lecture midterm 3

Question 1

restrictions for spot prawn fishing

Answer 1

males turn into females (hermaphroditic) at a certain age and size –> so can fish for these once theyre big enough and after breeding season bc they only breed once –> fish them when big enough and after they breed

SAMPLE BY SPAWNERS INDEX:
- ratio to females and males in trap
- entire fishery managed by this single indicator
– need to have spawners index model including abundance

dont even truly know life span - here 4 years in cali they say 5 years, alaska they say 5-7

most males transition after 3 years - 4 year life span – transition takes 8 months
some males transition early

how theyre sorted:
- smaller ones fall thru net (self-sorting)
- then picked thru by hand

Question 2

phylum arthropoda 2 subclasses

Answer 2

subclass chelicerata

subclass mandibulata

Question 3

phylum arthropoda - subclass chelicerata

Answer 3

mostly terrestrial - some sea spiders and horseshoe crab
- arachnids

2 tagmata:
- prosoma (forebody) - 6 pairs of appendages
- opisthosoma (hindbody) - varied # of appendages

specialized appendages –>
- first pair = chelicerae (always for feeding)
– chelate appendages - pincher
- second pair = pedipalps (diversity of functions)

CHELICERAE ARE DETERMINING CHARACTERISTIC

Question 4

tagmata in different species
- horse shoe crab (merostomata)
- scorpion (arachnida)

Answer 4

horse shoe crab (phylum merostomata)
- prosoma (top)
- opisthosoma (back)
- telson (tail)

scorpion (phylum arachnida)
- pedipalps
- prostoma
- opisthosoma (2 sections) – telson
– modified appendages

Question 5

distinctive feature of horse shoe crabs

Answer 5

highly modified appendages

book gills

thin folded exoskeleton - gill lamellae
- protected by gill operculum

Question 6

class arachnida

Answer 6

• terrestrial
• opisthosoma have few (if any) appendages
• predators (w exceptions)
• gas exchange structures similar to horse shoe crabs – book lungs or trachaea
• reproduction: males transfer spermatophores (w exceptions)

Question 7

class arachnida - ex spiders

Answer 7

chelicerae NOT chelate - not hard w pinchers

pedipalps getting bigger but not as big to be walking legs

well developed chelicera - storage place for neurotoxins

see narrow pedicel - for silk

pedipalp quite large - for feeding

Question 9

diagnostic feature of scorpions

Answer 9

pectine - mechanosensory - to feel vibrations on ground to catch prey

Question 10

book gills

Answer 10

in horse shoe crab (merostomata)
- outside animal (marine)
- gill lamellae
- gill operculum
- part of opisthosoma

in arachnida (spiders, scorpions)
- inside animal (internalized lungs)
- gill lamellae
- external pore (spiracle)

Question 11

modified appendages in arthropods (merostomata, arachnids, pycnogonida)

Answer 11

merostomata:
- book gills (external) on opisthosoma

arachnids - spiders
- some have spinnerets as modified appendage on opisthosoma

pycnogonida - sea spiders
- opisthosoma reduced to only anus
- modified appendage = proboscis for feeding
- long leg for male to hold eggs (ovigerous leg)