ZOO 115 Invertebrate Zoology

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ZOO 115 Invertebrate Zoology

• Subphylum Crustacea
• Part II

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Class Maxillopoda

• Small crustaceans with a small trunk
• Subclasses

• Thecostraca

• Copepoda

• Ostracoda

• Branchiura

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Subclass Thecostraca (Barnacles)

• Most sessile
• Acorn

• Stalked (Gooseneck)

• Some Parasitic

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Subclass Theostraca - Anatomy

• Sessile forms
• Shell (calcareous plates) for preventing
  dessiciation and protection
• Hermaphrodites
• Penis 15X body length

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Subclass Thecostraca

• Development
• Nauplius larvae

• Cypris larvae

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Subclass Thecostraca

• Economic importance

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Subclass Copepoda

• Number of species
• 12,000 species
• 2nd largest class in Arthropoda (Malocostraca
  1st) with respect to number of species
• Possibly numerically the most abundant metazoans
  on earth.
• Size
• Most small 1-5 mm
• Some freeliving up to 17 mm
• Parasitic up to 32 cm

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Subclass Copepoda General Anatomy

• Single median eye

• Distinctive narrowing of body at abdomen

• No abdominal appendages

• Well developed caudal rami

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Subclass Copepoda Calanoid

• Live primarily in plankton
• both marine and freshwater
• 1st pair of uniramous Antennae for propulsion
  and flotation
• In males used to hold female for copulation
• 2nd pair of biramous antennae for propulsion
• Large oil sac in thorax for flotation and food
  reserves (often red or blue)

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Subclass Copepoda Calanoid

• Suspension feeders
• 2nd pair of maxilla used for suspension feeding

• Few are predators
• Few are omnivores

Eats juvenile fishes
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Subclass Copepoda - Harpacticoid

• Most epibenthic
• most detrivores
• some predators
• some planktonic forms
• Also use large oil sac for flotation and food
  reserves (often red or blue)
• Some predators

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Subclass Copepoda - Cyclopoid

• Most planktonic
• most predators
• some suspension feeders

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Subclass Copepod - Parasites

• Ectoparasites

• Endoparasites

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Subclass Copepoda

• Fertilization is internal
• indirect with spermatophore
• Males usually smaller than females
• Some brood eggs
• Some release eggs into sea

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Subclass Copepoda

• Nauplius larva
• Copepodid larva
• Freshwater forms can create cysts to protect them
  in winter.

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Subclass Ostracoda (seed shrimps)

• Found in freshwater and marine
• swim or crawl
• Most lt 1mm
• Gigantocypris 25mm
• Enclosed in a bivalve shell but not hinged

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Subclass Ostracoda (seed shrimps)

• 1st antennae used for sensory but sometimes
  digging
• Swim (and sometimes walk) with 2nd antennae

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Subclass Ostracoda (seed shrimps)

• Nutrition
• Most suspension feeders
• some predators or scavengers
• Gigantocypris sp is known to feed on fish
• some deposit feeders

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Subclass Ostracoda (seed shrimps)

• Large fossil record
• most extensive of any crustaceans
• continuous from Cambrian period

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Subclass Ostracoda (seed shrimps) - Reproduction

• Most use bioluminescence to attact mates
• Fertilization is internal and direct
• some freshwater species are parthenogenic (like
  the Cladoceran Daphnia)
• Nauplius larvae

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Subclass Branchiura (fish lice)

• Ectoparasites
• marine and freshwater fish
• In Argulus sp, large preoral spine connected to
  poison glands
• Can swim
• Copulation occurs on host but eggs deposited
  elsewhere