep-sea
  benthic crustaceans
• larvae penetrate cuticle of the host by a mouth
  tube.
• no head appendages beyond 1 pair of antennae in
  sexual ?
• likely alternate btwn parthenogenetic
  cycle/bisexual cycle w/ fertilization
• abdomen/all thoracic limbs lost during
  metamorphosis to adult

17
SP. Crustacea C. Maxillopoda

• SubC. Branchiura
• lack gills
• parasites of marine/freshwater fish
• 5-10 mm
• broad carapace
• compound eyes
• 4 biramous thoracic swimming appendages
• short unsegmented abdomen
• 2nd maxillae modified as suction cups
• hold on to host fish
• direct development w/o nauplius stage

18
SP. Crustacea C. Maxillopoda

• SubC. Cirripedia (barnacles)
• barnacle adults sessile
• attach directly or by stalk
• acorn vs. goose barnacles
• carapace surrounds body
• secretes set of calcareous plates
• head reduced, abdomen absent
• long thoracic legs w/ hairlike setae
• many-jointed cirri bear setae
• feed on small particles
• intertidal barnacles exposed to drying
• plates close to protect them

19
SP. Crustacea C. Maxillopoda

• monoecious/hermaphroditic
• metamorphosis
• hatch as free-swimming nauplii
• become cyprid larvae w/ bivalve carapace
  compound eyes
• attach to substrate by 1st antennae/adhesive
  glands
• secrete calcareous plates/lose eyes/change
  swimming appendages to filtering cirri

20
SP. Crustacea C. Malacostraca

• 20,000 sp
• most diverse
• largest C. of Crustacea (14 O.)
• O. Isopoda
• terrestrial (sow bugs/pill bugs)
• also marine/freshwater
• dorsoventrally flattened
• lack carapace, sessile compound eyes
• 1st pair of thoracic limbs are maxillipeds
• remaining thoracic limbs lack exopods
• abdominal appendages bear gills
• must live in moist conditions b/c
  
  cuticle lacks protection of insect cuticle
• some parasites of fish/crustaceans
• usually direct development

21
SP. Crustacea C. Malacostraca

• O. Amphipoda
• resemble isopods
• lack carapace, sessile compound eyes
• 1 pair of maxillipeds.
• compressed laterally
• gills in thoracic position
• abdominal/thoracic limbs grouped
  for
  jumping/swimming
• marine/freshwater/parasitic
• direct development

22
SP. Crustacea C. Malacostraca

• O. Euphausiacea (krill)
• 90 sp.
• carapace does not completely enclose gills
• lack maxillipeds and have all limbs equipped
  w/ exopods
• most are bioluminescent via photophore
• major component baleen
  whale/fish diet

23
SP. Crustacea C. Malacostraca

• O. Decapoda (crayfishes/lobsters/crabs/true
  shrimp)
• 18,000 sp.
• 5 pairs of walking legs
• 3 pairs of maxillipeds
• 1st pair of walking legs form pincers
• few mm ? largest arthropod (Japanese crab)
• crabs have broad cephalothorax/reduced abdomen