Zoology Exam 5 – Roelke Questions
and Answers
Describe hormonal control in crustaceans - Answer--Usually initiated by
environmental stimuli
-Stops production of molt inhibiting hormone from the X-organ (neurosecretory cells)
-Promotes release of molting hormone from the Y-organs, which lie near mandibles,
initiate molting
-Androgenic glands occur in some males that don't develop in females, lead to
development of secondary sexual characteristics
Explain crustacean feeding - Answer--Vary greatly, much specialization, but all use
same fundamental set of mouthparts
-Predators eat mostly larvae, worms, other crustaceans, snails, fishes
-Scavengers eat detritus and dead animals
-Suspension feeders eat plankton and bacteria
-Crayfish have a two part stomach with a gastric mill, which shreds food even more
than the mandibles
Describe the mantis and pistol shrimp differences - Answer--Mantis shrimp:
specialized digit for piercing or smashing prey
--piercers and then smashers, either jab stuff or bash it open
--group called stematopods*
--creates a bubble of air that is considered to be "plasma" when it strikes
-Pistol shrimp: chelae can be cocked like a hammer, second fastest animal motion
recorded
Explain class Remipedia - Answer--Only about ten species, all from caves that enter
the ocean
-25 to 38 trunk segments, all identical, paired, biramous swimming appendages
-Antennules biramous, maxillae and maxillipeds prehensile and adapted for feeding
Explain class Cephalocarida - Answer--Only nine species, 2 to 3 mm long
-Live in sediment
-Thoracic limbs all similar, second maxillae similar to thoracic limbs
-No eyes, carapace, or abdominal appendages
-True hermaphrodites, eggs and sperm through a common duct
Explain class Branchiopoda - Answer--10,000 species
-Three orders
--Anostraca: fairy shrimp (sea monkey)
--Notostraca: tadpole shrimp
--Diplostraca: water fleas
-Have flattened, leaflike phyllopodia, or legs that serve as respiratory organs
-Mostly freshwater
--Many with complex life cycles with extensive periods of dormancy
,-Very important components of food webs
Explain class Maxillopoda - Answer--10,000 species
-Five cephalic, six thoracic, four abdominal segments, but reductions are common
-Nauplii have a unique organ called a maxillopodon eye (PLANKTON FROM
SPONGEBOB)
-Subclass Mystacocarida: tiny, only ten species
-Subclass Copepoda: the copepods, very diverse
-Subclass Tantulocarida: only 12, recently described
-Subclass Branchiura: mostly fish ectoparasites
-Subclass Pentastomida: formerly a phylum, wormlike
-Subclass Cirripedia: the barnacles, which are awesome
Describe subclass Mystacocarida - Answer--Less than 0.5 mm long
-Distributed worldwide, but only ten species
-Live in interstitial spaces in sand
Describe subclass Copepoda - Answer--Very abundant, usually less than 2 mm in
length
-Lack carapace, retain their nauplius eye into adulthood
-Single pair of uniramous maxillipeds and four pairs of flattened, biramous, thoracic
swimming appendages, fifth pair of legs reduced
-Most free living but many parasitic
-Development usually direct, some parasitic species exhibit specialized multiphasic
life cycles
-***Plankton from spongebob is in this subclass
Describe the subclass Tantulocarida - Answer--Only described in 1983, about 12
species
-Tiny, smaller than 0.2 mm
One pair of antennae on sexual females
-Have both a parthogenetic life cycle and a sexual life cycle
-Parasitic, tantulus larvae penetrate the cuticle of hosts by a mouth tube. Then their
abdomen and all thoracic limbs lost during metamorphosis to an adult.
-Juveniles bear six or seven abdominal segments
Describe the subclass Branchiura - Answer--Small group of mostly fish ectoparasites
with sucking mouthparts
-Broad, shieldlike carapace, compound eyes, four biramous thoracic appendages
and a short, unsegmented abdomen
-Second maxillae modified as suction cups
-No nauplius, young resemble adults
Describe the subclass Pentastomida - Answer--130 species of wormlike parasites,
called the tongueworms
-Mostly lung parasites of vertebrates, up to 13 cm
-Transverse rings make them look segmented
-Nonchitinous, highly porous cuticle, molted periodically during larval stages
-Sometimes have five short protuberances on anterior end
-Simple, straight digestive system
, -No circulatory, excretory, or respiratory organs
-Sexes separate, females usually larger than males
-Larvae are ovoid, tailed, with four stumpy legs
-Have very complex life cycles with intermediate hosts
Describe the subclass Cirripedia - Answer--Barnacles, plus three smaller orders of
burrowing or parasitic forms
-Sessile as adults
-Carapace surrounds body and secretes shell of calcareous plates
-Head reduced, no abdomen, thoracic legs long, many jointed cirri with hairlike setae
-Cirri extended between plates for filter feeding
-Most hermaphroditic, have internal fertilization, become free living cyprid larvae,
attach by their first antennae, metamorphose into adult form
-Longest penis in relation to body size of any animal!
-***an example of phylogenetic constraint in evolution
Explain the class Malacostraca - Answer--20,000 species, largest class, great
diversity
--Order Isopoda: the rolly polys and their friends
--Order Amphipoda: like isopods but compressed laterally
--Order Euphausiacea: the krill
--Order Decapoda: the tasty guys, lobsters, crabs, shrimp
-Very important economically for food, scavenging, and forming the base of many
food webs
Describe order Isopoda - Answer--Have invaded terrestrial habitats all the way to
very deep water
-Dorsoventrally flattened, no carapace, have sessile compound eyes
-Maxillipeds are the first pair of thoracic limbs, others lack exopods
-Development usually direct, a few parasitic forms have complex life cycles
Describe the order Amphipoda - Answer--Resemble isopods, but compressed
laterally
-Gills in typical Malacostracan thoracic position
-Thoracic and abdominal limbs differ in function (eg: one pair for swimming and one
pair for jumping)
-Development direct, no metamorphosis
Describe the order Euphausiacea - Answer--About 90 species, known as the krill
-3 to 6 cm long
-Carapace fused with all thoracic segments, does not entirely enclose their gills
-No maxillipeds, but have thoracic limbs with expopods
-Many bioluminescent because of an organ called a photophore
-Very important to marine food webs
Describe the order Decapoda - Answer--About 18,000 species
-Three pairs of maxillipeds and five pairs of walking legs
-Some walking legs modified to form chelae (claws)
-Largest arthropod is a Japanese spider crab (4 m)
-***decorator crab, north atlantic lobster, cleaner shrimp, Pinchy the lobster
and Answers
Describe hormonal control in crustaceans - Answer--Usually initiated by
environmental stimuli
-Stops production of molt inhibiting hormone from the X-organ (neurosecretory cells)
-Promotes release of molting hormone from the Y-organs, which lie near mandibles,
initiate molting
-Androgenic glands occur in some males that don't develop in females, lead to
development of secondary sexual characteristics
Explain crustacean feeding - Answer--Vary greatly, much specialization, but all use
same fundamental set of mouthparts
-Predators eat mostly larvae, worms, other crustaceans, snails, fishes
-Scavengers eat detritus and dead animals
-Suspension feeders eat plankton and bacteria
-Crayfish have a two part stomach with a gastric mill, which shreds food even more
than the mandibles
Describe the mantis and pistol shrimp differences - Answer--Mantis shrimp:
specialized digit for piercing or smashing prey
--piercers and then smashers, either jab stuff or bash it open
--group called stematopods*
--creates a bubble of air that is considered to be "plasma" when it strikes
-Pistol shrimp: chelae can be cocked like a hammer, second fastest animal motion
recorded
Explain class Remipedia - Answer--Only about ten species, all from caves that enter
the ocean
-25 to 38 trunk segments, all identical, paired, biramous swimming appendages
-Antennules biramous, maxillae and maxillipeds prehensile and adapted for feeding
Explain class Cephalocarida - Answer--Only nine species, 2 to 3 mm long
-Live in sediment
-Thoracic limbs all similar, second maxillae similar to thoracic limbs
-No eyes, carapace, or abdominal appendages
-True hermaphrodites, eggs and sperm through a common duct
Explain class Branchiopoda - Answer--10,000 species
-Three orders
--Anostraca: fairy shrimp (sea monkey)
--Notostraca: tadpole shrimp
--Diplostraca: water fleas
-Have flattened, leaflike phyllopodia, or legs that serve as respiratory organs
-Mostly freshwater
--Many with complex life cycles with extensive periods of dormancy
,-Very important components of food webs
Explain class Maxillopoda - Answer--10,000 species
-Five cephalic, six thoracic, four abdominal segments, but reductions are common
-Nauplii have a unique organ called a maxillopodon eye (PLANKTON FROM
SPONGEBOB)
-Subclass Mystacocarida: tiny, only ten species
-Subclass Copepoda: the copepods, very diverse
-Subclass Tantulocarida: only 12, recently described
-Subclass Branchiura: mostly fish ectoparasites
-Subclass Pentastomida: formerly a phylum, wormlike
-Subclass Cirripedia: the barnacles, which are awesome
Describe subclass Mystacocarida - Answer--Less than 0.5 mm long
-Distributed worldwide, but only ten species
-Live in interstitial spaces in sand
Describe subclass Copepoda - Answer--Very abundant, usually less than 2 mm in
length
-Lack carapace, retain their nauplius eye into adulthood
-Single pair of uniramous maxillipeds and four pairs of flattened, biramous, thoracic
swimming appendages, fifth pair of legs reduced
-Most free living but many parasitic
-Development usually direct, some parasitic species exhibit specialized multiphasic
life cycles
-***Plankton from spongebob is in this subclass
Describe the subclass Tantulocarida - Answer--Only described in 1983, about 12
species
-Tiny, smaller than 0.2 mm
One pair of antennae on sexual females
-Have both a parthogenetic life cycle and a sexual life cycle
-Parasitic, tantulus larvae penetrate the cuticle of hosts by a mouth tube. Then their
abdomen and all thoracic limbs lost during metamorphosis to an adult.
-Juveniles bear six or seven abdominal segments
Describe the subclass Branchiura - Answer--Small group of mostly fish ectoparasites
with sucking mouthparts
-Broad, shieldlike carapace, compound eyes, four biramous thoracic appendages
and a short, unsegmented abdomen
-Second maxillae modified as suction cups
-No nauplius, young resemble adults
Describe the subclass Pentastomida - Answer--130 species of wormlike parasites,
called the tongueworms
-Mostly lung parasites of vertebrates, up to 13 cm
-Transverse rings make them look segmented
-Nonchitinous, highly porous cuticle, molted periodically during larval stages
-Sometimes have five short protuberances on anterior end
-Simple, straight digestive system
, -No circulatory, excretory, or respiratory organs
-Sexes separate, females usually larger than males
-Larvae are ovoid, tailed, with four stumpy legs
-Have very complex life cycles with intermediate hosts
Describe the subclass Cirripedia - Answer--Barnacles, plus three smaller orders of
burrowing or parasitic forms
-Sessile as adults
-Carapace surrounds body and secretes shell of calcareous plates
-Head reduced, no abdomen, thoracic legs long, many jointed cirri with hairlike setae
-Cirri extended between plates for filter feeding
-Most hermaphroditic, have internal fertilization, become free living cyprid larvae,
attach by their first antennae, metamorphose into adult form
-Longest penis in relation to body size of any animal!
-***an example of phylogenetic constraint in evolution
Explain the class Malacostraca - Answer--20,000 species, largest class, great
diversity
--Order Isopoda: the rolly polys and their friends
--Order Amphipoda: like isopods but compressed laterally
--Order Euphausiacea: the krill
--Order Decapoda: the tasty guys, lobsters, crabs, shrimp
-Very important economically for food, scavenging, and forming the base of many
food webs
Describe order Isopoda - Answer--Have invaded terrestrial habitats all the way to
very deep water
-Dorsoventrally flattened, no carapace, have sessile compound eyes
-Maxillipeds are the first pair of thoracic limbs, others lack exopods
-Development usually direct, a few parasitic forms have complex life cycles
Describe the order Amphipoda - Answer--Resemble isopods, but compressed
laterally
-Gills in typical Malacostracan thoracic position
-Thoracic and abdominal limbs differ in function (eg: one pair for swimming and one
pair for jumping)
-Development direct, no metamorphosis
Describe the order Euphausiacea - Answer--About 90 species, known as the krill
-3 to 6 cm long
-Carapace fused with all thoracic segments, does not entirely enclose their gills
-No maxillipeds, but have thoracic limbs with expopods
-Many bioluminescent because of an organ called a photophore
-Very important to marine food webs
Describe the order Decapoda - Answer--About 18,000 species
-Three pairs of maxillipeds and five pairs of walking legs
-Some walking legs modified to form chelae (claws)
-Largest arthropod is a Japanese spider crab (4 m)
-***decorator crab, north atlantic lobster, cleaner shrimp, Pinchy the lobster
